DENTAL BIOCHEMISTRY & PHYSIOLOGY

Which amino acid is taken up by chromaffin cells in the adrenal medulla and converted to hormones? • Alanine • Tyrosine • Proline • Arginine

Tyrosine *** Tyrosine is converted to epinephrine and norepinephrine. Secretion of these hormones is stimulated by acetylcholine release from preganglionic sympathetic fibers innervating the medulla. Common stimuli for secretion of adrenomedullary hormones include exercise, hypoglycemia, hemorrhage, and emotional distress. Following release into blood, these hormones bind adrenergic receptors on target cells, where the hormones induce essentially the same effects as direct sympathetic nervous stimulation. Outside the nervous system, norepinephrine and its methylated derivative epinephrine act as regulators of carbohydrate and lipid metabolism. Norepinephrine and epinephrine increase the degradation of triacylglycerol and glycogen as well as increase the output of the heart (specifically, epinephrine) and blood pressure. These effects are part of a coordinated response to prepare the individual for emergencies and are often called the "fight or flight" reactions. Norepinephrine can be released in 2 ways: • By the adrenal medulla into the bloodstream (as discussed above). • Directly onto an organ by a postganglionic sympathetic (adrenergic) neuron that stores norepinephrine. Important: The effects are more widespread when norepinephrine is released into the bloodstream by the adrenal medulla as opposed to directly onto an organ by a postganglionic sympathetic neuron.

The T wave of an electrocardiogram wave segment represents the of the } --_, • Depolarization / atria • Depolarization / ventricles • Depolarization / atria • Depolarization / ventricles

repolarization / ventricles An electrocardiogram (ECG or EKG) is a test that measures the electrical activity of the heart. The signals that make the heart's muscle fibers contract come from the sinoatrial node, which is the natural pacemaker of the heart. The principal ECG intervals are between the P, QRS, and T waves. Remember: 1. The P wave is the electrical recording from the body surface of atrial depolar¬ization and precedes atrial contraction. 2. The QRS complex represents ventricular depolarization. 3. The first heart sound represents closure of the AV valves at the onset of systole. 4. The second heart sound represents closure of the semilunar valves at the onset of diastole. ***There is no distinctly visible wave representing atrial repolarization in the ECG because atrial repolarization occurs during ventricular depolarization, and is thus obscured. 1. An ECG that shows extra P waves before each QRS complex indicates partial heart block (or second-degree block). 2. An ECG that shows the P wave and the QRS complex being dissociated is indicative of complete heart block; that is, there is no correlation between the P wave and the QRS-T complex on the ECG

Venous return is the blood returning to the heart via the inferior and superior vena cavae. There are four key actions that facilitate the return of blood. Fill in the blanks (using options in parentheses) so that each statement describes a situation that will increase venous return to the h • The contraction of (skeletal / cardiac / smooth) muscle • A (n) (increase / decrease) in intrathoracic pressure • The presence of venous (valves / peristalsis) • A (n) (increase / decrease) in venous compliance

skeletal decrease valves decrease Venous return is influenced by several factors. • Muscle contraction. Rhythmical contraction of limb muscles as occurs during normal locomotory activity (walking, running, swimming) promotes venous return by the muscle pump mechanism. • Decreased venous compliance. Sympathetic activation of veins decreases venous compliance, increases central venous pressure, and promotes venous return indirectly by augmenting cardiac output through the Frank-Starling mechanism, which increases the total blood flow through the circulatory system. • Respiratory activity. During respiratory inspiration, the venous return increases because of a decrease in right atrial pressure. • Vena cava compression. An increase in the resistance of the vena cava. Remember: Under normal circumstances, the rate of venous return is the major factor that determines cardiac output as stated in Starling's law of the heart (or the Frank-Starling mechanism). 1. Contractions in skeletal muscles (especially in the legs) pushe on the blood Notes in the veins, which is directed back toward the heart because of one-way valves in the veins. Thus, rhythmic contractions of the leg muscles will counteract the force of gravity, which tends to cause pooling of blood in the feet in standing persons. 2. Veins have a great degree of compliance that can be regulated by the sympathetic nervous system. An increase in sympathetic activation decreases venous compliance and increases venous return. Important: An increase in intrathoracic pressure will decrease venous return.

Which of the following statements about the urea cycle is correct? • The two nitrogen atoms that are incorporated into urea enter the cycle as ammonia and alanine • Urea is produced directly by the hydrolysis of ornithine • ATP is required for the reaction in which argininosuccinate is cleaved to form arginine • Urinary urea is increased by a diet rich in protein • The urea cycle occurs exclusively in the cytosol

Urinary urea is increased by a diet rich in protein *** The amino nitrogen of dietary protein is excreted as urea. Urea is the major end product of nitrogen metabolism in humans and mammals. Ammonia, the product of oxidative deamination reactions, is toxic in even small amounts and must be removed from the body. The urea cycle or the ornithine cycle describes the conversion reactions of ammonia into urea. Since these reactions occur in the liver, the urea is then transported to the kidneys where it is excreted. The overall urea formation reaction is: 2 Ammonia + carbon dioxide + 3 ATP -- urea + water + 3 ADP 1. The two nitrogens enter the urea cycle as ammonia and aspartate. 2. Urea is produced by the hydrolysis of arginine. 3. The cleavage of argininosuccinate does not require ATP. 4. The urea cycle occurs partly in the mitochondria. 5. A complete block of any step in the urea cycle is fatal since there is no known alternative pathway for the synthesis of urea. 6. Inherited disorders from defective enzymes may cause a partial block in some of the reactions and results in hyperammonemia, which can lead to mental retar¬dation. 7. Extensive ammonia accumulation leads to extensive liver damage and death. 8. Liver cirrhosis caused by alcoholism creates an interference in the enzymes that produce carbamyl phosphate in the first step in the cycle. 9. The level of nonprotein nitrogen in the blood is due primarily to the level of urea. 10. Death from advanced liver disease is primarily due to the inhibition of urea synthesis.

Summary of Vitamin E Dietary Sources Major Body Functions Deficiency

Vegetable oil and seeds, green leafy vegetables, margarines, shortenings Functions as an antioxidant, inhibiting the breakdown of unsaturated fatty acids Is almost entirely restricted to premature infants

Which cardiac muscle has a longer refractory period? • Ventricular muscle • Atrial muscle

Ventricular muscle -- 0.25 to 0.3 seconds *** Atrial muscle has a refractory period around 0.15 seconds. Therefore, the rhythmical rate of contraction of the atria can be much faster than that of the ventricles. This long refractory period (also called absolute refractory period) of cardiac muscle is responsible for preventing the heart from undergoing re¬entry, which would not allow the heart to relax and refill with blood. Important: (1) By preventing premature re-entry, cardiac muscle is prevented from ever undergoing tetanus. (2) The strength of cardiac muscle contraction is increased when extracellular Ca++ is increased. For comparison, the time required for excitation to spread throughout the heart is 0.22 seconds. Important: Skeletal muscle cells have a short refractory period that allows them to be stimulated to contract a second time before they have relaxed from an initial contraction. Two types of refractory periods: 1. Absolute: is the period during which another action potential cannot be elicited, no matter how large the stimulus. Note: The length of the absolute refractory period of an action potential is determined by the duration of sodium inactivation gate closure. 2. Relative: begins at the end of the absolute refractory period and continues until the membrane potential returns to the resting level. A second action potential can be elicited only if the stimulus is larger than usual.

Which of the following is required for the balancing of hormonal changes in women as well as assisting the immune system and the growth of new cells? • Vitamin A • Vitamin B6 • Vitamin K • Vitamin B12

Vitamin B6 Vitamin B6 is a collective term for pyridoxine, pyridoxal, and pyridoxamine. They are all derivatives of pyridine, differing only in the nature of the functional group attached to the ring. All three compounds can serve as precursors of the biologically active coenzyme, pyridoxal phosphate. Pyridoxal phosphate functions as a coenzyme for a large number of enzymes, particularly those that catalyze transamination reactions involving amino acids. Vitamin B6 is also used in the processing and metabolism of proteins, fats, and carbo-hydrates, while assisting with controlling mood as well as behavior. Vitamin B6 might also be of benefit for children with learning difficulties, as well as assisting in the prevention of dandruff, eczema, and psoriasis. Vitamin B6 assists in the balancing of sodium and potassium as well promotes red blood cell production. Vitamin B6 is further involved in the nucleic acids' RNA as well as DNA. It has been linked to cancer immunity and fights the formation of the toxic chemical homocysteine, which is detrimental to the heart muscle. Deficiencies are rare but have been observed in women taking oral contraceptives and in alcoholics. Dietary sources of vitamin B6 include meats (liver), vegetables, whole-grain cereals, and egg yolks.

Which essential nutrient has the highest RDA for the 25-50 age group? ) • Riboflavin • Vitamin E • Vitamin C • Folacin

Vitamin C 1. Vitamin C is also called ascorbic acid. 2. It is an antioxidant. 3. Vitamin C deficiency primarily affects connective tissue (as opposed to hematopoietic, epithelial, muscular, or nervous tissue) 4. Vitamin C is essential for the normal elaboration and maintenance of bone matrix, cartilage, and dentin.

Which fat-soluble vitamin below is a steroid hormone and is known for its ....._ important role in regulating body levels of calcium and phosphorus? • Vitamin A • Vitamin D • Vitamin E • Vitamin K

Vitamin D Vitamin D is a fat-soluble vitamin. It is found in food, but also can be made in the body after exposure to ultraviolet rays from the sun. Vitamin D exists in several forms, each with a different activity. Some forms are relatively inactive in the body, and have limited ability to function as a vitamin. The liver and kidney help convert vitamin D to its active hormone form. Note: 1, 25-dihydroxychole-calciferol is the active form of vitamin D. The major biologic function of vitamin D is to maintain normal blood levels of cal¬cium and phosphorus. Vitamin D aids in the absorption of calcium, helping to form and maintain strong bones. Vitamin D promotes bone mineralization in concert with a number of other vitamins, minerals, and hormones. Without vitamin D, bones can become thin, brittle, soft, or misshaped. Vitamin D prevents rickets in children and osteomalacia in adults. Note: Vitamin D and parathyroid hormone both increase serum calcium.

CApatient of yours with a PhD in nutrition tries to trip you up by saying that he ',...._ supplements every morning with tocopherol. What is he talking about? • Riboflavin • Vitamin E • Vitamin C • Folacin

Vitamin E 1. Vitamin E is also called tocopherol. Notes 2. It prevents free radicals from oxidizing compounds such as polyunsat¬urated fatty acids. 3. It is the least toxic of the fat-soluble vitamins -- vitamin D is the most toxic of all vitamins. 4. Vitamin E supplementation has been proposed to be of benefit in prevention of heart disease and cancer; however, controlled studies have been unable to show a link between vitamin E supplementation and the prevention of these diseases.

All of the following vitamins have little to no risk of overdose EXCEPT one. Which one is the EXCEPTION? • Niacin • Biotin • Vitamin C • Vitamin K

Vitamin K *** The others are water soluble and thus have little, if any, risk of overdose. The water-soluble vitamins, excluding vitamin C, popularly are termed the B-complex vitamins. There are eight of them, namely; B1 (thiamine), B2 (riboflavin) B5 (pantothenic acid), B6 (pyridoxine), niacin (nicotinic acid), B12 (cobalamin). folacin (folic acid), and biotin (vitamin H). The water-soluble vitamins, inactive ir their so-called free states, must be activated to their coenzyme forms. B-comple), vitamins and vitamin C are water-soluble vitamins that are not stored in the bod) and must be replaced each day, preferably through a high-quality liquid multivitamin The water-soluble vitamins are absorbed in our intestine, pass directly to the blood and are carried to the tissues in which the vitamins will be utilized. Vitamin B1: requires a substance known as "intrinsic factor" for absorption. Water-soluble vitamins usually are excreted in the urine on a daily basis. Thiamin( (B1), riboflavin (B2), pyridoxine (B6), ascorbic acid (C), pantothenic acid (B5), anc biotin appear in urine as free vitamins. The tissue storage capacity of water-soluble vitamins is limited, and as the tissues become saturated, the rate of excretior increases sharply. This keeps us from overdosing, but this is also why we need to take these vitamins daily. Unlike the other water-soluble vitamins, however, vitamin B1: is excreted solely in the feces. Remember: Fat-soluble vitamins include vitamins A, D, E, and K. They are carried in fat and can be stored in the body. It is possible to overdose on fat-soluble vitamins.

Which of the following fat-soluble vitamins is necessary for calcium's role in blood clotting? • Vitamin A • Vitamin K • Vitamin E • Vitamin D

Vitamin K -- also called phylloquinone or antihemorrhagic factor The principal role of vitamin K is in the post-translational modification of various blood clotting factors (II, VII, IX, and X), where vitamin K serves as a coenzyme in the carboxylation of certain glutamic acid residues present in these proteins. 1. Vitamin K is synthesized by intestinal bacteria. Notes 2. Warfarin is a synthetic analog of vitamin K, which acts as a competitive ,, inhibitor of prothrombin formation. 3. Vitamin K decreases coagulation time and is present in low concentra¬tions in milk.

Summary of Pantothenic Acid Dietary Sources Major Body Functions Deficiency

Widely distributed in all foods, eggs, liver, and yeast • Component of coenzyme A, which functions in the entry of pyruvic acid into the Krebs cycle and in the degradation of fatty acids • Also a compound of fatty acid synthase • Fatigue • Sleep disturbance • Impaired coordination • Diarrhea • GI, renal problems

Summary of Vitamin A Dietary Sources Major Body Functions Deficiency

Widely distributed in green and yellow vegetables and fruits Constituent of rhodopsin (visual pigment) Maintenance of epithelial tissues Has a role in mucopolysaccharide synthesis, bone growth, and remodeling Xerophthalmia (keratinization of ocular tissue) Night blindness

Your afternoon patient complains that she has consumed "tons of liquids" today. The patient asks if this will have an effect on her urine concentration. What would you say in response to this question? • Your plasma osmolarity is lower than normal, and you will likely excrete a large amount of concentrated urine • Your plasma osmolarity is lower than normal, and you will likely excrete a large amount of dilute urine • Your plasma osmolarity is higher than normal, and you will likely excrete a large amount of concentrated urine • Your plasma osmolarity is higher than normal, and you will likely excrete a large amount of dilute urine What are the normal values for daily glomerular filtrate amount and excretion amount, respectively? • 150 - 250 L; 1 - 2 L • 150 - 250 L; 12 L • 45 - 75 L; 1 - 2 L • 45 - 75 L; 12 L

Your plasma osmolarity is higher than normal, and you will likely excrete a large amount of dilute urine Daily GFR in normal individuals is variable, with a range of 150 to 250 L/24 hr and 1 - 2 L of urine produced per day When tubular secretion and reabsorption processes are completed, the fluid remaining within the tubules is transported to other components of the urinary system to be excreted as urine. Urine consists of water and other materials that were filtered or secreted into the tubules but not reabsorbed. Although the daily GFR in normal individuals is variable, with a range of 150 to 250 L/24 hr., the kidneys normally excrete only 1 to 2 L of urine per day. Approximately 99% of the filtrate is returned to the vascular system, while 1% is excreted as urine. Water and substances the body needs are returned to the blood, whereas waste products and excess fluid and solutes remain in the tubules and are excreted from the body as urine. Note: In response to elevated plasma osmolarity, a small volume of concentrated urine will be produced. If plasma osmolarity is lower than normal, a large volume of dilute urine will be excreted.

Your dental assistant comes in one day all smiles. At lunch, she announces that she is pregnant. You recommend that she makes sure to keep her intake of this mineral high because it helps her immune system, as well as the growth and development of her and her unborn child. She often comes in with loads of perfume on and you are hoping that this change in diet might also improve her sense of smell, so she tones it down a notch. Which mineral are we talking about? • Phosphorus • Cobalt • Copper • Zinc

Zinc Zinc is an essential mineral that is found in almost every cell. Zinc stimulates the activity of approximately 100 enzymes. Zinc supports a healthy immune system, is needed for wound healing, helps maintain your sense of taste and smell, and is needed for DNA synthesis. Zinc also supports normal growth and development during pregnancy, child¬hood, and adolescence.

A tumor of the adrenal gland is causing your patient to conserve sodium the renal tubules causing increased blood volume, pressure, and edema. Where is the location of this adenoma? • Zona glomerulosa of the adrenal cortex • Zona fasciculata of the adrenal cortex • Zona reticularis of the adrenal cortex • Adrenal medulla

Zona fasciculata of the adrenal cortex Important point: Cortisol (glucocorticoid) influences carbohydrate, lipid, and protein metabolism. Glucocorticoids promote gluconeogenesis by inducing synthesis of the enzyme phosphoenolpyruvate carboxykinase (PEPCK). 1. The mineralocorticoid aldosterone and the glucocorticoids are collectively Noted called the corticosteroids. 2. Cortisol and aldosterone are produced from progesterone.

Which of the following factors has no direct effect on pulmonary ventilation? • Arterial Po2 • Arterial Pco2 • Arterial [H] • Arterial [HCO3-]

[HC03] *** HCO3- does not directly affect pulmonary ventilation. HCO3- does have influence, but that is through pH and [H] -- there are no HCO3- sensors. Pulmonary ventilation is the total volume of gas per minute, inspired or expired. Sensory information is coordinated in the brain stem. The output of the brain stem controls the respiratory muscles and the breathing cycle. Receptors for CO2, 02, and H': • Central (medullary) chemoreceptors -- located in medulla; stimuli that incr¬ease breathing rate include an increased Pco2. • Peripheral chemoreceptors -- located in the carotid and aortic bodies; stimuli that increase breathing rate include Po2 (if less than 60 mmHg), Pco2, and pH. Factors That Stimulate These Receptors: • Arterial Po2 (partial pressure of oxygen in arterial blood) -- very low Po2 in arterial blood increases pulmonary ventilation. • Arterial Pco2 (partial pressure of carbon dioxide in arterial blood) is the major stimulus for the respiratory centers -- elevated arterial Pco2 increases ventilation. • Arterial pH -- a low arterial pH (increased hydrogen ion concentration) increases ventilation. *** These various factors interact with one another to regulate breathing. Normal Adult Arterial Values: pH --- 7.35 - 7.45 PCO2 35 - 45 torr Po2 --- .79 ton Co2 --- 23 - 30 mmol/L Normal Adult VenousValues: pH --- 7.31 - 7.41 Pco2 --- 41 - 51 torr Po2 --- 30 - 40 torr Co2 --- 23 - 30 mmol/L

Water-soluble Vitamins (Summary) 1)Major functions 2)Deficiency Symptoms VitaminC Thiamin Riboflavin Niacin

1) • Formation of collagen, helps hold them together and keep them healthy • Wound healing • Maintaining blood vessels, bones, teeth • Absorption of iron, calcium, folacin • Production of brain hormones, immune factors • Antioxidant • Helps release energy from foods • Promotes normal appetite • Important in function of the nervous system • Helps release energy from foods Promotes good vision and healthy skin • Energy production from foods • Aids digestion • Promotes normal appetite • Promotes healthy skin and nerves 2) Bleeding gums Failed wound healing Bruise easily Dry, rough skin Scurvy Sore joints and bones Increased infections Beriberi Edema, heart failure Wernicke's encephalopathy Peripheral neuropathy Oroaculogenital areas are reddened, greasy, scaly, and pruritic Seborrheic dermatitis Angular stomatitis Cheilosis Magenta tongue Pellagra Diarrhea Photosensitive dermatitis Mucosal inflammation Dementia Beefy red tongue

Water-soluble Vitamins (Summary) 1)Major Function 2)Deficiency Symptoms Folate B,2 Pantothenicacid Biotin B6

1)Aids in protein metabolism Promotes red blood cell formation Prevents birth defects of the spine and brain Lowers homocysteine levels and thus coro¬nary heart disease risk Aids in building of genetic material Aids in development of normal red blood cells Maintenance of nervous system Involved in energy production Aids in formation of hormones Helps release energy from carbohydrates Aids in fat synthesis Aids in protein metabolism, absorption Aids in red blood cell formation Helps body use fat Megaloblastic anemia Glossitis Diarrhea Megaloblastic anemia Glossitis Anorexia Sensory neuropathy Dementia Burning foot syndrome Fatigue Abdominal pain and vomiting Insomnia Scaly dermatitis Alopecia Muscle pain Depression Anemia Seborrheic dermatitis Glossitis Cheilosis Angular stomatitis Peripheral neuropathy

Fat-soluble Vitamins (Summary) 1)Major Function 2)Deficiency Symptoms A D E K

1)Helps form skin and mucous membranes and keep them healthy, thus increasing resistance to infections Essential for night vision Promotes bone and tooth development Beta carotene is an antioxidant and protects against cancer Promotes hardening of bones and teeth Increases the absorption of calcium Protects vitamins A and C and fatty acids Prevents damage to cell membranes Antioxidant Major importance in blood clot formation 2)Night blindness Abnormal dryness of the skin, eyes, or mucous membranes KeratomaIacia Perifollicular hyperkeratosis Anorexia Bone changes Osteomalacia in adults Rickets in children Deformity of bone and pathologic fractures Neurologic syndromes including areflexia (absence of reflexes) and gait disturbances May contribute to hemolytic anemia Hypothrombinemia and hemorrhagic disease

Which hormone is often called the "stress hormone"? • Growth hormone (GH) • Thyroid-stimulating hormone (TSH) • Adrenocorticotropic hormone (ACTH) • Follicle-stimulating hormone (FSH) This hormone stimulates the excretion of: • Cortisol • Adrenalin • Aldosterone • Two of the above

1. Adrenocorticotropic hormone (ACTH) 2. Cortisol ACTH secretion is controlled by the hypothalamus, to which the pituitary gland is attached. When the body is stressed, corticotropin-releasing hormone (CRH) produced by the hypothalamus travels through a portal system to the anterior lobe of the pituitary, where the hormone induces the production and secretion of ACTH by the basophils of the pars distalis. ACTH in turn stimulates the adrenal cortex to synthesize and secrete cortisol. 1. The secretion of aldosterone from the adrenal cortex is induced not by ACTH but by the elevated plasma potassium and by angiotensin. Aldost¬erone's primary effect is on the kidney tubules, where it stimulates sodium retention and potassium excretion. 2. Analysis of ACTH is used as an indicator of pituitary function and is useful in the differential diagnosis of the following: Addison's disease, congenital adrenal hyperplasia, and Cushing's syndrome. 3. ACTH deficiency is characterized by adrenal insufficiency symptoms such as weight loss, lack of appetite (anorexia), weakness, nausea, vomiting, and low blood pressure.

Ammonia is produced from the metabolism of a variety of compounds. 1. Which compound listed below is quantitatively the most important source of ammonia? 2. Which compound is not a source of ammonia? 3. Which compound is converted to ammonia mainly in the kidney? • Glutamine • Amino acids • Amines • Purines and pyrimidines • Triglycerides

1. Amino acids 2. Triglycerides 3. Glutamine Sources of Ammonia: 1. From amino acids: many tissues, but particularly the liver, form ammonia from amino acids by the aminotransferase and glutamate dehydrogenase reactions. 2. From glutamine: the kidneys (specifically, the tubular cells) form ammonia from glutamine by the action of renal glutaminase. Most of this ammonia is excreted into the urine as NH4, which is an important mechanism for maintaining the body's acid-base balance. 3. From amines: amines obtained from the diet and monoamines that serve as hormones or neurotransmitters give rise to ammonia by the action of amine oxidase. 4. From purines and pyrimidines: in the catabolism of purines and pyrimi-dines, amino groups attached to the rings are released as ammonia. Note: The formation of urea (which is a main product of protein nitrogen metabolism) in the liver is qualitatively the most important disposal route for ammonia. Urea travels in the blood from the liver to the kidneys, where urea passes into the glomerular filtrate. Important: Excessive accumulation of uric acid crystals in the blood causes gout. Remember: Arginase directly catalyzes urea formation in a cell.

You have four patients with the following heart defects. For each patient, choose which portion of the cardiac conduction system that is most likely malfunctioning. 1. Craig has a higher than normal heart rate (tachycardia). 2. Gary's ventricles contract nearly simultaneously with the atria. 3. Ashley's right ventricle does not contract on the lateral side. 4. Jimmy's entire left ventricle does not contract. • Sinoatrial node • Atrioventricular node • Internodal pathways • Atrioventricular bundle • Purkinje fibers

1. Craig -- Sinoatrial node --- the pacemaker of the heart 2. Gary -- Atrioventricular node -- the portion responsible for delaying imp-ulses as they pass from the atria to the ventricles 3. Ashley -- Purkinje fibers are not transmitting impulses to the lateral side of the right ventricle 4. Jimmy -- Atrioventricular bundle is divided, and the left bundle is not transmitting impulses (technically, he could have a problem with all Purkinje fibers on the left side of his heart, but the most likely problem would be at the source of the split -- the AV bundle) The cardiac conduction system arises from the fact that cardiac myocytes are electrically coupled to one another via gap junctions. • SA node (pacemaker): located within the posterior wall of the right atrium near the opening of the superior vena cava. Specialized pacemaker cells depolarize at an intrinsic rate that drives the depolarization of the remainder of the heart. • Internodal pathways: rapidly transmit the wave of depolarization to the left atrium and to the AV node. • Atrioventricular node (AV node): located within the lower right interatrial septum. An impulse is delayed in the AV node for about 0.13 seconds to allow the atria to contract before ventricular contraction. Aside from the AV node, the atria and ventricles are electrically isolated. • AV bundle (bundle of His): originates in the AV node, dividing into two bundle branches that extend down the two sides of the interventricular septum. • Purkinje fibers: originate from the right and left bundle branches, extending to the papillary muscles and lateral walls of the ventricles. The wave of depolar¬ization travels extremely fast through the bundle branches and purkinje fibers (total elapsed time of 0.03 seconds).

Use the same answer options for the following questions. 7 C C1 Your patient has a defective mitral valve, allowing backflow. Which o-f. the following cardiac phases will be least affected by this defect? } ( 2. Normally, which phase would have the highest ventricular pressure? ) • Isovolumetric contraction • Filling phase • Isovolumetric relaxation • Ejection phase

1. Filling phase -- because the mitral valve is open through this phase normally 2. Ejection phase -- isovolumetric contraction would have an increasing pressure right up until the ejection where the pressure would be the highest The spontaneous generation of an action potential within the SA node initiates a sequence of events known as the cardiac cycle. Each cardiac cycle lasts approximately 0.8 seconds and spans the interval from the end of one heart contraction to the end of the subsequent heart contraction. There are two phases of the cardiac cycle. In the diastole phase, the heart ventricles are relaxed, and the heart fills with blood. In the systole phase, the ventricles contract and pump blood into the arteries. During the diastole phase, the atria and ventricles are relaxed. Blood flows into the right and left atria. The valves located between the atria and ventricles are open, allowing blood to flow through to the ventricles. Here is a summary of the events that occur during the diastole phase: • Atrioventricular valves are open • The sinoatrial node, which starts cardiac conduction, contracts, causing atrial contraction • The atria empty blood into the ventricles • Semilunar valves close, preventing backflow into the atria During the systole phase, the ventricles contract pumping blood into the arteries. The right ven¬tricle sends blood to the lungs via the pulmonary artery. The left ventricle pumps blood to the aorta. Here is a summary of the events that occur during the systole phase: • The ventricles contract • Atrioventricular valves close and semilunar valves open • Blood flows to either the pulmonary artery or aorta 1. Blood flow to the coronary arteries would be greatest during ventricular relax¬ation in a resting individual. 2. Ventricular volume is greatest following atrial systole. 3. Ventricular pressure is greatest during ventricular ejection. 4. Increased ventricular volume increases end-diastolic fiber length. This is why an increased filling of the ventricle during diastole causes a more forceful heartbeat.

When scaling and root planing, you are using a firm finger rest for minutes at a time. 1. Which of the following are the receptors that are used in sensing this continuous pressure? 2. Which of the following are the receptors used when you are manipulating an instrument in your fingers? • Pacinian corpuscles • Meissner's corpuscles • Ruffini's end organs • Merkel disks • Hair follicle receptors

1. Pacinian corpuscles 2. Ruffini's end organs Receptors can be classified according to the type of stimulus to which they are sensitive: • Mechanoreceptors are sensitive to pressure or stretch. These receptors are highly prone to adaptation from continued stimuli. Examples include the following: - Pacinian corpuscles are the nerve endings found in the hypodermis or deep in the dermis that sense deep cutaneous pressure, vibration, and proprioception. - Meissner's corpuscles are the nerve endings that are found in the dermal papillae and are associated with two-point discrimination. - Ruffini's end organs are the nerve endings in the dermis of the skin that sense continuous touch or pressure. • Thermoreceptors are free nerve endings sensitive to changes in temperature. • Chemoreceptors are stimulated by various chemicals (in food, the air, or blood). Peripheral chemoreceptors (carotid and aortic bodies) and central chemoreceptors (medullary neurons) primarily function to regulate respiratory activity. This is an important mechanism for maintaining arterial blood Pot, Pco2, and pH within appropriate physiological ranges. • Photoreceptors are specialized receptors that are sensitive to light energy. They are located only in the retinas of the eyes (specifically, the rods and cones). Note: Rods are sensitive down to a single photon of light energy. • Nociceptors are free nerve endings sensitive to painful stimuli. Generally, these have a higher activation threshold than other receptors. Remember: Baroreceptors are specially adapted groups of nerve fibers within the walls of the carotid sinus and the aortic arch. Baroreceptors are stretch receptors that respond to changes in blood pressure.

1. Which of the following is the pace-setting enzyme of glycolysis? 2. Which of the following is the first step to use energy rather than produce it? 3. Which of the following is the enzyme that produces two distinct carbon-based molecules? • Hexokinase • Phosphoglucose isomerase • Phosphofructokinase • Aldolase • Triose phosphate isomerase • Glyceraldehyde-3-phosphate dehydrogenase • Phosphoglycerate kinase • Phosphoglyceromutase • Enolase • Pyruvate kinase

1. Phosphofructokinase 2. Hexokinase -- traps glucose into the cell 3. Aldolase Nine reactions, each catalyzed by a specific enzyme, make up the process we call glycolysis. All organisms have glycolysis occurring in their cytoplasm. At steps 1 and, 3 ATP is converted into ADP, inputting energy into the reaction as well as at¬taching a phosphate to the glucose. At steps 6 and, 9 ADP is converted into the higher energy ATP. At step, 5 NAD+ is converted into NADH + H+. The end of the glycolysis process yields two pyruvic acid molecules, and a net gain of 2 ATP and two NADH per glucose.

Use the following answer options to answer all of the following questions. • QRS complex • Q-T interval • S-T segment • T wave • P-R interval 1. The ventricles are completely depolarized during which isoelectric portion of the ECG? 2. This portion of the ECG represents atrial depolarization. 3. This portion of the ECG represents the segment between depolarization of the atria and depolarization of the ventricle

1. S-T segment 2. P wave 3. P-R interval The Normal Electrocardiogram (ECGI Is R wave Composed of: • P wave: represents atrial depolarization prior to the atria's contraction. • T wave: represents ventricular repolarizat¬ion. • QRS complex: represents ventricular depol¬arization. • S-T segment: represents the period when the ventricles are depolarized; is isoelectric. • P-R interval: represents the length of time between depolarization of the atria and depolarization of the ventricles (approximately 0.16 seconds). Note: varies with heart rate; when HR increases, the P-R interval decreases. • Q-T interval: represents the period between ventricular depolarization and the ventricles' repolarization (approximately 0.35 seconds). Note: The ECG is also isoelectric between the T and P waves (the ventricle is at resting membrane potential). This period of ventricular diastole, when the ventricle is filling with blood, greatly diminishes at high heart rates.

1. Which of the following processes is not involved in the formation of urine? 2. Which two of the following processes in the formation of urine involve the most similar amounts of fluid transport? 3. Which two processes supplement each other, working in the same "direction"? 4. Which process is most affected by levels of ADH? 5. Which process occurs in Bowman's capsule? • Filtration • Reabsorption • Tubular excretion • Secretion

1. Secretion -- urine is secreted once it is formed, secretion is not part of formation 2. Filtration and reabsorption -- about 99% of the filtrate is reabsorbed 3. Filtration and tubular excretion -- both send substances from blood to tubules 4. Reabsorption 5. Filtration The formation of urine had three processes: filtration, reabsorption, and tubular excretion. During filtration, or glomerular excretion, blood pressure forces all the small molecules in the blood into the lumen of the nephron through the pores both in the walls of the glomerular capillaries and in the wall of the Bowman's capsule. The filtrate has the same concentration of dissolved substances as the blood minus the formed elements and the plasma proteins that are too large to fit through the pores of the capillaries and the Bowman's capsule. As the filtrate passes through the tubules of the nephron, water and many dissolved materials are reabsorbed by the blood. In fact, during the filtrate's passage through the tubules, up to 99% of the water is reabsorbed. In addition, the tubules also remove substances from the blood. This process, called tubular excretion, supplements the initial glomerular filtration. Normal urine is clear, straw-colored, and slightly acidic, and has the characteristic odor of urea. The formation of urine is important in the regulation of acid-base balance, maintenance of ECF volume and blood pressure, and in maintaining the normal osmolarity of ECF. Diuresis results from a decrease in the tubular reabsorption of water.

Which of the following represents the pH of a solution that has a 10^-4 M concentration of OH- ion? • 4 • 5 • 8 • 7 • 10

10 This type of problem is solved by using the following equation: Kw = [H+] [OH-] • Kw is the ion product of water and always equals 10-14 • [H1 is the hydrogen ion concentration (pH = -log [11-1) • [OH-] is the hydroxide ion concentration (pOH = -log [OH-]) Therefore, by taking the negative log of both sides, the equation can be rewritten as follows: 14 = pH + p0H Solving the problem on the front of the card --- 14 = pH + 4 pH = 10

Of the 20 amino acids commonly found in proteins, how many are not) .._essential in the adult diet because they can be synthesized in the body? • 5 • 9 • 11 • 18

11 Those amino acids that are synthesized in mammals are generally those with simple pathways. These amino acids are called the nonessential amino acids to denote the fact that they are not needed in the diet. The remainder, the essential amino acids, must be obtained from food. Is can also be classified as ketogenic. glucogenic. or both acc precursors, acetyl-CoA or acetoacetyl-CoA. Examples include leucine and lysine. • Glucogenic: amino acids whose catabolism yields pyruvate or one of the intermediates of the citric acid cycle (a-ketoglutarate, oxaloacetate, fumarate, and succinyl CoA). Examples include the remaining amino acids. • Glucogenic and ketogenic: amino acids whose catabolism yields both ketogenic and glucogenic end products. Examples include tyrosine, isoleucine, phenylalanine, and tryptophan.

Ovulation occurs: • 7 days before menses, regardless of cycle length • 14 days before menses, regardless of cycle length • 18 days before menses, regardless of cycle length • 21 days before menses, regardless of cycle length

14 days before menses, regardless of cycle length The average menstrual cycle usually occurs over 28 days, although the normal cycle may range from 22 to 34 days. The Menstrual Cycle: • Menstrual phase: the cycle starts with menstruation (cycle day 1), which usually lasts 5 days. • Proliferative (follicular) phase: lasts from cycle day 6 to day 14. LH and FSH act on the ovarian follicle (mature ovarian cyst containing the ovum). This leads to estrogen secretion, which in turn stimulates buildup of the endometrium. Note: Late in this phase, estrogen levels peak, FSH secretion declines, and LH secretion increases, surging at mid-cycle (around day 14). Then, estrogen prod-uction decreases, the follicle matures, and ovulation occurs. • Ovulation day: day 15; it occurs as a result of the estrogen-induced LH surge. • Luteal (secretory) phase: lasts about 14 days. FSH and LH levels drop. The corpus luteum begins to develop, and it synthesizes estrogen and progesterone. If fertilization does not occur, the corpus luteum degenerates (become nonviable). As a result, estrogen and progesterone levels decrease until their levels are too low to keep the endometrium in a fully developed secretory state. Note: The endometrial lining is shed as menstrual fluid during menstruation, or menses. *** Decreasing estrogen and progesterone levels stimulate the hypothalamus to prod-uce GnRH, and the cycle begins again.

The oxidation of one NADH by the electron transport chain (or respiratory chain) leads to the formation of: _--) • 1 ATP • 2 ATP • 3 ATP • 4 ATP

3 ATP Pairs of high-energy electrons and their accompanying protons (W) are transferred to the components (cytochromes) of the electron transport chain by NAD and FAD. Then the electrons and protons jump from cytochrome to cytochrome, losing energy along the way. The energy is used to pump protons (11+) into the compartments between the inner and outer mitochondrial membranes. The diffusion of protons back into the inner compartment drives the phosphorylation of ADP to form ATP. The protons are joined together with oxygen and low energy electrons at the end of the cytochrome chain to form water molecules. This all takes place within each mitochondrion. Important: The oxidation of FADH2 yields 2 ATP. 1. Oxidative phosphorylation occurs in the mitochondrial inner membrane, Notes glycolysis occurs in the cytoplasm, and the Krebs cycle (citric acid cycle) occurs in the mitochondrial matrix. Remember: Red blood cells do not contain an active mitochondrial electron transport system. 2. The electron carriers (flavoproteins, iron-sulfur proteins, coenzyme Q, and cytochromes) make up the electron transport system (also called the respiratory chain). During oxidative phosphorylation, the proton gradient, created using energy from the electron transport system, is used to produce ATP. The proton gradient is created by increasing the proton concentration outside the inner membrane of the mitochondria.

In most human cells, one glucose molecule produces enough usable chemical energy to synthesize: • 30-32 ATP molecules • 32-34 ATP molecules • 36-38 ATP molecules • 44-48 ATP molecules How many molecules of this ATP do not go through NADH first? ) • 2 • 4 • 6 • 8

36-38 ATP molecules 4 -- 2 from glycolysis and 2 from the Krebs cycle *** Some cells, such as heart and liver cells, shuttle electrons more efficiently and may be able to synthesize up to 38 ATP molecules. A net profit of 4 ATP is produced by substrate-level phosphorylation during glycolysis (2 ATP) and the Krebs cycle (2 ATP), and 32-34 ATP are produced by oxidative phosphorylation during electron transport. Important: A Na+ gradient across the luminal membrane provides the immediate energy source for the transport of glucose into intestinal epithelial cells.

Vitamin A (retinol) is: • Required for blood clotting • Required for the hydroxylation of proline and lysine residues in the precursor of collagen • A constituent of rhodopsin • Required for synthesis of a cofactor required for reactions in the oxidation of pyruvate to carbon dioxide and water

A constituent of rhodopsin 1. Vitamin A, along with vitamins C and D, is required for the normal production of sound dentin and enamel; however, a deficiency of vitamin A will most likely affect the enamel more than the dentin. Whereas, a deficiency in vitamin C will affect the dentin more, due to the role of vitamin C in collagen synthesis.

Which patient is most likely to have metabolic alkalosis? • A patient who is vomiting • A patient with sudden chronic renal failure • A patient ingesting salicylate, leading to salicylate poisoning • A patient with diarrhea

A patient who is vomiting ***All of the other choices cause metabolic acidosis. All of the buffer pairs in body fluids play an important role in acid-base balance. However, only in the bicarbonate system can the body regulate quickly and precisely the levels of both chemical components in the buffer pair. Carbonic acid levels can be regulated by the respiratory system and bicarbonate ion by the kidneys. A 20:1 ratio of base bicarbonate to carbonic acid (BB:CA) will, according to the Henderson-Hasselbalch equation, maintain acid-base balance and normal blood pH. Therefore, from a clinical standpoint, disturbances in acid-base balance depend on the relative quantities of carbonic acid and base bicarbonate in the extracellular fluid. Two types of disturbances, metabolic and respiratory, can alter the proper ratio of these components. Metabolic disturbances affect the bicarbonate element, and respiratory disturbances affect the carbonic acid element of the buffer pair. Metabolic acidosis is excessive blood acidity characterized by an inappropriately low level of bicarbonate in the blood caused by chronic renal failure, diarrhea and salicylate poisoning. Respiratory acidosis is excessive blood acidity caused by a buildup of carbon dioxide in the blood as a result of poor lung function or slow breathing (decrease in respiratory rate). Note: If you administer a high nitrous-oxygen mixture (for example, 90:10) to a patient, this will cause respiratory depression and result in respiratory acidosis. Metabolic alkalosis is a condition in which the blood is alkaline because of an inappro¬priately high level of bicarbonate. Other causes include hyperaldosteronism and the use of thiazide diuretics. Respiratory alkalosis is a condition in which the blood is alkaline because rapid or deep breathing results in a low blood carbon dioxide level. Note: Respiratory alkalosis is much less common than respiratory acidosis.

Which of the following patients has the least chance of edema formation? • A patient with inflammation • A patient who is standing • A patient with venous constriction • A patient with arteriolar constriction

A patient with arteriolar constriction *** Constriction of arterioles causes decreased capillary hydrostatic pressure and, as a result, decreased net pressure (Starling forces) across the capillary wall. Note: Arteriolar dilation increases the likelihood of edema. Venous constriction and standing cause increased capillary hydrostatic pressure and tend to cause edema. Inflammation causes local edema by dilating arterioles and increasing permeability. Conditions That Will Cause Extracellular Fluid Edema: • Increased capillary pressure due, for example, to blockage of a vein. • Decreased plasma colloid osmotic pressure due to decreased plasma protein concentration. • Increased interstitial fluid colloid osmotic pressure caused by a lymphatic obstruction. • Increased capillary permeability, which may occur in certain allergic responses. Edema occurs when the volume of interstitial fluid exceeds the capacity of the lymphatics to return the fluid to the circulation or the accumulation of fluid in a third space, such as the peritoneum (ascites), pleural cavity (hydrothorax), or pericardial sac (pericardial effusion). Important: The physical cause of edema is positive pressure in the interstitial fluid spaces. Systemic, or generalized edema, may be due to heart failure or renal disease. Massive systemic edema is called anasarca.

A hemoglobin molecule can be distinguished from a myoglobin molecule by the presence of: • A primary structure • A secondary structure • A tertiary structure • A quaternary structure • Both a tertiary and a quaternary structure • None of the above

A quaternary structure *** Remember that myoglobin is monomeric and hemoglobin has four subunits; the quaternary structure is how these four subunits are arranged in space. Proteins differ from each other because each has a distinctive number and sequence of amino acid residues. The amino acids are the alphabet of protein structure. No other property so clearly distinguishes one protein from another. The primary structure consists of a sequence of amino acids linked together by covalent peptide bonds. The secondary structure refers to the spatial arrangement of a portion of a polypeptide chain determined by the amino acids present (primary structure). The most common types of secondary structures are the a-helix (coiled conformation of a peptide chain), (3-pleated sheets (an extended, zigzag arrangement of a polypeptide chain), and (3-hairpin turns (reverse turns). The tertiary structure refers to the irregular folding of a polypeptide chain -- the overall three-dimensional conformation of the polypeptide (e.g., globular, fibrous, and pleated sheet). The quaternary structure refers to the spatial arrangement of subunits in a protein that consists of more than one polypeptide chain. Two examples of proteins with quaternary structures are the hemoglobin and antibody molecules found in the blood of a mammal. Note: The best method for determining the three-dimensional structure of a protein is by x-ray diffraction.

Steps of the Mechanism That Produces an Action Potential I 2 3 4 5 6

A stimulus triggers stimulus-gated Na' channels to open and allow inward Na' diffusion. This causes the membrane to depolarize. As the threshold potential is reached, voltage-gated Na- channels open. As more Na- enters the cell through voltage-gated Na' channels, the membrane depolarizes even further. The magnitude of the action potential peaks (at +30 mV) when voltage-gated Na' channels close. Repolarization begins when voltage-gated IC channels open, allowing outward diffusion of K. After a brief period of hyperpolarization, the resting potential is restored by the sodium-potassium pump and the return of ion channels to their resting state.

Possible Causes of Dilute Urine Possible Causes of Concentrated Urine

Absence of ADH Diabetes insipidus Decreased plasma volume Cellular dehydration Diabetes mellitus Excess ADH

The neurotransmitter of the preganglionic sympathetic neurons is: I • Norepinephrine • Acetylcholine • Dopamine • Serotonin

Acetylcholine *** It stimulates action potentials in the postganglionic neurons. The neurotransmitter released by most postganglionic sympathetic neurons is norepinephrine, which binds to alpha and beta adrenergic receptors in tissue. Exceptions: blood vessels in skeletal muscle and sweat glands, which use acetylcholine at muscarinic cholinergic receptors. Note: Each sympathetic preganglionic neuron branches extensively and synapses with numerous postganglionic neurons. It is this high ratio of postganglionic to preganglionic fibers that results in widespread effects throughout the body. Remember: 1. The sympathetic nerves originate in the spinal cord between the segments T1 and 2. Parasympathetic nervous system: the main nerves of the PNS are the vagus nerves. They originate in the medulla oblongata. Each preganglionic parasympa¬thetic neuron synapses with just a few postganglionic parasympathetic neurons, which are located near or in the effectors (organs, muscles, or glands). Important: Acetylcholine is the neurotransmitter of both the pre- and the postgang¬lionic neurons of the parasympathetic nervous system. ACh binds to nicotinic cholinergic receptors on the postganglionic neurons. But ACh released by the postganglionic neurons stimulates muscarinic cholinergic receptors in the tissue.

The enterogastric reflex, which is initiated when the duodenum fills with (?), inhibits the "pyloric pump," thereby inhibiting gastric motility and emptying. • Bicarbonate • Acid chyme • Enkephalins • Water

Acid chyme As acid chyme enters the duodenum, the decreasing pH inhibits gastrin secretion and causes the release of negative or "stop" signals in the duodenum. These take the form of chemicals called enterogastrones, which include GIP (gastric inhibitory peptide). GIP inhibits stomach secretion and motility and allows time for the digestive process to proceed in the duodenum before it receives more chyme. The enterogastric reflex also reduces motility and forcefully closes the pyloric sphinc¬ter. Eventually, as the chyme is removed, the pH increases, and gastrin and the "go" sig¬nal resumes, and the process of digestion occurs all over again. The process of "go" and "stop" signals continues until stomach emptying is complete. Important point: Enterogastrones are released by the small intestine in response to the acidity of the duodenal chyme and the presence of amino acids and free fatty acids in the chyme.

Strictly speaking, the all-or-none principle refers to the: • Strength of muscle contraction • Resting potential • Action potential • Excitatory postsynaptic potential

Action potential Any stimulus strong enough to initiate a nerve impulse is referred to as a threshold stimulus. A single nerve cell, just like a single muscle fiber, transmits an action poten-tial according to the all-or-none principle. The principle states that if a stimulus is strong enough to generate a nerve action potential, the impulse is conducted along the entire neuron at maximum strength, unless conduction is altered by conditions such as toxic materials in cells or fatigue.

The binding of glucagon to its receptor: • Deactivates adenylate cyclase • Activates protein kinase • Activates adenylate cyclase • Causes the breakdown of cyclic AMP to ATP • Causes the production of ATP from cAMP • Deactivates protein kinase

Activates adenylate cyclase When hormones signal the need for metabolic energy, triglycerides stored in adipose tissue are brought out of storage and transported to those tissues (skeletal muscle, heart, and renal cortex) in which fatty acids can be oxidized for energy production. The hormones glucagon and epinephrine activate adenylate cyclase in the adipocyte plasma membrane, raising the intracellular concentration of cAMP. A cAMP-dependent protein kinase, in turn, phosphorylates and thereby activates hormone-sensitive triacyl¬glycerol lipase, which initializes the hydrolysis of the ester linkages of triglycerides -¬forming free fatty acids and glycerol. The fatty acids that are released bind to serum albumin and travel to the tissues, where the fatty scids dissociate from albumin and diffuse into the cells in which the fatty acids will serve as fuel. Note: Insulin causes activation of a phosphorylase that dephosphorylates the homione sensitive lipase and thereby diminishes lipolysis. The glycerol released by lipase action is phosphorylated by glycerol kinase, and the resulting glycerol-3-phosphate is oxidized to dihydroxyacetone phosphate. This comp-ound is then converted to glyceraldehyde-3-phosphate by the enzyme triose phosphate isomerase. Glyceraldehyde-3-phosphate is then oxidized via glycolysis.

Hormone of the Adrenal Target Hormones Source Glands Action(s)

Aldosterone Cortisol Adrenal androgens Adrenal estrogens Epinephrine Norepinephrine Adrenal cortex (zona glomerulosa) Adrenal cortex (zona fasciculata) Adrenal cortex (zona reticularis) Adrenal cortex (zona reticularis) Adrenal medulla Adrenal medulla Kidney General Sex organs Other effectors Sex organs Sympathetic effectors Sympathetic effectors Stimulates kidney tubules to conserve sodium, which, in turn, triggers the release of ADH and the resulting conservation of water by the kidney Promotes gluconeogenesis, lipolysis and proteolysis, immunosuppression In large amounts, it has an anti-inflammatory effect Exact role uncertain, but may support sexual function Thought to be physiologically insignificant Enhances and prolongs the effects of the sympathetic division of the autonomic nervous system Enhances and prolongs the effects of the sympathetic division of the autonomic nervous system

Your patient has a disorder and is unable to metabolize cholesterol Which of the following hormones will he be unable to synthesize? • Insulin • Thyroxine • Growth hormone • Retinoic acid • Aldosterone • Two of the above

Aldosterone With the exception of retinoic acid, the steroid hormones are all derived from cho¬lesterol. Moreover, with the exception of vitamin D, they all contain the same cy¬clopentanophenanthrene ring and atomic numbering system as cholesterol. These hormones are not water-soluble and bind to intracellular receptors, forming com¬plexes that activate or inactivate genes. Amine hormones are derived from tyrosine, an essential amino acid found in most proteins. Amine hormones include the thyroid hormones (T3 and T4) and the cate- cholamines (epinephrine, norepinephrine, and dopamine). Polypeptide hormones are proteins with a defined, genetically coded structure. They include the anterior pituitary hormones (GH, TSH, FSH, LH, and prolactin), the pos¬terior pituitary hormones (ADH and oxytocin), the pancreatic hormones (insulin and glucagon), and PTH. These hormones have the following characteristics: 1. They are synthesized in precursor form (a pre-prohormone). 2. They are usually transported unbound in the plasma. 3. They are stored in secretory vesicles. 4. They act by binding to a plasma membrane receptor and generating a second messenger. Note: A particular hormone does not necessarily affect all cells, only its target cells. Target cells of a hormone possess receptors to which molecules of a hormone can at¬tach. These receptors can be located either on the plasma membrane or within the cell itself.

Which enzyme is used as an indicator of osteoblastic activity? • Creatine phosphate • Hyaluronidase • Alkaline phosphatase • Acid phosphatase

Alkaline phosphatase *** The other marker of bone formation that is used is osteocalcin. This is a bone matrix protein that is the second most abundant protein in bone after type 1 collagen. Alkaline phosphatase is believed either to increase the local concentration of inorganic phosphate or to activate the collagen fibers in such a way that they cause the deposition of calcium salts. Alkaline phosphatase is involved in bone mineralization and hydrolysis of phosphoric esters and functions optimally at pH 8.6. Phosphatases are any of a group of enzymes that liberate inorganic phosphate from phosphoric esters. Two examples are: 1. Alkaline phosphatase: most of this enzyme in normal serum is derived from bone; however, this enzyme is present throughout the body. Note: High levels of this enzyme are seen in Paget's disease of bone and osteosarcomas, while low levels are seen in cases of hypophosphatasia. 2. Acid phosphatase is a phosphatase with optimum functioning at pH 5.4 and is present in the prostate gland. Note: High levels of acid phosphatase are seen in carcinoma of the prostate gland. 1. Creatine phosphate (also called phosphocreatine) is an organic comp-Notes ound found in muscle tissue and capable of storing and providing energy for muscular contraction. 2. Pyrophosphatase also may play a role in the mineralization of bone.

Which of the following cells has a resting potential? • Cardiac muscle cells • Neurons • Histiocytes • Two of the above • All of the above

All of the above All cells (not just excitable cells) have a resting potential: an electrical charge across the plasma membrane, with the interior of the cell negative with respect to the exterior. The size of the resting potential varies but in excitable cells runs about (-) 70 mV. Note: Excitable cells include neurons and muscle cells. In neurons, the action potential is also called the nerve impulse. Depolarization of a membrane occurs when sodium channels open, allowing sodium to move to an area of lower concentration (and more negative charge) inside the cell -- reversing the polarity to an inside-positive state. Important point: During the upstroke of the action potential, the cell depolarizes, or becomes less negative. The depolarization is caused by inward current, which is, by definition, the movement of positive charge into the cell. In nerve and in most types of muscle, this inward current is carried by sodium (Na+). Note: As sodium (Na) floods the cell during initial depolarization, the membrane potential can reach as high as (+) 55 mV (inside positive). Certain external stimuli reduce the charge across the plasma membrane. • Mechanical stimuli (e.g., stretching, sound waves) activate mechanically gated sodium channels • Certain neurotransmitters (e.g., acetylcholine) open ligand-gated sodium channels In each case, the facilitated diffusion of sodium into the cell reduces the resting potential at that spot on the cell creating an excitatory postsynaptic potential or EPSP. If the potential is reduced to the threshold voltage (about -50 mV in mammalian neurons), an action potential is generated in the cell. Important: If the neuron does not reach this critical threshold level, then no action potential will occur (all or none). So long as suprathreshold stimuli can reach the threshold of the cell, they produce the same action potential that threshold stimuli do.

Ameloblasts are involved in producing the enamel matrix by producing which two organic components? • Amelogenins • Enamelins • Apititins • Prismins

Amelogenins Enamelins Ameloblasts produce an enamel matrix (organic matrix) with protein components called amelogenins and enamelins. This organic matrix makes up about 1% to 2% of enamel, and water makes up about 4%. Enamel is a highly mineralized structure containing approximately 95% inorganic matter. The hydroxyapatite crystals, which are made up of calcium and phosphate, are the largest mineral constituents (90% to 95%) of this inorganic matter. Note: Enamel is semipermeable; it is this property of enamel that allows fluoride ions to be absorbed on the hydroxyapatite crystals, forming fluorapatite via fluoride ion displacement of a hydroxyl group. The tooth becomes more resistant to bacteria-producing acids because fluorapatite has a lower solubility product constant than hydroxyapatite (another way of saying this is hydroxyapatite has a higher solubility than fluorapatite). Remember: Enamel is harder than bone. The main reason for this is that enamel hydroxyapatite crystals are larger and more firmly packed. These tightly packed masses of hydroxyapatite crystals are keyhole-shaped rods called enamel prisms and form the structural foundation of enamel. Actually, these hydroxyapatite crystals in enamel are four times larger than those in bone, dentin, and cementum. 1. Amelogenins are low-molecular-weight proteins found in developing tooth enamel, and they belong to a family of extracellular matrix (ECM) proteins. De¬veloping enamel contains about 30% protein, and 90% of this is composed of amelogenins. Although not completely understood, the function of amelogenins is believed to be in organizing enamel rods during tooth development. 2. Enamelins comprise <1% of proteins found in developing enamel.

Proteins are effective buffers because they contain: • A large number of hydrogen bonds in a-helices • A large number of amino acids • Amino acid residues with different pKa's • Peptide bonds that readily hydrolyze, consuming hydrogen and hydroxyl ions

Amino acid residues with different pKa's *** The side chains of the amino acid residues in proteins contain functional groups with different pKa"s. Therefore, the side chains can donate and accept protons at various pH values and act as buffers over a broad pH spectrum. Note: An increase in pK means a stronger ability to bind hydrogen ions. The pH range of our blood is in the range of 7.35-7.45. Acids and bases are being constantly added to the blood through metabolic processes, and therefore, the body needs a way to moderate the effect of these additions. The body actually uses three methods to moderate the effect. The first is with the removal of bicarbonate (HCO3-) ions in the urine. The second is the removal of the CO2 in the blood by the lungs. The third is a buffer composed of carbonic acid (weak acid) and hydrogen carbonate (conjugate base). Carbonic acid is the most important buffer in extracellular fluid including blood due to carbonic acid's decomposition to water and carbon dioxide, the latter being eliminated very rapidly through the lungs. Note: The carbonic acid system is very important in the oral cavity for the neutralization of acids in foods and those produced by oral bacteria. Important: (1) There are also other buffers in blood, such as proteins and phosphate, but they are less important. (2) Blood pH is determined by a balance between bicarbonate and CO2. (3) Hemoglobin is a major intracellular buffer. Remember: Buffer systems most commonly consist of a weak acid (the proton donor) and a "salt," or conjugate base of that acid (the proton acceptor). These systems minimize pH changes brought about by a change in the acid or base content of the solution. These buffer systems reduce the effect of an abrupt change in H+ ion concentration by releasing H+ ions when the pH rises and accepting H+ ions when the pH drops.

Which two situations below will excite the respiratory neurons and increase respiration? • An increase in hydrogen ion concentration in the arterial blood • A decrease in hydrogen ion concentration in the arterial blood • An increase in the Pco2 of arterial blood • A decrease in the Pco2 of arterial blood • An increase in the albumin levels • A decrease in the albumin levels

An increase in hydrogen ion concentration in the arterial blood (decreased pH) An increase in the Pco2 of arterial blood These two are closely related in the following way. Any time the partial pressure of carbon dioxide increases (Pco2), this also increases the hydrogen ion concentration (decreases the pH) because carbon dioxide combines with water to form carbonic acid. This carbonic acid then dissociates into hydrogen ions and bicarbonate. These hydrogen ions decrease the pH of the arterial blood, thus increasing respiration. Peripheral chemoreceptors (carotid and aortic bodies) and central chemoreceptors (medullary neurons) primarily function to regulate respiratory activity. This is an important mechanism for maintaining arterial blood Poe, Pco2, and pH within appropriate physiological ranges. Chemoreceptor activity, however, does affect cardiovascular function either directly (by interacting with medullary vasomotor centers) or indirectly (via altered pulmonary stretch receptor activity). Central chemoreceptors are the maj or regulators of ventilation. The carotid bodies are located on the external carotid arteries near their bifurcation with the internal carotids. Each carotid body is a few millimeters in size and has the distinction of having the highest blood flow per tissue weight of any organ in the body. Important: The hypoxia of high altitude stimulates ventilation. The carotid body senses hypoxia and signals the medulla to stimulate ventilation (hypoxic ventilatory response). Decreased alveolar carbon dioxide allows for an equivalent increase in alveolar oxygen. The cardiovascular system responds to increased catecholamines with a moderate increase in heart rate, blood pressure, and cardiac output. Over days to weeks, there are increases in hematocrit and capillary density, and changes in the tissues and cells.

Which class of antibody constitutes about 75% of the antibodies of the normal person? • IgA • IgD • IgE • IgG • IgM

Antibodies are protein molecules produced by plasma cells in the spleen and lymph nodes in response to stimulation by antigens. Antibodies leave the immune system environment and travel through the circulation to the infection site. Here they interact with microorganisms or other biochemicals and exert a specific immune response. Antibody molecules are composed solely of protein; a typical antibody molecule consists of two "heavy" chains of 400 amino acids and two "light" chains of 200 amino acids.

On his 21st birthday, John celebrates with his first few beers. He notices (along with other symptoms of inebriation) that he has an increased need to urinate. This is physiologically caused by a decrease in production of: • Oxytocin • Antidiuretic hormone (ADH) • Parathyroid hormone (PTH) • Aldosterone

Antidiuretic hormone (ADH) Antidiuretic hormone, also known commonly as vasopressin, is a nine-amino acid peptide secreted from the posterior pituitary. Within hypothalamic neurons (supraoptic nuclei), the hormone is packaged in secretory vesicles with a carrier protein called neurophysin, and both are released upon hormone secretion. The single most important effect of antidiuretic hormone is to conserve body water by re-ducing the loss of water in urine. Antidiuretic hormone binds to receptors on cells in the col-lecting ducts of the kidney and promotes reabsorption of water back into the circulation. In the absence of antidiuretic hormone, the collecting ducts are virtually impermeable to water, and it flows out as urine. Antidiuretic hormone stimulates water reabsorbtion by stimulating insertion of "water chan-nels," or aquaporins, into the membranes of kidney tubules. These channels transport solute-free water through tubular cells and back into blood, leading to a decrease in plasma osmolarity and an increased osmolarity of urine. The most important variable regulating antidiuretic hormone secretion is plasma osmo-larity, or the concentration of solutes in blood. Osmolarity is sensed in the hypothalamus by neurons known as an osmoreceptors, and those neurons, in turn, simulate secretion from the neurons that produce antidiuretic hormone. Secretion of antidiuretic hormone is simulated by decreases in blood pressure and volume, conditions sensed by stretch receptors in the heart and large arteries. Another potent stimulus of antidiuretic hormone is nausea and vomiting, both of which are controlled by regions in the brain with links to the hypothalamus. 1. Ethanol and caffeine decrease ADH release while nicotine increases its release. Notes 2. Sweating causes an increase in ADH, while drinking large amounts of water causes a decrease in ADH. 2. Hyposecretion of ADH results in diabetes insipidus (polyuria, polydipsia, and polyphagia). Diabetes insipidus would also result from the hypoactivity of the posterior pituitary gland.

Which of the following equations is correct? • Haloenzyme + cofactor = cohaloenzyme • Apoenzyme + cofactor = haloenzyme • Coenzyme + cofactor = enzyme • Coenzyme + apoenzyme = coapoenzyme

Apoenzyme + cofactor = haloenzyme Cofactors are organic molecules (coenzymes) or ions (usually metal ions) that are required for its activity. They may be attached either loosely or tightly (prosthetic group) to the enzyme. A cofactor binds with its associated protein (apoenzymes), which is functionally inactive, to form the active enzyme (haloenzyme).

Which of the following is a polyunsaturated fatty acid that is not considered essential (needed in the diet)? • Linoleic acid • Arachidonic acid • Linolenic acid • Stearic acid

Arachidonic The human body can produce all but two of the fatty acids it needs. These two, linoleic acid and linolenic acid, are widely distributed in plant oils. Essential fatty acids cannot be synthesized because humans lack the enzymes to place double bonds at certain positions (omega-3 and omega-6) and must therefore obtain them from the diet. All fatty acids are building blocks of phospholipids and glycolipids and are therefore needed for the synthesis of membranes. Cells derive energy from fatty acids through beta-oxidation. Fats can be classified by the number of double bonds between carbon atoms in their fatty acid molecules: • Saturated fat: contains no bonds between carbon atoms • Monounsaturated fat: has one double bond between carbon atoms Note: Most monounsaturated fatty acids are in the CIS (same-side) form. • Polyunsaturated fat: has multiple double bonds between carbon atoms

Fatty Acids Types Saturated: Monounsaturated: Polyunsaturated:

Arachidonic acid Caprylic acid Behenic acid Lauric acid Butyric acid Myristic acid Capric acid Palmitic acid Caproic acid Stearic acid Erucic acid Oleic acid Palmitoleic acid Arachidonic acid Linoleic acid Linolenic acid

In eukaryotes, DNA does not exist free; it is complexed with an approximately equal mass of basic proteins called histones. These histones contain a large portion of: • Cysteine and lysine • Arginine and lysine • Lysine and glutamine • Glutamine and arginine

Arginine and lysine The nucleus contains the chromosomes of the cell. Each chromosome consists of a single molecule of DNA complexed with an equal mass of proteins. Collectively, the DNA of the nucleus with its associated proteins is called chromatin. Most of the protein consists of multiple copies of 5 kinds of histones (HI, H2A, H2B, H3, and H4). These are basic proteins, bristling with positively charged arginine and lysine residues. Important: Both Arg and Lys have a free amino group on their R group, which attracts protons (H+), giving them a positive charge (perfect amino acids to bind tightly to the negatively-charged phosphate groups of DNA). Note: These histones help neutralize the large negative charge of the DNA phosphate groups and stabilize DNA in a compact form. Remember: Histones package and order the DNA into structural units called nucleosomes. Nucleosomes are repeating subunits of chromatin, consisting of a DNA chain coiled around a core of histones. 1. Chromatin also contains small amounts of a wide variety of nonhistone proteins. Most of these are transcription factors (e.g., the steroid recept¬ors) and their association with the DNA is more transient. 2. Activation of DNA for replication or transcription requires breakup of the nucleosome structure. Phosphorylation of serine and threonine residues in histones is part of the process for replication, while acetylation of lysine residues in the histones is used for transcriptional activation.

The molecule picture below plays a major role: ) • As an energy source • As a membrane component • As a signal mechanism • Two of the above • All of the above

As an energy source -- it is a triglyceride A triglyceride is a naturally occurring ester of three fatty acids and glycerol that is the chief constituent of fats and oils. Triglycerides provide more than half the energy requirements of some organs, particularly the liver, heart, and skeletal muscle. Note: Triglycerides are not membrane constituents as are phospholipids and steroids. Triglycerides play an important role in metabolism as energy sources. Triglycerides contain twice as much energy (8000 kcal/kg) as carbohydrates. In the intestine, triglycerides are split into glycerol and fatty acids (with the help of lipases and bile secretions), which can then move into blood vessels. The triglycerides are rebuilt in the blood from their fragments and become constituents of lipoproteins. Various tissues can release the free fatty acids and take them up as a source of energy. Fat cells can synthesize and store triglycerides. When the body requires fatty acids as an energy source, the hormone glucagon signals the breakdown of the triglycerides by hormone-sensitive lipase to release free fatty acids. In the human body, high levels of triglycerides in the bloodstream have been linked to atherosclerosis, and, by extension, to the risk of heart disease and stroke. However, the negative impact of raised levels of triglycerides is lower than that of LDL-cholesterol. The risk can be partly accounted for a strong inverse relationship between triglyceride level and HDL-cholesterol level. Pancreatitis can also be caused by high triglyceride levels.

Glutamate can by synthesized by the addition of ammonia to a-ketoglutarate. All of the following amino acids can be derived from glutamate EXCEPT one. Which one is the EXCEPTION? • Asparagine • Glutamine • Proline • Arginine

Asparagine Synthesis of amino acids: • a-ketoglutarate gives rise to glutamate, which, in turn is the precursor of glutamine, proline, and arginine. • 3-phosphoglycerate gives rise to serine, which, in turn, is the precursor of glycine and cysteine. • Oxaloacetate gives rise to aspartate, which, in turn, is the precursor of asparagine, methionine, threonine, and lysine. Note: Threonine is the precursor of isoleucine. • Pyruvate gives rise to alanine, valine, leucine, and isoleucine. Note: Isoleucine can be formed by either pyruvate or threonine. • Phosphoenolpyruvate and erythrose-4-phosphate produce shikimate, which is converted to chorismate. Chorismate then gives rise to tryptophan, tyrosine, and phenylalanine. Note: Tyrosine is synthesized from phenylalanine in humans. • Ribose-5-phosphate gives rise to histidine.

The Bainbridge reflex, also called the reflex, is an increase in heart rate due to an increase in the blood volume. • Ventricular • Atrial • Mitral • Semilunar

Atrial The Bainbridge reflex is an increase in heart rate caused by a rise in pressure of the blood in the right atrium due to increased flow and/or pressure in the great veins at right atrium's entrance. This reflex increases the heart rate and cardiac output, which then transfers blood volume from the pulmonary circulation to the systemic circulation. Note: Receptor cells in the right atrium are sensitive to pressure and stretch. This reflex helps prevent the accumulation of blood in the pulmonary circulation, which could lead to pulmonary edema. The baroreceptor reflex is the dominant cardiovascular mechanism responsible for con¬trol of blood pressure. Stretch receptors located in the carotid sinus and aortic arch send afferent impulses via the glossopharyngeal and the vagus nerves to the nucleus solitar¬ius located in the cardiovascular center of the medulla. The baroreceptor reflex plays a dominant role during acute blood loss and shock.

Which of the following is not a recognized type of a second messenger? • Cyclic AMP • Protein kinases • Phosphoinositides • Cyclic GMP • Azidothymidine

Azidothymidine Cyclic GMP (cGMP) and cyclic AMP (cAMP) are second messengers that carry signals from the cell surface to proteins within the cell. These "second messenger" molecules intervene between the original message (the neurotransmitter or hormone) and the ultimate effect on the cell. Frequently, they act to stimulate protein kinases, and they are rapidly broken down in cells (to terminate response) by enzymes called phosphodiesterases. Currently, four second messenger systems are recognized in cells. Note: Not only do multiple hormones utilize the same second messenger system, but a single hormone can also utilize more than one system. Important: Hormones that utilize second messengers are usually water soluble peptide/protein hormones. 1. Azidothymidine is a treatment for HIV. Notes 2. cAMP is formed from ATP in a reaction catalyzed by adenylate cyclase. 3. Adenylate cyclase is an integral protein of the plasma membrane.

Amino acids are joined together in proteins by peptide bonds. A peptide bond forms between the of one amino acid and the of the adjacent amino acid. j • Amino / amino • Carboxyl / carboxyl • Carboxyl / amino

carboxyl / amino A peptide bond is a chemical bond formed between two molecules when the carboxyl group of one molecule reacts with the amino group of the other molecule, thereby releasing a molecule of water. This is a condensation reaction and usually occurs between amino acids. The resulting CO-NH bond is called a peptide bond, and the resulting molecule is an amide. Important Characteristics of the Peptide Bond: • The bonds involving the a-carbon can rotate freely. • Unlike its components (the a-amino and a-carboxyl group), the components of the pep¬tide bond do not accept or give off protons; therefore it does not ionize at physiologic pH. • It is not cleaved by organic solvents or urea, but is susceptible to strong acids. They are extremely stable. • It is generally a trans bond (occurs in trans configuration as opposed to cis configura¬tion). • It is uncharged but polar. • Proline due to formation of a tertiary amine restricts the range of rotation of the a-carbon in the peptide bond. Remember: Another type of covalent bond that occurs in many proteins is the disulfide bond. It is formed from the sulfhydryl group (-SH) of each of two cysteine residues, to produce a cystine residue. It is widely thought that these strong, covalent bonds help stabilize the structure of proteins and prevent them from becoming denatured in the extracellular environment. Examples include the hormone insulin and the immunoglobulins. 1. A residue is a single amino acid unit within a polypeptide chain. 2. Cystine is an amino acid that is found in many proteins. 3 Hydroxyproline is a constituent of collagen, and is rarely found in any other protein. Hydroxyproline provides stability to the triple-helical structure of collagen via hydrogen bonding. 4. Glycine is the only non-chiral amino acid.

CA patient of yours presents with symptoms similar to Parkinson's disease. 11----e' claims that the physicians have not diagnosed him with Parkinson's because it was due to trauma. The trauma affected which part of his brain? • Pons • Parietal lobe • Basal ganglia (basal nuclei) • Thalamus

Basal ganglia In current usage, the phrase "basal ganglia" means the caudate nucleus, putamen, and globus pallidus. They are functionally important, at a minimum, for controlling voluntary movements and establishing postures. When the basal ganglia are altered, say in disorders like Parkinson's disease, Huntington disease, or Wilson disease, the person has unwanted movements, such as involuntary jerking movements of an arm or leg or spasmodic movement of facial muscles. The caudate nucleus and putamen along with the interposed anterior limb of the internal capsule are collectively known as the corpus striatum (i.e., striated body) because of their appearance. Similarly, the shape of the putamen and globus pallidus resembles a lens, and they are collectively called the lenticular nucleus. The basal ganglia and cerebellum are large collections of nuclei that modify movement on a minute-to-minute basis. The cerebral (motor) cortex sends information to both, and both structures send information back to the cortex via the thalamus. The basal ganglia are located deep to the cerebral cortex. Note: The output of the cerebellum is excitatory, while the basal ganglia are inhibitory. Remember: The cerebellum is situated below and posterior to the cerebrum and above the pons and medulla. It is morphologically divided into two lateral hemispheres and a middle portion. Its function is to maintain equilibrium and muscle coordination. Note: The major parts of the extrapyramidal system are the "subcortical nuclei." This includes the caudate nucleus, putamen, and globus pallidus (which are also known as the basal ganglia).

Your practice is in an area where polished rice is a major component of the diet. Because of this, many of your patients present with thiamin deficiency syndrome. This is also called: • Pellagra • Beriberi • Scurvy • Megaloblastic anemia

Beriberi Thiamin, also called vitamin B1, is used in many different body functions and defic- iencies may have far-reaching effects on the body, yet very little of this vitamin is stored in the body, and depletion of this vitamin can happen within 14 days. Thiamin is also a miraculous nutrient. Somebody suffering from beriberi, scarcely able to lift his head from his pillow, will respond quickly to injected thiamin, and will be on his feet within a matter of hours. Thiamin may enhance circulation, and helps with blood formation and the metabolism of carbohydrates. It is also required for the health of the nervous system and is used in the biosynthesis of a number of cell constituents, including the neurotransmitter acetylcholine and gamma-aminobutyric acid (GABA). It is used in the manufacture of hydrochloric acid, and therefore plays a part in digestion.

Trpatient of yours lists a selective beta-blocker in her medication list. You know that this is for her hypertension. What is the mechanism of this drug? • Blocks beta-1 adrenergic receptors in the heart, causing a decrease in heart rate and force of contraction • Blocks beta-2 cholinergic receptors in the heart, causing a decrease in heart rate and force of contraction • Blocks beta-1 cholinergic receptors in the heart, causing a decrease in heart rate and force of contraction • Blocks beta-2 adrenergic receptors in the heart, causing a decrease in heart rate and force of contraction

Blocks beta-1 adrenergic receptors in the heart, causing a decrease in heart rate and force of contraction Beta-blockers "block" the effects of adrenaline on the body's beta receptors. This slows the nerve impulses that travel through the heart. As a result, the heart does not have to work as hard because it needs less blood and oxygen. Beta-blockers also block the impulses that can cause an arrhythmia. The body has two main beta receptors: beta 1 and beta 2. • Some beta-blockers are selective, which means that they block beta-1 receptors more than they block beta-2 receptors. Beta 1 receptors are responsible for heart rate and the strength of your heartbeat. • Nonselective beta-blockers block both beta-1 and beta-2 receptors. Beta-2 receptors are responsible for the function of your smooth muscles. Adrenergic receptors are membrane receptor proteins located on autonomic effector organs that are regulated by catecholamines (epinephrine and norepinephrine). Two main types of adrenergic receptors: Alpha receptors: • Alpha 1: located on smooth muscle; produce excitation (contraction or constriction) • Alpha 2: located in presynaptic nerve terminals, platelets, fat cells, and the walls of the GI tract; produce inhibition (relaxation or dilation) Beta receptors: • Beta 1: located in the heart; produce excitation (increased HR, increased contract¬ility, etc.) • Beta 2: located on smooth muscle; produce relaxation (dilation) Important: 1. Norepinephrine stimulates mainly alpha receptors. 2. Epinephrine stimulates both alpha and beta receptors.

If a patient's SA and AV nodes fail, what is the most likely situation the patient will be in? • Dead; the patient's heart will fail immediately • Both the atria and ventricles will continue to contract on the pace of the bundle of His (30-40 impulses) • The ventricles will contract and passively fill, keeping the pateint alive for a short period • The atria will take over and contract; the ventricles will allow the blood to flow through and out to the periphery of the body

Both the atria and ventricles will continue to contract on the pace of the bundle of His (30-40 impulses) The bundle of His is located in the proximal intraventricular septum. The bundle of His emerges from the AV node to begin the conduction of the impulse from the AV node to The AV node together with the bundle of His make up the AV junctional tissue. The AV junctional tissue is considered supraventricular (above the ventricles). The AV junctional tissue has an intrinsic rate of 40-60 beasts per minute. If the SA nodes are injured, AV junctional tissue can take over control of heart rate and rhythm. The bundle of His branches into the three bundle branches: the right, left anterior-su¬perior and left posterior-inferior bundle branches that run along the interventicular septum. The three bundle branches comprise the trifascicular system. The bundles give rise to thin filaments known as Purkinje fibers. These fibers distribute the impulse to the ventricular muscle. Collectively, the bundle branches and Purkinje net¬work comprise the ventricular conduction system. It takes about 0.03-0.04 seconds for the impulse to travel from the bundle of His to the ventricular muscle. Remember: The ventricular conducting system is capable of intrinsic pacemaker activ¬ity at a rate of 30-40 impulses per minute. If the SA and AV nodes are injured, the ven¬tricular conducting system can take over control of heart rate and rhythm.

Which of the following is not an oncogene? • HER-2/neu • ras • myc • strc • CAAT

CAAT *** CAAT is the binding site for RNA transcription factors. An oncogene is a defective gene that is involved in triggering cancer cell growth. Oncogenes are altered forms of genes (proto-oncogenes) that normally are involved in stimulating cell division. These normal genes are mutated and function in an inappropriate manner in cancer cells. Important: One or more oncogenes are mutant in all forms of cancer. Note: A proto-oncogene is a gene that has functions to promote cell division. When these genes are mutated, defective versions of these genes are formed (oncogenes), which may produce products that promote cell division in an abnormal fashion. A key feature of oncogene activity is that a single altered copy leads to unregulated growth. This is in contrast with tumor suppressor genes, which must both be def¬ective to lead to abnormal cell division. The following selected oncogenes have been associated with numerous cancer types: • HER-2/neu: a growth factor receptor -- it has been identified in up to 30% of human breast cancers. • ras: a signal transduction molecule -- it has been identified in cancers of many dif-ferent origins, including pancreas (90%), colon (50%), lung (30%), thyroid (50%), bladder (6%), ovarian (15%), breast, skin, liver, kidney, and some leukemias. • myc: a transcription factor -- mutations in the myc gene have been found in many different cancers, including Burkitt's lymphoma, B-cell leukemia, and lung cancer. • src: a protein tyrosine kinase -- it was the first oncogene ever discovered. It has been identified in human neuroblastoma, small-cell lung cancer, colon and breast carcino-mas, and rhabdomyosarcoma.

aVenous return (VR) is the flow of blood back to the heart. Under steady-statN conditions, venous return must equal when averaged over time because the cardiovascular system is essentially a closed loop. • S V • CO • HR • BP

CO -- cardiac output *** Otherwise, blood would accumulate in either the systemic or pulmonary circulations. Al-though cardiac output and venous return are interdependent, each can be independently regu¬lated. The circulatory system is made up of two circulations (pulmonary and systemic) situated in se¬ries between the right ventricle (RV) and left ventricle (LV). Balance is achieved, in large part, by the Frank-Starling mechanism. For example, if systemic venous return is suddenly in¬creased (e.g., changing from upright to supine position), right ventricular preload increases, leading to an increase in stroke volume and pulmonary blood flow. The left ventricle experiences an increase in pulmonary venous return, which in turn increases left ventricular preload and stroke volume by the Frank-Starling mechanism. In this way, an increase in venous return can lead to a matched increase in cardiac output. I. Preload is the muscle length prior to contractility, and is dependent of ventricu-lar filling (or end diastolic volume). This value is related to right atrial pressure. The most important determining factor for preload is venous return. 2. Afterload is the tension (or the arterial pressure) against which the ventricle must contract. If arterial pressure increases, afterload also increases. Afterload for the left ventricle is determined by aortic pressure; afterload for the right ventricle is deter¬mined by pulmonary artery pressure. 3. Increases in heart rate will also increase cardiac output, EXCEPT at very high heart rates where there will be less time for filling. 4. Sympathetic activation of the heart will increase heart rate, conduction velocity in the heart, and contractility of the cardiac muscle. 5. Venous return from the legs (peripheral venous return) is achieved by the pumping of the calf muscles with the help of efficient venous valves that prevent backflow of venous blood.

Cardiac function is the volume of blood pumped each minute, and is expressed by which equation? • CO = SV - HR • CO = SV + HR • CO = SV x HR • CO = SV / HR

CO = SV x HR Where: • CO is cardiac output expressed in L /min • SV is stroke volume per beat • HR is the number of beats per minute Cardiac output (CO) is perhaps the single most important factor that is used in relation to the circulation, for it is the CO that is responsible for transport of substances to and from the tissues. The average resting cardiac output is about 5.6 liters per minute for men and 10% to 20% less for women. CO varies depending upon the level of body activity, age, body size, condition of the heart, etc. Heart Rate (HR) is directly proportional to cardiac output; an adult HR is normally 80-100 beats per minute (bpm). Heart rate is an intrinsic factor of the SA (pacemaker) node in the heart, and is modified by autonomic, humoral, and local factors. Stroke Volume (SV) is determined by three factors: preload, afterload, and contractility. The preload gives the volume of blood that the ventricle has available to pump, as well as the end diastolic length of the muscle. The contractility is the force that the muscle can create at the given length, and the afterload is the arterial pressure against which the muscle will contract. SV = End Diastolic Volume - End Systolic Volume *** The average SV is 70 to 80 ml Important: The cardiac output of the left and right sides of the heart is equal. Blood ejected from the left side of the heart to the systemic circulation must be oxygenated by passage through the pulmonary circulation. Total peripheral resistance (TPR) is the sum of the resistance of all peripheral vasculature in the systemic circulation.Thus we have the equation, BP = CO x TPR. This is one of the fundamental equations of cardiovascular physiology. You can see from the equation that blood pressure can be maintained by altering cardiac output and/or total peripheral resistance.

Parafollicular, or, C cells in the thyroid gland are the major source of: ) • Gastrin • Calcitonin • Glucagon • Parathyroid hormone

Calcitonin Calcitonin is a hormone known to participate in calcium and phosphorus metabolism. In mammals, the major source of calcitonin is from the parafollicular, or, C cells in the thyroid gland. Calcitonin has the ability to decrease blood calcium levels at least in part by effects on two target or¬gans: • Bone: Calcitonin suppresses resorption of bone by inhibiting the activity of osteoclasts, a cell type that "digests" bone matrix, releasing calcium and phosphorus into blood. • Kidneys: Calcium and phosphorus are prevented from being lost in urine by reabsorption in the kidney tubules. Calcitonin inhibits tubular reabsorption of these two ions, leading to increased rates of their loss in urine. The most prominent factor controlling calcitonin secretion is the extracellular concentration of ionized calcium. Elevated blood calcium levels strongly stimulate calcitonin secretion, and secretion is sup-pressed when calcium concentration falls below normal. Note: Calcitonin is not required in adult humans. Although it is important during bone development, the major regulator of plasma calcium levels in the adult is parathyroid hormone. Thus, while an increase in the secretion of parathyroid hormone will increase plasma calcium levels, as parathyroid secretion decreases, plasma calcium will also decrease.

Which of the following changes happen in the synaptic cleft upon transmission of an action potential? • Calcium decreases, acetylcholine increases, sodium decreases • Calcium increases, acetylcholine decreases, sodium decreases • Calcium increases, acetylcholine increases, sodium decreases • Calcium decreases, acetylcholine decreases, sodium decreases • Calcium increases, acetylcholine increases, sodium increases • Calcium increases, acetylcholine decreases, sodium increases • Calcium decreases, acetylcholine increases, sodium increases

Calcium decreases, acetylcholine increases, sodium decreases *** Calcium influxes into the presynaptic cell, acetylcholine is released from the post-synaptic cell, and sodium influxes into the postsynaptic cell. An axon terminal of a presynaptic neuron closely approaches a dendrite or cell body of a postsynaptic neuron; however, the two cells are separated by a small synaptic cleft. Neurotransmitters are stored within the axon terminal of a presynaptic neuron in synaptic vesicles. When an action potential depolarizes the presynaptic membrane, voltage-gated calcium channels are opened, causing an increase in intracellular calcium. Calcium causes the synaptic vesicles to empty the neurotransmitter molecules into the synaptic cleft. These neurotransmitters diffuse across the synaptic cleft and bind to specific receptors on the postsynaptic cell. This process is called synaptic transmission, and the time required is called the synaptic delay. The final step is enzymatic deactivation of the neurotransmitter through conformational change or removal from the synaptic cleft. A synapse is an anatomical junction between two neurons where the depolarization of the presynaptic cell initiates a response in the postsynaptic cell. The most common type of synapse is a chemical synapse, which consists of: • Presynaptic membrane: synaptic vesicles within this terminal contain a neuro-transmitter • Synaptic cleft: space between the presynaptic and postsynaptic cells • Postsynaptic membrane: membrane of postsynaptic neuron that contains specific receptors for the neurotransmitter

The method of measuring heat loss or energy loss is called: • Enthalpy • Hydropathy index • Calorimetry • Entropy

Calorimetry Putting a person in a tank of water and noting the temperature change in the water can measure human body heat. The body heat causes this change. Direct calorimetry -- the measurement of the amount of heat made by the body's processes. This is a method of measuring energy released by the cells. Important: Oxidative reactions (e.g., evaporation, radiation, conduction, and convection) produce heat. Human calorie use can also be measured in terms of the amount of oxygen inhaled and the amount of carbon dioxide exhaled during a given time. This is called indirect calorimetry. Remember: • Enthalpy is the heat content of a system • Entropy is a physical value that describes the degree of order of a system ***The second law of thermodynamics states that in any chemical or physical process, the entropy of the universe tends to increase. The second law is based on human experience. The law doesn't come from complicated theory and equations. So, think of these experiences that you have had: A rock will fall if you lift it up and then let go. Hot frying pans cool down when taken off the stove. Iron rusts (oxidizes) in the air. Air in a high-pressure tire shoots out from even a small hole in the side to the lower pressure atmosphere. Ice cubes melt in a warm room. What's happening in every one of those processes? Energy of some kind is changing from being localized ("concentrated" somehow) to becoming more spread out. That's the fundamental science behind the second law: Energy spontaneously disperses from being localized to becoming spread out if not hindered.

Which of the following serves as a principal source of _--. carbon for nonessential amino acids? • Fats • Water • Carbohydrates • Urea

Carbohydrates *** Ten of the nonessential amino acids contain carbon skeletons that can be derived from glucose. Note: Tyrosine, the 11th nonessential amino acid, is synthesized by hydroxylation of the essential amino acid phenylalanine. Remember: The nonessential amino acids are synthesized in mammals and generally are those with simple pathways. Nonessential amino acids are not needed in the diet. They include glutamate, glutamine, proline, arginine, serine, glycine, cysteine (carbon skeleton only), aspartate, asparagine, alanine, and tyrosine. Important: Nonessential amino acids can be synthesized from the corresponding a-keto acids, an a-amino acid (as the NH3+ donor), a specific transaminase enzyme, and the coenzyme pyridoxal phosphate (vitamin B6). These amino acids include alanine, aspartate, and glutamate. The other nonessential amino acids are synthesized by amidation (glutamine and asparagine). Note: Although cysteine's carbon skeleton can be formed from carbohydrates, cysteine requires the essential amino acid methionine to supply the sulfhydryl group.

The precursor for steroid hormones is: • Insulin • Glue agon • Cholesterol • Somatostatin

Cholesterol Steroid hormones are crucial substances for the proper function of the body. They mediate a wide variety of vital physiological functions ranging from anti-inflammatory agents to regu¬lating events during pregnancy. Steroid hormones are synthesized and secreted into the blood¬stream by endocrine glands such as the adrenal cortex and the gonads (ovary and testis). Steroid hormones are all characterized by the steroid nucleus, which is composed of three six-member rings and one five-member ring. Cholesterol is a sterol, which is a natural product derived from the steroid nucleus. In addition to being the building block for steroid hormones, cholesterol is also a component of the cell membrane. It is thought that the cholesterol present in the cell membrane is responsible for al¬lowing steroid hormones to enter the cell, bind to the hormone receptor, and ultimately to a spe¬cific site on the chromatin, in turn activating the gene in question. Five classes of steroid hormones: 1. Androgens: originate in the adrenal cortex and gonads and primarily affect maturation and function of secondary sex organs (male sexual determination). 2. Estrogens: originate in the adrenal cortex and gonads and primarily affect maturation and function of secondary sex organs (female sexual determination). 3. Progestins: originate from both ovaries and placenta, and mediate the menstrual cycle and maintain pregnancy. 4. Mineralocorticoids: originate in adrenal cortex and maintain salt and water. 5. Glucocorticoids: originate in the adrenal cortex and affect mainly metabolism in di-verse ways; decrease inflammation and increase resistance to stress. The production and secretion of steroid hormones are controlled by trophic hormones, which themselves are either proteins or peptides. Steroid hormones, which are non-polar molecules, simply pass through the plasma mem-branes of their target cell to the cytosol where they bind to their respective receptors. The steroid hormone penetrates the cell membrane and moves through the cytoplasm to the nu-cleus; it then couples with the receptor protein, forming a hormone receptor complex.

All of the following statements are true EXCEPT one. Which one is the EXCEPTION? • Preganglionic neurons have their cell bodies in the CNS and synapse in autonomic ganglia • Sympathetic ganglia are located in the paravertebral chain • Cholinergic neurons, whether in the sympathetic or parasympathetic nervous system, release norepinephrine as the neurotransmitter • The majority of sympathetic postganglionic neurons are noradrenergic

Cholinergic neurons, whether in the sympathetic or parasympathetic nervous system, release norepinephrine as the neurotransmitter *** This is false; cholinergic neurons, whether in the sympathetic or parasympathetic nervous system, release acetylcholine as the neurotransmitter. Important Points to Remember: Autonomic nervous system: Synapses between neurons are made in the autonomic ganglia. 1. Sympathetic ganglia: are located in the paravertebral chain or prevertebral ganglia. 2. Parasympathetic ganglia: are located in or near the effector organs. Two Types of Motor Neurons: 1. Preganglionic neurons: have their cell bodies in the CNS and synapse in autonomic ganglia. • Preganglionic neurons of the sympathetic nervous system originate in spinal cord segments T1- L2. • Preganglionic neurons of the parasympathetic nervous system originate in the nuclei of cranial nerves in spinal cord segments S2 - S4. *** These preganglionic neurons of both the sympathetic and parasympathetic systems are cholinergic, which means they release acetylcholine as the neurotransmitter. 2. Postganglionic neurons of both the sympathetic and parasympathetic systems have their cell bodies in the autonomic ganglia and synapse on effector organs. *** Parasympathetic postganglionic neurons are cholinergic; the majority of sympathetic postganglionic neurons are noradrenergic, which means they release norepinephrine as the neurotransmitter.

All of the following statements about plasma lipoproteins are false EXCEPT one. Which one is the EXCEPTION? • Chylomicrons are synthesized in the intestinal mucosal cells and transport triacylglycerol to the peripheral tissues. • HDL particles are produced from LDL particles in the circulation by the action of lipoprotein lipase. • HDL competes with LDL for binding to receptors on the surface of cells in extrahepatic tissues. • LDL particles have the least percentage concentration of cholesterol.

Chylomicrons are synthesized in the intestinal mucosal cells and transport triacylglycerol to the peripheral tissues. Chylomicrons are plasma lipoproteins consisting of a large droplet of triacyl¬glycerols that are stabilized by a coat of protein and phospholipid. Chylomicrons carry fatty acids obtained in the diet to the tissues in clyomicrons they are consumed or stored as fuel. The remnants of chylomicrons, depleted of their triacylglycerols (triglycerides) but still containing cholesterol, move through the bloodstream to the liver, where they are taken up, degraded in lysosomes, and their constituents recycled. Note: Chylomicrons are the least dense of the blood lipoproteins because chylomicrons have the most triacylglycerols and the least protein content. Remember: Lipoproteins are lipid-binding proteins, responsible for the transport in the blood of triglycerides, phospholipids, cholesterol, and cholesterol esters from the liver to tissues or organs. Other lipoproteins include the following: • Very low-density lipoproteins (VLDL): these contain a high concentration of triglycerides and moderate concentrations of both phospholipids and cholesterol. • Low-density lipoproteins (LDL): are very rich in cholesterol. They are the major cholesterol carrier in the blood and are derived from VLDL. • High-density lipoproteins (HDL): are protein rich with relatively little free cholesterol; most of the cholesterol is present as acyl ester derivatives. 1. HDL particles are produced de novo in the liver. 2. HDL and LDL particles each have their own specific binding sites on cell membranes -- HDL on the liver, and LDL on the liver and extrahepatic tissues. 3. Lovastatin ("statin" drug) lowers blood cholesterol levels by inhibiting HMG CoA reductase, a key regulatory enzyme in cholesterol biosynthesis.

Which of the following is not a possible immediate fate of pyruvate as it comes out of glycolysis? • Lactate • Acetyl-CoA • Oxaloacetate • Ethanol • Citrate

Citrate -- it becomes oxaloacetate first The possible fates of pyruvate: Conversion to lactate: lactate dehydrogenase (LDH) converts pyruvate into lactate cytosol. This is the major fate for pyruvate in red blood cells, the lens and cornea of the eye, the medulla of the kidney, the testes, and leukocytes. Conversion to acetyl-CoA: pyruvate dehydrogenase converts pyruvate to acetyl-CoA in the mitochondria. This acetyl-CoA can then enter the citric acid cycle or be used as the building block for fatty acid synthesis. Conversion to oxaloacetate: pyruvate carboxylase converts pyruvate to oxaloacetate. This reaction replenishes the citric acid cycle intermediates and provides substrate for gluconeogenesis. Note: Pyruvate carboxylase is found in the liver and kidney, but not in muscle. Pyruvate derived from glycolysis would not provide a substrate for gluconeogenesis -- a futile, ATP-wasting cycle would result. Conversion to ethanol: pyruvate is reduced to ethanol. This occurs in yeast and certain microorganisms, but not in humans.

Summary of Vitamin C Dietary Sources Major Body Functions Deficiency

Citrus fruits, tomatoes, green peppers, broccoli, spinach, strawberries, melon Synthesis of connective tissues. Essential for the hydroxylation of lysine and praline in collagen synthesis Essential for integrity for capillaries and oral mucosa Needed for normal bone matrix formation Needed for normal phagocytic function and antibody synthesis in host defense system Scurvy (degeneration of skin, teeth, blood vessels, epithelial hemorrhages) Delayed wound healing Anemia

Growth and preparation of the chromosomes for replication occurs in which phase of the cell cycle? • G1 • Go • S • G2 • M

Cl The cell cycle is an ordered set of events, culminating in cell growth and division into two daughter cells. The stages are G1- S - G2 - M. • The G1 stage stands for "GAP 1" • The S stage stands for "Synthesis" (the stage when DNA replication occurs) • The G2 stage stands for "GAP 2" • The M stage stands for "Mitosis" (the stage when nuclear chromosomes separate and cytoplasmic (cytokinesis) division occur). Mitosis is further divided into 4 phases: (telophase, interphase, metaphase, and anaphase) The cell cycle consists of the following: • G1 = growth and preparation of the chromosomes for replication • S = synthesis of DNA (and centrosomes) • G2 = preparation for mitosis • M = mitosis The period between M and S is called G1; that between S and M is G2. Note: Many times a cell will leave the cell cycle, temporarily or permanently. The cell exits the cycle at G1 and enters a stage designated Go (G zero). Many Go cells are busy carrying out their functions in the organism (e.g., secretion, attacking pathogens). Important: Protein and RNA synthesis occur in all phases of the cell cycle except M (mitosis). A eukaryotic cell cannot divide into two, the two into four, etc. unless two processes alternate: • doubling of its genome (DNA) in S phase (synthesis phase) of the cell cycle. • halving of that genome during mitosis (M phase).

Which of the following is a water-soluble vitamin and in contrast to other water-soluble vitamins is not excreted quickly in the urine, but rather accumulates and is stored in the liver, kidney, and other body tissues? j • Vitamin A • Cobalamin (vitamin B12) • Niacin • Vitamin E • Riboflavin

Cobalamin (vitamin B12 ) --- also called cyanocobalamin As a result, a vitamin B12 deficiency may not manifest itself until after 5 or 6 years of a diet supplying inadequate amounts. Vitamin B12 functions as a methyl donor and works with folic acid in the synthesis of DNA and red blood cells and is vitally important in maintaining the health of the myelin sheath that surrounds nerve cells. The classical vitamin B12 deficiency disease is pernicious anemia, a serious disease characterized by large, immature red blood cells. 1. Deficiency is usually owing to the absence of intrinsic factor, which is Notes produced in the stomach. Intrinsic factor is necessary for the absorption of vitamin B12 from the GI tract. 2. It is the only vitamin that contains essential mineral elements and is the first substance containing cobalt that is found to be vital to life. 3. It may be present in inadequate quantities in a strictly vegetarian diet.

Which of the following is involved in both fatty acid catabolism and synthesis? • Carnitine • Coenzyme A • Malonyl-CoA • Alcohol dehydrogenase

Coenzyme A *** Carnitine = catabolism, Malonyl-CoA = synthesis, alcohol dehydrogenase = neither Fatty Acid Catabolism (summary): The fatty acid is transported to the liver by employing carnitine as a carrier substance. Once inside the mitochondria, the fatty acid is transferred from the carnitine to a CoA and is oxidized (via beta oxidation) to acetyl-CoA. The acetyl-CoA molecules enter into the citric acid cycle (Krebs cycle) to form carbon dioxide and reducing equivalents (NADH, FADH2). The reducing equivalents are then reoxidized by electron transport system, and the energy released by that process is used by the oxidative phosphorylation system to form ATP. Important: Fatty acids are the predominant source of ATP for moderate levels (lasting longer than 1 hour) of activity. Biosynthesis of Fatty Acids (summary): This occurs in the cytosol. It involves two carbon additions from acetyl-CoA and an acyl protein (ACP). A key intermediate in the synthesis of fatty acids is malonyl¬CoA, which is formed from acetyl-CoA, bicarbonate, and ATP. This irreversible reaction is the committing step in fatty acid synthesis. Remember: During fatty acid biosynthesis, the following are expected to be active -- the Krebs cycle, glycolysis, amino acid catabolism and the enzyme pyruvate dehydrogenase (catalyzes the oxidative decarboxylation of pyruvate, to form acetyl-CoA). Coenzyme A (CoA) is a pantothenic acid-containing coenzyme that is Notes involved in both fatty acid synthesis and catabolism. 2. Acetyl-CoA is a common intermediate of the metabolism of not only fatty acids but also amino acids and carbohydrates.

A patient of yours presents with scurvy in his medical history. The production of which of the following proteins would be most directly affected by this condition? • Elastin • Microtubules • Collagen • Thrombin • Fibrin

Collagen *** Scurvy is caused by a deficiency of vitamin C. The hydroxylation of proline and lysine residues in collagen requires vitamin C and oxygen. Collagen is 35% glycine, 21% proline, and 11% alanine. Hydroxyproline and hydroxylysine are also present. The basic structural unit of collagen is tropocollagen. Tropocollagen is the longest known protein and is formed from procollagen, which is secreted by fibroblasts. Tropocollagen is also present in reticulin, which is a component of reticular fibers. Note: Mature collagen lacks aromatic and sulfur-containing amino acids. Almost a third of all the protein found in the body is collagen. Each collagen molecule consists of three polypeptide chains that are wound tightly around each other to give a triple helix. This gives the molecule a structure that is very resistant to stretching, a vital property, for example, for its functions in tendons and as a component of the matrix of bone and cartilage. Remember: Vitamin C influences the formation of collagen, which is the organic matrix found in dentin and cementum. See note #1 below. 1. Hydroxyproline and hydroxylysine are nonstandard amino acids that are present in few other proteins. For this reason, their concentration in a particular tissue is a good estimate of the collagen content as well. They are not used directly in the reactions of protein synthesis. These amino acids are formed by the hydroxylation of proline and lysine. This hydroxylation involves a-ketoglutarate, oxygen, and vitamin C (ascorbic acid). 2. Collagen and reticular fibers make up the stroma of all lymphoid tissues except the thymus.

Which of the following makes up most of the organic components of the bone? • Collagen secreted by osteoblasts • Glycosaminoglycans secreted by osteoblasts • Collagen secreted by osteocytes • Glycosaminoglycans secreted by osteocytes

Collagen secreted by osteoblasts The organic part of bone matrix is mainly composed of type I collagen. Osteoblasts are mononucleate bone-forming cells that descend from osteoprogenitor cells. Osteoblasts are located on the surface of osteoid seams and make a protein mixture known as osteoid, which mineralizes to become bone. Osteoid is primarily composed of type I collagen. The intercellular matrix of bone contains both organic components (glycosamino-glycans in the ground substance and collagen fibers) and inorganic salts. The inorganic salts consist primarily of calcium phosphate, which is present in the form of highly insoluble crystals of hydroxyapatite. The collagen fibers provide bone with great tensile strength, while the inorganic salts allow bone to withstand compression. Note: Bone is an important calcium reservoir. Some of the common glycosaminoglycans present in the intercellular matrix of bone include hyaluronic acid and chondroitin sulfate. The intercellular matrix also contains a calcium-binding protein called osteocalcin as well as a calcium and collagen-binding protein called osteonectin. Age, race, and gender affect bone mass, structural integrity, and bone loss. For example, blacks commonly have denser bones than whites, and men commonly have denser bones than women. Point to remember: Bone density and structural integrity (ability to withstand stress) decrease after age 30 in women and 45 in men. Thereafter, a rela¬tively steady quantitative loss of bone matrix occurs.

Which electron-carrier complex of the respiratory chain uses NADH as the electron donor? • Complex I • Complex II • Complex III • Complex IV

Complex I The majority of the energy conserved during catabolism reactions occurs near the end of the metabolic series of reactions in the electron transport chain. The electron transport or respiratory chain gets its name from the fact that electrons are transported to meet up with oxygen from respiration at the end of the chain. There are four electron-carrier complexes, each representing a fraction of the entire respiratory chain. Each of the four separate complexes has its own unique composition, and each is capable of catalyzing electron transfer through a portion of the chain. Complexes I and II catalyze electron transfer to ubiquinone from two different electron donors: NADH (Complex I) and succinate/FADH2 (Complex II). Complex III carries electrons from ubiquinone to cytochrome c, and Complex IV completes the sequence by transferring electrons from cytochrome c to oxygen.

Saltatory conduction happens in myelinated neurons only. Which TWO of the following are effects of saltatory conduction compared to conventional conduction? • Conduction is faster • Conduction is slower • Conduction is at the same rate • Conduction consumes more energy • Conduction consumes less energy • Conduction consumes the same energy

Conduction is faster Conduction consumes less energy In an unmyelinated neuron, the impulse travels along the entire membrane surface and is known as continuous conduction. Note: This conduction is relatively slow (1.0 m/sec) compared to saltatory conduction (up to 100 m/sec). In a myelinated neuron, the myelin sheath decreases membrane capacitance and increases membrane resistance, preventing movement of sodium and potassium through the membrane. If the myelin sheath were continuous, action potentials could not be produced. However, the myelin sheath is interrupted by nodes of Ranvier. The distance between these nodes is between 0.2 and 2 mm. Action potentials traveling down the axon "jump" or "leap" from node to node. This is called saltatory conduction. Saltatory conduction is of value for two reasons: 1. Increases velocity of nerve transmission in myelinated fibers. 2. Conserves energy for the axon because only the node depolarizes. Thus, it takes less energy for the sodium/potassium ATPase to re-establish resting ion gradients. Important point: Saltatory conduction is not only faster but also consumes less energy, since the pumping of sodium and potassium ions need occur only at the nodes. Conduction velocity depends on: 1. Diameter of the nerve fiber. An increase in diameter reduces resistance to cur-rent flow down the axon. 2. Presence of myelin sheath.

Which of the following is not a function of the autonomic nervous system? • Innervation of all visceral organs • Transmission of sensory and motor impulses • Regulation and control of vital activities • Conscious control of motor activities • Two of the above are not functions

Conscious control of motor activities Important: The actions of the autonomic nervous system (ANS) are largely involuntary (in contrast to those of the somatic system). The ANS also differs from the somatic system in using two efferent neurons from the CNS to the effector. The central nervous system (CNS) = spinal cord + brain The peripheral nervous system (PNS) = afferent neurons from sensory receptors to the CNS + efferent neurons from the CNS to the muscles, organs, and glands. The PNS is subdivided into the: • Somatic nervous system: consists of 12 pairs of cranial nerves and 31 pairs of spinal nerves; consists of both sensory and motor neurons; innervates the skeletal muscle and includes sensation of touch, movement, temperature, and pain. • Autonomic nervous system: has two main subdivisions: 1. Sympathetic nervous system 2. Parasympathetic nervous system The enteric nervous system is a third division of the autonomic nervous system that you do not hear much about. The enteric nervous system is a meshwork of nerve fibers that innervate the viscera (gastrointestinal tract, pancreas, and gall bladder). *** Preganglionic neurons arise in the CNS and run to autonomic ganglia in the body. Here they synapse with postganglionic neurons, which run to the effector organ (cardiac muscle, smooth muscle, visceral organs, or glands).

Nutrient/Mineral Functions Iron Iodine Calcium Phosphorus Sulfur Potassium Sodium Magnesium Cobalt Copper

Constituent of hemoglobin and enzymes involved in energy metabolism Constituent of thyroid hormones, regulates energy metabolism Bone and tooth formation, blood clotting nerve transmission, muscle contraction Bone and tooth formation, acid-base balance, release of energy (ADP, ATP) Constituent of active tissue compounds, cartilage and tendon Acid-base balance, body water balance, nerve function, muscle relaxation Acid-base balance, body water balance, nerve function Activates enzymes involved in protein synthesis Constituent of vitamin B12 Constituent of enzymes associated with iron metabolism and nerve function

Enzymes of Glycolysis Hexokinase Phosphoglucose isomerase Phosphofructokinase Aldolase Triose phosphate isomerase Glyceraldehyde 3-phosphate dehydrogenase Phosphoglycerate kinase Phosphoglyceromutase Enolase Pyruvate kinase

Converts glucose into glucose-6-phosphate Converts glucose-6-phosphate into fructose-6-phosphate Converts fructose-6-phosphate into fructose 1,6-bisphosphate Converts fructose 1,6-bisphosphate into dihydroxyacetone phosphate and glyceraldehyde 3-phosphate Converts dihydroxyacetone phosphate into glyceraldehyde 3-phosphate Converts glyceraldehyde 3-phosphate into 1,3-bisphosphoglycerate Converts 1,3-bisphosphoglycerate into 3-phosphoglycerate Converts 3-phosphoglycerate into 2-phosphoglycerate Converts 2-phosphoglycerate into phosphoenolpyruvate Converts phosphoenolpyruvate into pyruvate

Which of the following is a part of active cytochrome oxidase? • Zinc • Vitamin C • Copper • Vitamin K • Magnesium

Copper Cytochrome oxidase is one of a superfamily of proteins that act as the terminal enzymes of respiratory chains. Copper is also important in the maturation of collagen and elastin as copper is a cofactor for the enzyme lysyl oxidase. The oxidized lysine residues formed in collagen and elastin by this enzyme form the cross-links that stabilize these molecules. Minerals are inorganic substances that are essential to life. They serve both structural and regulatory functions. Minerals may be classified as: • Major minerals (more than 0.005% of body weight) -- calcium, chloride, magn¬esium, phosphorus, potassium, sodium, and sulfur. • Trace minerals (less than 0.005% of body weight) -- chromium, cobalt, copper, fluoride, iodine, iron, manganese, molybdenum, selenium, and zinc. General Functions of Minerals: • Maintenance of acid-base balance • Coenzymes or catalysts for biologic reactions • Components of essential body compounds • Transmission of nerve impulses and regulation of muscle contractions • Maintenance of water balance • Growth of oral and other body tissues

Which of the following is the metabolic pathway in which lactate produced by anaerobic glycolysis in the muscles moves to the liver and is converted to glucose, which then returns to the muscles and is converted to glycogen? • Hydrologic cycle • Cori cycle • Carbon cycle • Glucose cycle

Cori cycle --- sometimes referred to as the "lactic acid cycle" Lactate is released into the blood by cells that lack mitochondria, such as red blood cells, and by exercising skeletal muscle. In the Cori cycle, blood-borne glucose is converted by exercising muscle to lactate, which diffuses into the blood. This lactate is taken up by the liver and converted to glucose, which is released back into the circulation. See diagram below. The cycle's importance is based on the prevention of lactic acidosis in the muscle under anaerobic conditions. The accumulation of lactic acid causes muscle pain and cramps; however, normally before this happens the lactic acid is moved out of the muscles into the liver. The cycle is also important in producing ATP, an energy source, during muscle activity. The Cori cycle functions more efficiently when muscle activity has ceased because the oxygen debt can be made up so that the citric acid cycle and electron transport chain also work.

The brain has two motor systems: (1) the voluntary or pyramidal motor system that moves your muscles under the direction of the mind and (2) the extra-pyramidal systems that control muscle tone, posture, and motor activity without conscious thought. The voluntary or pyramidal motor system is located in the: j • Cortex • Brain stem • Dural sinuses • Cerebellum

Cortex *** The extra-pyramidal motor system, centered in the basal ganglia, relies on dopamine to maintain proper muscle tone and motor stability. The Pyramidal Tract: This group of fibers carries messages for voluntary motor move-ment one skilled movements of skeletal muscle) to the lower motor neurons in the brain stem and spinal cord. Approximately 80% of the cell bodies of the pyramidal tract are located on the precentral gyrus of the frontal lobe, which is also known as the motor strip. Approxi¬mately 20% of the pyramidal tract fibers also originate in the postcentral gyms of the parie¬tal lobe, in Brodmann's areas 1, 2, and 3. This tract is direct and monosynaptic, meaning that the axons of its neurons do not synapse with other cells until they reach their final destination in the brain stem or spinal cord. These direct connections between the cortex and the lower motor neurons allow messages to be transmitted very rapidly from the central nervous system to the periphery. The fibers of the pyramidal tract that synapse with cranial nerves located in the brain stem form the corticobulbar tract. This is the part of the pyramidal tract that carries the motor messages that are most important for speech and swallowing. The fibers of the pyramidal tract that synapse with spinal nerves sending information about voluntary movement to the skeletal muscles form the corticospinal tract. At the pyramids in the inferior part of the medulla, 85% to 90% of corticospinal fibers decussate, or cross to the other side of the brain. The remaining 10% to 15% continue to descend ipsilaterally. The fibers that decussate are called the lateral corticospinal tract or the crossed pyramidal tract. Because they descend along the sides of the spinal cord, the uncrossed or direct fibers that synapse with spinal nerves on the ipsilateral side of the body are called the direct pyramidal tract. They may also be referred to as the ventral pyramidal tract or the anterior corticospinal tract since they travel down the ventral aspect of the spinal cord

Tracts descending to the spinal cord are concerned with voluntary motor function, muscle tone, reflexes, equilibrium, visceral innervation, and modulation of ascending sensory signals. The largest and most important of these tracts is: • Rubrospinal tract • Vestibulospinal tract • Reticulospinal tract • Corticospinal tract

Corticospinal tract Universally regarded as the single most important tract concerned with skilled voluntary activity, the corticospinal tract originates from pyramid-shaped cells in the premotor, primary motor, and primary sensory motor.

All of the following bonds are considered to be weak bonds EXCEPT one. Which one is the EXCEPTION? • Hydrogen bonds • Ionic bonds • Covalent bonds • van der Waals forces Weak bonds are involved in all of the following EXCEPT one. Which one is the EXCEPTION? • Secondary structure of proteins • Cell membrane • dsDNA structure • Amino acid linkage

Covalent bonds Amino acid linkage Covalent bonds are the strongest possible type of chemical bond. Other chemical bonds include ionic bonds, hydrogen bonds, and the van der Waals force. There are numerous other types of rare and exotic bonds, but the first four are by far the most common. Covalent bonds are created between atoms with similar electronegativity. In general, electronegativity increases as you move to the right of the periodic table and decreases as you move down the periodic table. Electronegativity is not an atomic property, but emerges when atoms interact with other atoms. Covalent bonds are forces that hold atoms together. The forces are formed when the atoms of a molecule share electrons. Two examples of covalent bonds are peptide and disulfide bonds. Note: Hydrogen, oxygen, nitrogen, and carbon are capable of forming one, two, three, and four covalent bonds, respectively. Carbon is very versatile and can form covalent single, double, and triple bonds. Weak bonds may be easily broken but are very important because they help to determine and stabilize the shapes of biological molecules. For example weak bonds are important in stabilizing the secondary structure (a-helix and (3 sheets) of proteins. Hydrogen bonds keep complementary strands of DNA together and participate in enzymatic catalysis. These interactions are individually weak but collectively strong. Note: Denaturing agents (organic solvents, urea, and detergents) act primarily by disrupting the hydrophobic interactions that make up the stable core of globular proteins.

All of the following are sources of acetyl-CoA for fatty acid synthesis EXCEPT one. Which one is the EXCEPTION? J • Creatinine • Pyruvate • Glucose • Citrate

Creatine *** Glucose is the major source of acetyl-CoA for fatty acid synthesis. Acetyl-CoA for fatty acid synthesis comes mostly from the glycolytic breakdown of glucose when high amounts of glucose are consumed -- a high carbohydrate diet. Fatty acid synthesis occurs primarily in the cytoplasm of the liver, and lactating mammary gland and, to a lesser extent, in adipose tissue and kidney. Important points to remember for fatty acid synthesis: • Glucose is first degraded to pyruvate by aerobic glycolysis in the cytoplasm. • Pyruvate is then transported into the mitochondria, where pyruvate dehydrogen¬ase oxidatively decarboxylates pyruvate, forming acetyl-CoA and other products. • Acetyl-CoA can then serve as a substrate for citrate synthesis. • Citrate, in turn, can be transported out of the mitochondria to the cytoplasm (where fatty acid synthesis occurs), and there citrate splits to generate cytoplasmic acetyl-CoA for fatty acid synthesis. Summary of fatty acid synthesis: Acetyl-CoA —> Malonyl-CoA —> Malonyl-ACP-* Acetyl-ACP-* Acetoacetyl-ACP--> Butyryl-ACP-* Fatty acid *** The carboxylation of acetyl-CoA to form malonyl-CoA is catalyzed by acetyl¬CoA carboxylase (an allosteric enzyme that is the principal regulator of the pathway). Remember: Malonyl-CoA is the three-carbon intermediate that participates in the biosynthesis of fatty acids but not in their breakdown.

Second Messenger Examples of Hormones That Use This System

Cyclic AMP Protein kinase activity Calcium and/or phosphoinosites Cyclic GMP Epinephrine and norepinephrine, glucagon, luteinizing hormone, follicle-stimulating hormone, thyroid-stimulating hormone, calcitonin, parathyroid hormone, antidiuretic hormone Insulin, growth hormone, prolactin, oxytocin, erythropoietin, several growth factors Epinephrine and norepinephrine, angiotensin II, antidiuretic hormone, gonadotropin-releasing hormone, thyroid-releasing hormone Atrial naturetic hormone

A patient of yours has a dietary deficiency of choline. Which of the following would not be related to this condition? • Decreased speed of electrical impulses • Disrupted water balance function in the kidney • Decreased metabolism of triglycerides • Decreased surfactant in the lung • Decreased muscle control • Decreased intestinal absorption

Decreased intestinal absorption Although choline is not by strict definition a vitamin, choline is an essential nutrient. Although humans can synthesize choline in small amounts, it must be consumed in the diet to maintain health. The majority of the body's choline is found in specialized fat molecules known as phospholipids, the most common of which is called phosphatidylcholine or lecithin. Functions of choline: • Contributes to the proper structure and function of cell membranes. Choline is found as phosphatidylcholine (or lecithin) in the phospholipid bilayer of cell membranes. • As part of the sphingomyelin that makes up the myelin sheath, choline insulates nerve fibers and aids in the rapid conduction of electrical impulses. • Choline is a precursor of betaine, an osmolyte used by the kidney to control water balance. • Choline functions in the liver as a source of methyl groups required for lipoprotein formation and for the synthesis of methionine from homocysteine. • Choline is necessary for the synthesis of acetylcholine, an important neurotransmitter involved in memory storage and muscle control. • Choline is an active component of surfactant in the lung. Neonate surfactant def-iciency leads to respiratory distress syndrome in premature infants. Note: A deficiency of choline in the diet can cause abnormalities in the metabolism of fats and can lead to fatty liver disease and eventually hepatic cirrhosis.

c A patient of yours has uncontrolled diabetes mellitus. This causes ketosis, or high levels of ketone bodies in the body tissues and fluid. Which of the following is not a symptom of this condition? • Fruity breath • Lowered pH of the blood • Decreased potassium in the urine • Ketone bodies in the urine

Decreased potassium in the urine Ketosis is a condition characterized by an abnormally elevated concentration of ketone bodies in the body tissues and fluids. Ketosis occurs when fatty acids are incompletely metabolized, a complication of untreated diabetes mellitus, starvation, fasting, and alcoholism. It is characterized by ketones in the urine (ketonuria), ketone bodies in the blood (ketonemia), potassium loss in the urine, and a fruity odor of acetone on the breath. Important: Ketosis can lead to ketoacidosis (two of the ketone bodies are acids that cause lowering of blood pH. 1. A diabetic coma can be caused by the buildup of ketone bodies. It is commonly fatal, unless appropriate therapy is instituted promptly. Glucose is effective in reversing ketosis in a non-diabetic patient. 2. Acetone is not utilized by the body as a fuel. 3. In a healthy diet, most acetyl-CoA is processed through the citric acid cycle. During fasting, the normal balance between carbohydrate and fatty acid metabolism is disrupted, and activity of the citric acid cycle is reduced. Then someof the acetyl-CoA produced from fats will be converted to ketone bodies.

Glucagon has all of the following actions EXCEPT one. Which one is the EXCEPTION? • Increases plasma glucose • Increases plasma free fatty acids and ketoacids • Decreases plasma amino acids • Increases urea production

Decreases plasma amino acids *** Important: Insulin, not glucagon, decreases plasma amino acids. The most important function of glucagon is its ability to cause glycogenolysis (conversion of glycogen to glucose) in the liver, which, in turn, increases plasma glucose. For this reason, glucagon is found in emergency medical kits. It can be used on an emergency patient who has diabetes and is suffering from hypoglycemia. Note: It does not stimulate glycogen degradation in muscle. Glucagon is secreted by the alpha cells in the islets of Langerhans of the pancreas in response to a fall in the blood glucose level. Glucagon is frequently called the hyperglycemic factor. Glucagon has many of the opposite effects of insulin. Note: Insulin is secreted in response to a rise in the blood glucose level and causes glycogenesis in the liver (conversion of glucose to glycogen). Glucagon release by alpha cells is promoted by the following: • A fall in blood glucose level (hypoglycemia) -- this is the major regulator of glucagon release. • Sympathetic stimulation • Epinephrine, norepinephrine secretion • Elevated level of amino acids (especially arginine) in the blood plasma • Cholecystokinin secretion Factors that decrease glucagon secretion -- a rise in blood glucose level, insulin, somatostatin, free fatty acids, and ketoacids.

When you administer local anesthetics to your patients, what effect does this have on the nerve membrane? • Increases potassium flux • Increases the membrane excitability by increasing the membrane's permeability to sodium ions • Decreases the membrane's permeability to sodium ions and reduces the membrane excitability • Increases the calcium and chloride flux

Decreases the membrane's permeability to sodium ions and reduces the membrane excitability Local anesthetics bind to the inactivation gates of fast voltage-gated sodium channels, stabilizing them in a closed position, effectively prolonging the absolute refractory period. This decreases sodium membrane permeability, and therefore reduces membrane excitability. When the excitability has been reduced below a critical level, a nerve impulse fails to pass through the anesthetized area. Potassium, calcium, and chloride conductances remain unchanged. Local anesthetics reversibly block nerve impulse conduction and produce reversible loss of sensation at their administration site. Small, myelinated nerve fibers, which conduct pain and temperature sensations, are affected first, followed by touch, proprioception, and skeletal muscle tone.

Changes in vessel are most important quantitatively for regulating blood flow within an organ, as well as for regulating arterial pressure. • Thickness • Length • Diameter

Diameter Resistance to blood flow within a vascular network is determined by the size of individ¬ual vessels (length and diameter), the organization of the vascular network (series and parallel arrangements), physical characteristics of the blood (viscosity, laminar flow ver¬sus turbulent flow), and extravascular mechanical forces acting upon the vasculature. Changes in vessel diameter, particularly in small arteries and arterioles, enable organs to adjust their own blood flow to meet the metabolic requirements of the tissue. Therefore, if an organ needs to adjust its blood flow (and therefore, oxygen delivery), cells surround¬ing these blood vessels release vasoactive substances that can either constrict or dilate the resistance vessels. The ability of an organ to regulate its own blood flow is termed local regulation of blood flow and is mediated by vasoconstrictor and vasodilator substances released by the tissue surrounding blood vessels (vasoactive metabolites) and by the vascular endothelium. There is also a mechanism intrinsic to the vascular smooth muscle (myogenic mechanism) that is involved in local blood flow regulation. In organs such as the heart and skeletal muscle, mechanical activity (contraction and re-laxation) produces compressive forces that can effectively decrease vessel diameters and increase resistance to flow during muscle contraction.

( Which pathway is depicted to the right? ) • Entner-Doudoroff pathway • Embden-Meyerhof pathway • Pentose phosphate pathway • Urea pathway

E mbden-Meyerhof pathway The Embden-Meyerhof pathway is a specific glycolytic pathway by which glucose is converted to pyruvate. This is the most common pathway and is used by a large number of anaerobic and facultatively anaerobic bacteria. Important: Oral bacteria use this pathway. The pyruvate is reduced to lactic acid via fermentation. This lactic acid is cariogenic. Note: This glycolytic pathway results in the net production of 2 ATP molecules per molecule of glucose metabolized. The Entner-Doudoroff pathway is also a glycolytic pathway used by many obligate aerobic bacteria. It results in the net production of only one ATP molecule per molecule of glucose metabolized by substrate level phosphorylation compared to the 2 formed in the Embden-Meyerhof pathway. The pathway ends with the formation of a pyruvate and a glyceraldehyde-3-phosphate -- which is converted by enzymes outside the pathway to pyruvate. Note: These bacteria lack either of the key enzymes 6-phosphofructokinase or aldolase of the Embden-Meyerhof pathway. The pentose phosphate pathway (also called the pentose shunt, the hexose monophosphate pathway, or the phosphogluconate pathway) is a pathway of hexose oxidation whereby glucose-6-phosphate generates five-carbon sugars. This pathway plays a major role in the production of NADPH for reductive biosynthesis (e.g., of fatty acids).

All of the following statements are true EXCEPT one. Which one is the EXCEPTION? • One-third of elastin's amino acids are glycine • Elastin is one of the few places to find hydroxyproline • Lysine is involved in elastin cross-links • Elastin is one of the few places to find hydroxylysine

Elastin is one of the few places to find hydroxylysine Elastin is rich in small, nonpolar aliphatic residues such as glycine (1/3 of all residues), proline, alanine, valine, leucine, and isoleucine. Elastin contains a small amount of hydroxyproline (non-standard amino acid; derivative of proline) and no hydroxylysine. In contrast to collagen, which forms fibers that are tough and have high tensile strength, elastin is a connective tissue protein with rubber-like properties. Elastic fibers can be stretched to several times their normal length -- it is the elastin that gives these fibers the capacity of returning to their original lengths after being stretched. These fibers are found in the skin, ligaments, and the walls of arteries, where the fibers' elastic properties are important. 1. The polypeptide subunit of elastin fibrils is tropoelastin. Notes 2. Elastin fibers are formed as a three-dimensional network of cross-linked polypeptides. The cross-links involve lysine and oxidized lysine residues (allysine), which are covalently linked to produce a desmosine cross-link 3. The oxidation of lysine residues in both collagen and elastin is an extra-cellular process catalyzed by lysyl oxidase (a copper requiring enzyme).

Which of the following does not help to maintain the resting membrane potential of a resting neural cell? • Resting potassium conductance • Sodium/potassium pump • Electron transport chain • All of the above

Electron transport chain The electron transport chain is used in respiration and is located on the inner mitochon¬drial membrane, moving hydrogen ions into the intermembrane space. Resting membrane potential (RMP) results from an excess of positive ions on the outer surface of the plasma membrane. More Na' ions are on the outside of the membrane than K' ions are on the inside of the membrane. The size of the resting membrane potential varies but in excitable cells runs between (-) 40 and (-) 85 millivolts. The resting membrane potential arises from two activities: 1. There is a resting potassium conductance that allows positive charges to leave the cell down their electrochemical gradient. In most excitable cells, this is the most important determinant of RMP. 2. The sodium/potassium pump establishes the sodium and potassium gradients across the membrane using ATP. This pump is electrogenic, i.e., it exchanges two potassium ions (K+) into the cell for every three sodium ions (NO it pumps out of the cell, resulting in a net loss of positive charges within the cell. Nearly one-third of all resting energy expenditure is spent maintaining the proper Na+/K+ gradient. Note: Visceral smooth muscle and cardiac pacemaker cells lack a stable resting membrane potential.

Amino Acids: Essential (Indispensable) vs. Nonessential (Dispensable)

Essential (Indispensable) Histidine Isoleucine Leucine Lysine Methionine Phenylalanine Threonine Tryptophan Valine Nonessential (Dispensable) Alanine Arginine Asparagine Aspartic acid Cysteine Glutamic acid Glutamine Glycine Proline Serine Tyrosine

Solution options • Isotonic • Hypotonic • Hypertonic Match the scenario to the solution options. Scenarios • A solution that when placed on the outside of the cell will cause osmosis out of the cell • A solution that when placed on the outside of the cell wall will cause osmosis into the cell • A solution that when placed on the outside of the cell will not cause osmosis

• Isotonic -- A solution that when placed on the outside of the cell will not cause os-mosis • Hypotonic -- A solution that when placed on the outside of the cell wall will cause osmosis into the cell • Hypertonic -- A solution that when placed on the outside of the cell will cause os-mosis out of the cell An isotonic solution is a solution that has the same salt concentration as the normal cells of the body and the blood. This solution, when placed on the outside of a cell, will not cause osmosis and the cell will not shrink or swell. Note: Either a 0.9% solution of sodium chloride or a 5% glucose solution is both approximately isotonic to plasma. A hypertonic solution is a solution with a higher salt concentration than in normal cells of the body and the blood. This solution, when placed on the outside of a cel,l will cause osmosis out of the cell and lead to shrinkage of the cell. Note: Sodium chloride solutions of greater than 0.9% concentration are all hypertonic. A hypotonic solution is a solution with a lower salt concentration than in normal cells of the body and the blood. This solution, when placed on the outside of a cell, will cause osmosis into the cell and lead to swelling and lysis of the cell. Note: Any solution of sodium chloride with less than 0.9% concentration is hypotonic. Isotonic solutions have the same solute concentrations as each other. If isotonic solutions are separated by a partially permeable membrane, the water potential will be the same on either side. There will be no net osmotic movement of water between the two solutions. The amount of water that moves in one direction will be exactly balanced by the amount that moves back in the other.

When the ambient temperature is above body temperature, which heat transfer mechanism(s) is (are) used by the body to transfer energy from the body to the environment? • Radiation • Conduction • Convection • Evaporation of perspiration • All of the above

Evaporation of perspiration When the ambient temperature is above body temperature, then radiation, conduction, and convection all transfer heat into the body rather than out. Since there must be a net outward heat transfer, the only mechanisms left under those conditions are the evaporation of perspiration from the skin and the evaporative cooling from exhaled moisture. The human body has the remarkable capacity for regulating its core temperature somewhere between 98°F and 100°F when the ambient temperature is between approximately 68°F and 130°F. The temperature of the body is regulated by neural feedback mechanisms that operate primarily through the hypothalamus. The hypothalamus contains not only the control mechanisms but also the key temperature sensors. Under control of these mechanisms, sweating begins almost precisely at a skin temperature of 37°C and increases rapidly as the skin temperature rises above this value. The heat production of the body under these conditions remains almost constant as the skin temperature rises. If the skin temperature drops below 37°C, a variety of responses are initiated to conserve the heat in the body and to increase heat production. These include: vasoconstriction to decrease the flow of heat to the skin, cessation of sweating, shivering to increase heat production in the muscles and the secretion of norepinephrine, epinephrine, and thyroxine to increase heat production. *** Shivering is the most potent mechanism for increasing heat production. Radiation is heat transfer by the emission of electromagnetic waves that carry energy away from the emitting object. Conduction is heat transfer by means of molecular agitation within a material without any motion of the material as a whole. Convection is heat transfer by mass motion of a fluid such as air or water when the heated fluid is caused to move away from the source of heat, carrying energy with it.

Which of the following is the best-known stimuli for increasing the rate of thyroid-stimulating hormone (TSH) secretion by the anterior pituitary gland? '---...— • Exposure to heat • Exposure to cold • Exposure to stress • Exposure to relaxation

Exposure to cold Thyroid-stimulating hormone (TSH), also called thyrotropin, is secreted by basophils of the pars distalis of the anterior pituitary gland. TSH controls the rate of secretion of thyroid hormones (thyroxine and triiodothyronine). Thyroxine, in turn, controls the rates of many metabolic processes and the metabolic rate. Various types of stress can inhibit TSH secretion, most likely by way of neural influences that inhibit the secretion of thyrotropin-releasing hormone (TRH) from the hypothalamus. Remember: TSH secretion is stimulated by TRH. There are several negative feedback loops that regulate the secretion of thyroid hormones, including the following: 1. High levels of circulating thyroid hormone decreass the secretion of both TRH and TSH. 2. Elevated levels of TSH decreases the secretion of TRH. 1. Hypersecretion of TSH results in Graves' disease. Notes 2. Hyposecretion of TSH results in cretinism (in young people) or myxedema (in adults).

Which motor system is affected in your patient who has limited facial expression due to Parkinson's disease? • Pyramidal system • Extrapyramidal system

Extrapyramidal system This system is involved in automatic motor movements, and in gross rather than fine movement. Facial expression is one important communicative behavior that is mediated by the extrapyramidal tract. Note: This is the reason that some Parkinson patients have little facial expression. In contrast to the pyramidal tract, the extrapyramidal tract is an indirect multisynaptic tract. The extrapyramidal nuclei include the substantia nigra, basal ganglia (caudate, puta-men, and globus pallidus), thalamus, red nucleus, and subthalamic nucleus. All of these nuclei are synaptically connected to one another, the brainstem, the cerebellum and the pyramidal system. Note: The substantia nigra is located in the midbrain. It is partic-ularly affected in Parkinson's disease. Extrapyramidal tracts include: • The rubrospinal tract originates in the red nucleus. The cerebellum sends messages to the spinal nerves along this tract. Information flows from the superior cerebellar peduncle to the red nucleus and finally to the spinal nerves. This information is very important for somatic motor, or skeletal muscle control, and the regulation of muscle tone for posture. • The reticulospinal tract originates in the reticular nuclei of the pons and medulla to the spinal nerves. The tract is involved in somatic motor control like the rubrospinal tract and plays an important role in the control of autonomic functions. • The tectospinal tract has points of origin throughout the brain stem, but especially in the midbrain area, and ends in the spinal nerves. The tract is involved in the control of neck muscles. • The vestibulospinal tract originates in the vestibular nuclei located in the lower pons and medulla to the spinal nerves. This tract is involved in balance.

fAll of the following statements concerning fatty acid synthesis are true EXCEPT one. Which one is the EXCEPTION? • Fatty acid synthesis involves two carbon additions primarily from acetyl-CoA • The important step in fatty acid synthesis is the first one in which acetyl-CoA, ATP, and bicarbonate form malonyl-CoA • Fatty acid synthesis is not a simple reversal of B-oxidation used for the catabolism of fatty acids • Fatty acid synthesis takes place in the mitochondria while fatty acid breakdown (catabolism) occurs in the cytosol (cytoplasm)

Fatty acid synthesis takes place in the mitochondria while fatty acid breakdown (catabolism) occurs in the cytosol (cytoplasm) *** This is false; fatty acid synthesis takes place in the cytosol while fatty acid breakdown (catabolism) occurs in the mitochondria. A fat, or triglyceride, contains three molecules of fatty acid combined with one molecule of glycerol. A fatty acid is a long-chain compound with an even number of carbon atoms and a terminal COOH group. Fatty acids can be saturated (no double bonds), monounsaturated (has one double bond between carbon atoms), or polyunsaturated (has multiple double bonds between carbon atoms). Remember: In humans, fatty acid synthesis occurs primarily in the liver. The "tail" of a fatty acid is a long hydrocarbon chain, making it hydrophobic. The "head" of the molecule is a carboxyl, group which is hydrophilic. Fatty acids are the main component of soap, where their tails are soluble in oily dirt and their heads are soluble in water to emulsify and wash away the oily dirt. However, when the head end is attached to glycerol to form a fat, that whole molecule is hydrophobic. Lipids are organic compounds that do not dissolve in water but do dissolve in alcohol and other organic solvents. The major lipids include triacylglycerols (the most common lipids), phospholipids, and steroids.

Some enzymes containing/requiring inorganic elements as cofactors Cofactor and ebzymes

Fe2+ or Fe3+ Cu2+ Zn2+ mg2+ mn2+ K+ Ni2+ Mo Se Cytochrome oxidase Catalase Peroxidase Ferredoxin Cytochrome oxidase Pyruvate phosphokinase Carbonic anhydrase Alcohol dehydrogenase Hexokinase Glucose-6-phosphatase Pyruvate kinase Arginase Ribonucleotide reductase Pyruvate Urease Dinitrogenase Glutathione peroxidase

eWhich of the following is not one of the three mechanisms the body uses to control the blood's acid-base balance? • Excess acid is excreted by the kidneys • pH buffers are found in the blood • Excretion of carbon dioxide • Filtering blood by the spleen

Filtering blood by the spleen The three mechanisms that the body uses to control the blood's acid-base balance are the following: 1. Excess acid is excreted by the kidneys, as hydrogen ion, ammonium ion, or combined with phosphate. 2. The body uses pH buffers in the blood to guard against sudden changes in acidity. The major blood buffers are bicarbonate, hemoglobin, and albumin. 3. In the excretion of carbon dioxide, the blood carries carbon dioxide to the lungs where it is exhaled. Respiratory control centers in the brain regulate the amount of carbon dioxide that is exhaled by controlling the speed and depth of breathing. Note: From the Henderson-Hasselbalch relationship, we can see how plasma pH is determined by the plasma levels of carbon dioxide and bicarbonate. The pKa of the bicarbonate-carbon dioxide buffer system is 6.1 pH = 6.1 + log [bicarbonate] / (0.03 X partial pressure of carbon dioxide) ***The 0.03 multiplier is the solubility constant of CO2 in blood. The multiplier converts the Pco2 measurement to CO2 concentration in mmol/L. This is necessary to ensure that both the HCO3 and CO2 concentration have the same units.

Which of the following contribute sympathetic fibers to the heart and increase cardiac function? • Right vagus nerve • First four thoracic spinal nerves (accessory nerves) • Left vagus nerve • Trigeminal nerve

First four thoracic spinal nerves (accessory nerves) Heart rate is controlled primarily by the autonomic nervous system -- sympathetic (norepinephrine) stimulation causes an increase in heart rate, and parasympathetic (acetylcholine) stimulation causes a decrease in heart rate. The main centers for autonomic cardiac control are located in the medulla oblongata of the brain stem. Sympathetic Cardiac Effects: 1. An increase in the rate of discharge of the sinoatrial node (S-A node). 2. An increase in the rate at which the depolarization spreads throughout the heart. The heart then contracts more uniformly, which increases its pumping effectiveness. 3. An increase in ICF (intracellular fluid) calcium, which increases the force of ventricular contractions. Parasympathetic fibers innervate the heart by way of the vagus nerves. The right vagus nerve goes to the SA node while the left vagus nerve goes to the AV node. Parasympathetic activation decreases heart rate and decreases the spread of depolarization from the atria to the ventricles. 1. The SA node is called the pacemaker of the heart. The rate of discharge of this node sets the rhythm for the entire heart. 2. The slowest rate of conduction is in the AV node. This results in a delay between atrial depolarization and ventricular depolarization, which allows the atria to pump blood into the ventricles.

Summary of Vitamin D Dietary Sources Major Body Functions Deficiency

Fish-liver oil, eggs, dairy products, fortified milk, margarine • Promotes growth and mineralization of bones and teeth • Calcium and phosphorus metabolism (bone formation) • Rickets in children • Osteomalacia in adults

Blood flow is directly proportional to the pressure difference between the two ends of the vessel but is inversely proportional to the fractional resistance to the blood flow through a vessel. This relationship can be expressed as: • Flow = pressure difference x resistance • Flow = pressure difference resistance • Flow = resistance pressure difference

Flow = pressure difference/resistance This relationship indicates that: 1) the greater the pressure gradient, the greater the flow rate; and 2) the flow rate decreases with increased resistance. Factors influencing resistance are expressed as: Resistance = viscosity (of blood) x length (of vessel) (radius)4 Important: The larger the vessel, the less the resistance --- Note: It is the fourth power of the radius. This means that if the radius is doubled the resistance will decrease by a factor of 16. Thus, the major physiological regulation of blood flow is via the activation of vascular smooth muscle (vasoconstriction). This fact explains why arterioles, with their ability to quickly constrict or dilate, are the most critical factor in controlling blood flow to peripheral tissues. Regulators of vascular smooth muscle include the sympathetic nervous system, circulating hormones, and local factors. Pressure is the driving force of the blood flow. When blood vessels are connected, the blood flows from the higher pressure site to the lower pressure site, and the rate of flow is proportional to the pressure difference. The overall pressure difference is between the ascending aorta and the entrance to the right atrium -- the circulatory pressure (about 100 mmHg).

Which of the following is a water-soluble vitamin that helps the body for red blood cells and aids in the formation of genetic material? • Vitamin A • Thiamin • Folacin • Pantothenic acid

Folacin folate, folic acid *** Folacin plays a key role in one-carbon metabolism, and is essential for the biosynthesis of the purines and the pyrimidine, thymine. 1. Folic acid is stored in the liver and may be synthesized by the bacterial Notes flora of the GI tract. 2. Folic acid deficiency is probably the most common vitamin deficiency in the U.S., particularly among pregnant women and alcoholics. 3. Because of folic acid's importance in the synthesis of purines and thymin,e the metabilism of folic acid metabolism is the target of a number of antimetabolite drugs such as methotrexate.

In the following list, find the two pairs of hormones that work on the same target organs. • Follicle-stimulating hormone • Oxytocin • Prolactin • Luteinizing hormone • Adrenocorticotropic hormone

Follicle-stimulating hormone: both work on the ovaries / testes Oxytocin and prolactin: both work on the mammary glands (oxytocin also works on the uterine smooth muscle)

Ketone body synthesis from acetyl-CoA occurs in: • Hepatic mitochondria • Skeletal muscle mitochondria • Kidney mitochondria • Cardiac muscle mitochondria

liepatic mitochondria Liver mitochondria have the capacity to divert any excess acetyl-CoA derived from fatty acid or pyruvate oxidation into ketone bodies. The compounds classified as ketone bodies are ace¬toacetate, 3-hydroxybutyrate (3-hydroxybutyrate), and acetone. Ketone body production is regulated primarily by availability of acetyl-CoA. During conditions of low glucose avail¬ability (a period of starvation or fasting, or a case of diabetes mellitus), the mobilization of fatty acids from adipose tissue is high, and hepatic beta-oxidation will occur at a high rate, and so will synthesis of ketone bodies from the resulting acetyl-CoA. These ketone bodies are then transported in the blood to peripheral tissues, where the ketone bodies can be recon¬verted to acetyl-CoA and oxidized by the citric acid cycle (Krebs cycle). They are important sources of energy for the peripheral tissues. Synthesis of ketone bodies by the liver is a three-step process: • The first step is formation of acetoacetyl-CoA in a reversal of the thiolase step of beta-oxidation. • In the second step, a third molecule of acetyl-CoA condenses with the acetoacetyl-CoA, forming 3- hydroxy-3-methylglutaryl CoA (HMG CoA) in a reaction catalyzed by HMG¬CoA synthase. Note: This enzyme, HMG-CoA synthase, is the rate-limiting step in the synthesis of ke¬tone bodies and is present in significant quantities only in the liver. • In the third step, HMG-CoA is cleaved to yield acetoacetate (a ketone body) in a reac¬tion catalyzed by HMG-CoA lyase (HMG-CoA cleavage enzyme). One molecule of acetyl¬CoA is also produced. Note: Acetoacetate can be reduced to form 3-hydroxybutyrate or can be spontaneously de¬carboxy lated to form acetate. 1. Ketone bodies are utilized exclusively by extrahepatic tissues; heart and Notes skeletal muscle use ketone bodies particularly effectively. Unlike fatty acids, ketone bodies can be oxidized by the brain. 2. The liver cannot reconvert acetoacetate to acetoacetyl-CoA, and therefore cannot itself use ketone bodies as fuels.

Three patients ingest three different substances. Match the substance to the description of the patient's urine. • Jim ate a substance that is filtered into the renal tubules but is then reabsorbed fully •Art ate a substance that is filtered and excreted, so the entire amount of substance was released in the first pass •Matt ate a substance that was freely filtered and neither secreted or reabsorbed •Glucose • Inulin • Para-aminohippurate (PAH) Which patient is being tested for his glomerular filtration rate (GFR)?) • Jim • Art • Matt

• Jim ate glucose • Art ate PAH • Matt ate inulin • Inulin was eaten by Matt, and he is being tested for his GFR Inulin is a starch that is given by mouth. Insulin is freely filtered from the glomerular capillaries into Bowman's capsule, but insulin does not undergo tubular secretion or reabsorption. The glomerular filtration rate (GFR) can be calculated by the clearance of inulin from plasma. The rate at which a substance is cleared from plasma = plasma volume completely cleared / unit time = (the urine concentration of the substance * urine volume) / plasma concentration of the substrate. Important: If the clearance of a substance that is freely filtrated is less than that of inulin, then there is a net reabsorption of the substance. If the clearance of a substance that is freely filtered is greater than that of inulin, then there is a net secretion of the substance. If the clearance of a freely filtered substance is equal to that of inulin, then (1) it is neither secreted nor absorbed or (2) it is both secreted and absorbed in equal amounts. 1. PAH is both filtered and secreted and is used to estimate renal plasma flow. Glucose and sodium chloride are filtered and subsequently reab¬sorbed. 2. Assessment of blood urea nitrogen (BUN) and serum creatinine can also be used to estimate the GFR. Some literature states that the most accur¬ate measure of GFR is creatine clearance. 3. If the amount of a substance excreted in the urine is less than the amount filtered, then the substance is reabsorbed.

The liver has a multitude of important and complex functions. These include all of the following EXCEPT one. Which one is the EXCEPTION? ,...__ • Manufacture (synthesize) proteins, including albumin • Synthesize, store, and process (metabolize) fats • Metabolize and store carbohydrates • Form and secrete bile • Form urine

Form urine *** This is a function of nephrons in the kidney. Hepatocytes (liver cells) are metabolic superachievers in the body. Their functions include the following: • Manufacture (synthesize) proteins, including albumin (to help maintain the vol-ume of blood) and blood clotting factors. • Synthesize, store, and process (metabolize) fats, including fatty acids (used for energy) and cholesterol. • Metabolize and store carbohydrates, which are used as the source for the sugar (glucose) in blood that red blood cells and the brain use. • Form and secrete bile that contains bile acids to aid in the intestinal absorption of fats and the fat-soluble vitamins A, D, E, and K. • Eliminate, by metabolizing and/or secreting, the potentially harmful biochemical products produced by the body, such as bilirubin from the breakdown of old red blood cells and ammonia from the breakdown of proteins. • Detoxify, by metabolizing and/or secreting, drugs, alcohol, and environmental toxins. Note: The nonessential amino acids can all be synthesized in the liver. To do this for most amino acids, an a-keto acid having the same chemical composition (except at the keto oxygen) as that of the amino acid is first synthesized. Then the amino radical is transferred through transamination from an available amino acid to the keto acid to take the place of the keto oxygen.

The pitch of a sound is related mainly to which of the following characteristics of a sound wave? f • Amplitude of the sound wave • Frequency of the sound wave • Superimposed wave • Secondary waves • Length of the sound wave

Frequency of the sound wave A sound can be characterized according to its pitch, loudness, and timbre (quality). As mentioned, the pitch is related to the frequency of the sound wave. In general, the higher the frequency of a sound wave, the higher the pitch of the sound wave. Note: Frequency is measured in hertz (Hz) or cycles per second. The loudness of a sound is related to the intensity and the amplitude of the wave. Usually, the greater the amplitude of a particular sound wave, the greater the intensity of the wave and the louder the sound. Note: Intensity is measured in decibels (dB). The timbre or quality of a sound is related to the presence of additional sound-wave frequencies superimposed on the principal frequency.

All of the following statements below concerning G proteins are false EXCEPT one. Which one is the EXCEPTION? • G proteins bound to GDP are inactive • Activation of a membrane receptor triggers an allosteric change in Ga, causing GTP to leave and be replaced by GDP • Adenylate cyclase activates G proteins and causes dissociation into a and 13y subunits • cAMP activates G proteins, leading to an exchange of GTP for GDP

G proteins bound to GDP are inactive The trimeric GTP binding proteins (G proteins) play a pivotal role in the signal transduction pathways for numerous hormones and neurotransmitters. The three subunits of the protein are labeled alpha, beta, and gamma. Both the alpha and gamma subunits are bound to the membrane via attached lipid molecules (related to fatty acids and cholesterol). The receptors are proteins with seven transmembrane alpha-helices. One example is the widespread epinephrine receptor. The binding of the hormone or neurotransmitter to the receptor causes GTP to replace GDP on the alpha subunit. As a result, the alpha subunit dissociates from the other two. Subsequently, the alpha subunit and the combined beta and gamma subunits move along the inner surface of the membrane to specific ion channels or membrane enzymes. Ion channels opened in this way are often potassium channels; an example of a membrane enzyme with this type of activation is adenylate cyclase. Important: The GTP-bound form of the a subunit moves from the receptor to adeny¬late cyclase, which is thus activated. 1. Activation of the receptor causes an exchange of GDP for GTP. Notes 2. The a subunit of G protein activates adenylate cyclase. 3. cAMP activates protein kinase A.

The most abundant inhibitory neurotransmitter in the central nervous system is: • Acetylcholine (A Ch) • Norepinephrine • Glycine • GABA • Dopamine • Glutamate • Serotonin

GABA Release of excitatory neurotransmitters from the presynaptic membrane opens channels in the postsynaptic membrane and leads to an increase in the concentration of sodium ions within the postsynaptic cell and a decrease in that of potassium ions. This leads to a depolarization of the postsynaptic cell, which is propagated further along the cell membrane by an action po¬tential. Inhibitory neurotransmitters encourage the hyperpolarization of the postsynaptic cell, mak¬ing it less likely to generate an action potential. Whether a neurotransmitter acts in an excitatory or inhibitory manner is determined by the re¬action of the receptor to its binding. Thus, a given chemical can be excitatory at some recep¬tors and inhibitory at others. Some examples of neurotransmitter action: Acetylcholine - voluntary movement of the skeletal muscles (via the sympathetic pathways) and movement of the viscera (via the parasympathetic pathways). Norepinephrine - wakefulness or arousal - via the sympathetic pathways. Epinephrine - similar to norepinephrine. Large amounts of it are produced and are released by the adrenal glands. Also called adrenaline. Dopamine - voluntary movement and motivation, "wanting," pleasure, associated with ad¬diction and love. Serotonin - memory, emotion, wakefulness, sleep, and temperature regulation. Glutamate - the most abundant excitatory neurotransmitter in the central nervous system. GABA - the most abundant inhibitory neurotransmitter in the central nervous system. Glycine - spinal reflexes and motor behavior. Histamine - involved in the sleep/wake cycle and inflammatory response. Also has a mod¬ulating action on norepinephrine, serotonin, and acetylcholine. Monoamine oxidase (MAO) is an enzyme that catalyzes the oxidative deamination of monoamines such as norepinephrine, serotonin, and epinephrine. This deamination process aids in metabolizing excess neurotransmitters that may build up at postsynaptic terminals.

(?) is the best overall index of kidney function. • CPR • TFR • APR • GFR

GFR The glomerular filtration rate (GFR) is the rate at which the glomeruli filter blood, normally about 120 ml/minute. GFR depends on: • Permeability of capillary walls • Vascular pressure • Filtration pressure • Clearance The GFR is increased by: • Vasodilation of afferent arterioles: increases the glomerular capillary hydrostatic pressure and increases renal blood flow (RBF). • Vasoconstriction of efferent arterioles: also increases the glomerular capillary hydrostatic pressure. • Decreased hydrostatic pressure in Bowman's capsule: blockage of urine trans¬port through the ureters will increase hydrostatic pressure in Bowman's capsule and cause a decrease in GFR. • Decreased plasma colloid osmotic pressure: associated with a decrease in the concentration of plasma proteins. Remember: • If the tubules neither reabsorb nor secrete the substance -- as happens with inulin or creatine -- clearance equals the GFR. • If the tubules reabsorb the substance, clearance is less than the GFR. • If the tubules secrete the substance, clearance exceeds the GFR. • If the tubules reabsorb and secrete the substance, clearance may be less than, equal to, or greater than the GFR. Note: Excessive constriction of the efferent arteriole will decrease RBF and GFR.

An old dental classmate of yours has been taking advantage of your free care for years. This time you see him, he tells you that all that drinking in dental school is catching up to him as his liver is failing. Which plasma proteins will be least affected? • Albumin • Alpha globulin • Beta globulin • Gamma globulin • Fibrinogen

Gamma globulins *** Gamma globulins (immunoglobulins) are globulins made by immune cells, specifically B-lymphocytes and their derivative plasma cells in the lymphoid system. All the plasma proteins are synthesized in liver except gamma globulins • 60% of plasma proteins are made up of the protein albumin, which are major con¬tributors to the osmotic pressure of plasma, which assists in the transport of lipids and steroid hormones. • Globulins make up 35% of plasma proteins and are used in the transport of ions, hor¬mones, and lipids assisting in immune function. • 4% is fibrinogen, and this is essential in the clotting of blood and can be converted into insoluble fibrin. • Regulatory proteins, which make up less than 1% of plasma proteins, are proteins such as enzymes, proenzymes, and hormones. Plasma proteins act as buffers that help stabilize the pH of the internal environment. Important point: Intracellular proteins absorb hydrogen ions generated by the body's metabolic processes. Note: Other plasma proteins include the following: 1. Lipoproteins (chylomicrons, VLDL, LDL, HDL) that are responsible for the transport in the blood of triglycerides, phospholipids, cholesterol, and cholesterol esters from the liver to tissues or organs. 2. Transferrin (for iron transport) 3. Prothrombin (a blood-clotting protein)

Which GI hormone has been referred to as glucose-dependent insulinotropic peptide? • Gastrin • Gastric inhibitory peptide (GIP) • Cholecystokinin (CCK) • Secretin

Gastric inhibitory peptide (GIP) *** Another activity of GIP is its ability to enhance the release of insulin in response to infusions of glucose. Gastric inhibitory peptide (GIP), like secretin, is secreted from mucosal cells in the first part of the small intestine (duodenum). GIP inhibits gastric acid secretion (HCL) and gastric motility and potentiates the release of insulin from beta cells in response to elevated blood glucose concentration. Note: GIP was initially called enterogastrone (which now refers to the group of enterogastric inhibitory hormones liberated from the duodenal mucosa). 1. GIP is synthesized by K cells, which are found in the mucosa of the duode¬num and the jejunum of the gastrointestinal tract. Like all endocrine hormones, GIP is transported by blood. 2. GIP is also thought to have significant effects on fatty acid metabolism through stimulation of lipoprotein lipase activity in adipocytes. 3. Gastric inhibitory polypeptide receptors are seven-transmembrane proteins found on beta cells in the pancreas. 4. It has been found that type 2 diabetics is not responsive to GIP.

GI Hormones Hormone Source Stimuli for Release Action(s)

Gastrin Cholecystokinin Secretin Gastric inhibitory peptide G cells, which are located in gastric pits, primarily in the antrum region of the stomach Mucosal epithelial cells in the duodenum Mucosa] epithelial cells in the duodenum Mucosal epithelial cells in the duodenum Presence of certain foodstuffs, especially peptides, certain amino acids, and calcium in the gastric lumen Presence of fatty acids and amino acids in the small intestine Acidification of the duodenum Presence of fat and glucose in the small intestine Stimulates gastric acid secretion Stomach motility Principal stimulus for the delivery of pancreatic enzymes and bile into the small intestine Principal stimulus for the pancreas to secrete a bicarbonate-rich fluid, which neutralizes the acid Inhibits gastric secretion and motility Enhances the release of insulin in response to infusions of glucose

Which of the following hormones' secretion is stimulated by stomach distention? • Gastrin • Cholecystokinin (CCK) • Secretin • Gastric inhibitory peptide (GIP) • All of the above

Gastrin Gastrin is a major physiological regulator of gastric acid secretion. Gastrin also has an im¬portant trophic or growth-promoting influence on the gastric mucosa. Gastrin is synthe¬sized in G cells, which are located in gastric pits, primarily in the antrum region of the stomach, and binds receptors found predominantly on parietal and enterochromaffin-like 1. The five C-terminal amino acids of gastrin and cholecystokinin are identi¬;Notes cal, which explains their overlapping biological effects. 2. Excessive secretion of gastrin, or hypergastrinemia, is a well-recognized cause of a severe disease known as Zollinger-Ellison syndrome.

Which of the following is not secreted from the duodenal segment of the small intestine? • Cholecystokinin • Gastric inhibitory peptide • Gastrin • Secretin

Gastrin The following are secreted from the duodenal segment of the small intestine: • Secretin: the small intestine is periodically assaulted by a flood of acid from the stomach, and it is important to put out that fire in a hurry to avoid acid bums. Secretin functions as a type of firefighter: secretin is released in response to acid in the small intestine, and stimulates the pancreas to release a flood of bicarbonate base, which neutralizes the acid. Secretin has the following functions: • Inhibits stomach motility and gastric acid secretion. • Stimulates the pancreatic duct cells to secrete a fluid that contains a lot of bicar-bonate ions but is low in enzymes. • Stimulates the secretion of bile from the gallbladder. • Cholecystokinin plays a key role in facilitating digestion within the small intestine. Cholecystokinin is secreted from mucosal epithelial cells in the first segment of the small intestine (duodenum), and stimulates delivery into the small intestine of digestive enzymes (trypsin, chymotrypsin, and carboxypeptidase) from the pancreas and bile from the gallbladder. Cholecystokinin is also produced by neurons in the enteric nerv¬ous system, and is widely and abundantly distributed in the brain. • Gastric inhibitory peptide (GIP) is a member of the secretin family of hormones. GIP was discovered as a factor in extracts of intestine that inhibited gastric motil- ity and secretion of acid, and initially called enterogastrone. Like secretin, GIP is secreted from mucosal epithelial cells in the first part of the small intestine. Gastrin is a major physiological regulator of gastric acid secretion. Gastrin also has an important trophic or growth-promoting influence on the gastric mucosa. Gastrin is syn¬thesized in G cells, which are located in gastric pits, primarily in the antrum region of the stomach and binds receptors found predominantly on parietal and enterochromaffin-like cells.

Pancreatic Endocrine Hormones Hormone Purpose Action Secreted in Response to Secretion Inhibited by Disease Due to Deficient Action Disease Due to Excess Action

Glucagon Insulin Somatostatin Gastrin Vasoactive intestinal polypeptide Assist insulin in regulating blood glucose in the normal range Regulate blood glucose in the normal range Regulate the production and excretion of other endocrine hormones Assist in digestion within the stomach Help control water secretion and absorption from the intestines Forces many cells to release glucose Forces many cells to absorb and use glucose Slows down production of insulin, glucagon, gastrin, and other endocrine hormones Induce acid-producing cells of the stomach to produce acid Causes intestinal cells to secrete water and salts into the intestine Low blood glucose High blood glucose High levels of other endocrine hormones Food in the stomach and intestines Unclear High blood glucose Low blood glucose Low levels of other endocrine hormones Absence of food in stomach and intestines Unclear Hypoglycemia Diabetes Poorly defined Poorly defined No symptoms Hyperglycemia Hypoglycemia Diabetes Stomach ulcers Severe watery diarrhea and salt imbalance

In a cotton-candy-eating competition, you consume 14 moderately sized and overpriced bags of threaded sugar. This causes your portal vein to drop tremendous loads of glucose to your hepatocytes soon after. Which of the following enzymes functions only when this happens? N • Pyruvate kinase • Glucokinase • Phosphofructokinase • Hexokinase

Glucokinase Glucokinase is the name given to a special liver form of the enzyme hexokinase. Like hexokinase, glucokinase catalyzes the ATP-dependent phosphorylation of glucose to form glucose-6-phosphate (G6P) and ADP. This is the first step of glycolysis. The enzyme will act on a variety of 6-carbon sugars, producing moieties phosphorylated at position six. Glucokinase, however, has a higher K. for sugar substrate compared to hexokinase (10 mM vs.1 mM). This difference is very important for the liver, which is a major source of glucose from gluconeogenesis. By phosphorylating glucose, glucokinase creates glucose-6-phosphate. Glucose-6-phosphate can then be used by the liver through the glycolytic pathway. Along with this process in the liver, glucokinase also facilitates glycogen synthesis. Through this, the majority of the body's glucose is stored. Glucose-6-phosphate is also one of the starting materials of the TCA cycle, which is responsible for the majority of ATP production in the body. 1. Glucokinase is not involved in the process of gluconeogenesis. Instead, the enzyme glucose-6-phosphatase catalyzes the hydrolysis of glucose-6¬phosphate to glucose and phosphate. 2. Glucokinase is also the predominant enzyme for the phosphorylation of glucose in beta cells of the pancreas. 3. Other tissues use hexokinase to do the same thing as glucokinase. 4. Hexokinase, phosphofructokinase and pyruvate kinase are the three regulatory enzymes of glycolysis.

Which of the following does not increase as a result of the action of growth hormone? • Amino acid uptake • Protein synthesis • Glycogenolysis • Gluconeogenesis

Gluconeogenesis Growth hormone, also known as somatotropin, is a protein hormone of about 190 amino acids that is synthesized and secreted by cells called somatotrophs in the anterior pituitary. Growth hormone is a major participant in control of several complex physiologic processes, including growth and metabolism. Growth hormone (GH), in contrast to other hormones, does not function through a target gland but instead exerts effects on all or almost all tissues of the body. GH is produced by the acidophils in the pars distalis of the anterior pituitary gland. GH causes the liver (and to a much lesser extent other tissues) to form several small proteins called somatomedins (also called insulin-like growth factors) that in turn have the potent effect of increasing all aspects of bone growth. Basic metabolic effects of growth hormone: • Increased rate of protein synthesis in all cells of the body. • Decreased rate of carbohydrate utilization throughout the body. • Increased mobilization of fats and the use of fat for energy. *** Growth hormone causes cells to shift from using carbohydrates to using fat for energy. 1. Secretion of GH is increased by sleep, stress, starvation, exercise, and Notes I hypoglycemia. 2. Secretion of GH is decreased by somatostatin, somatomedins (negative feedback control), obesity, hyperglycemia, and pregnancy.

Summary of Vitamin K Dietary Sources Major Body Functions Deficiency

Green and yellow vegetables, small amount in cereals, fruits, and meats Required for synthesis of prothrombin and certain other clotting factors in the liver • Retarded blood clotting • Excessive bleeding

Hormones of the Hypothalamus Hormone Source Target Action(s)

Growth hormone- releasing hormone (GRH) Growth hormone- inhibiting hormone (GM) Corticotropin- releasing hormone (CRH) Thyrotropin- releasing hormone (TRH) Gonadotropin- releasing hormone (GNRH) Prolactin- releasing hormone (PRH) Prolactin- inhibiting hormone (P/H) Hypothalamus Hypothalamus Hypothalamus Hypothalamus Hypothalamus Hypothalamus Hypothalamus Adenohypophysis (somatotrophs) Adenohypophysis (somatotrophs) Adenohypophysis (corticotrophs) Adenohypophysis (thyrotrophs) Adenohypophysis (gonadotrophs) Adenohypophysis (corticotrophs) Adenohypophysis (corticotrophs) Stimulates secretion of growth hormone Inhibits secretion of growth hormone Stimulates secretion of adrenocorticotrophic hormone (ACTH) Stimulates secretion of thyroid-stimulating hormone (TSH) and prolactin Stimulates release of FSH and LH Stimulates secretion of prolactin Inhibits secretion of prolactin

Which one of the following sequences places the lipoproteins in the order of most dense to least dense? • HDL / VLDL / chylomicrons / LDL • LDL / chylomicrons / HDL / VLDL • HDL / LDL / VLDL / chylomicrons • VLDL / chylomicrons / LDL / HDL • Chylomicrons / HDL / LDL / VLDL Which of these lipoproteins is the primary plasma carrier of cholesterol?

HDL / LDL / VLDL / chylomicrons LDL Lipids (triglycerides and cholesterol) are not able to move in body fluids due to lipids, hydrophobic nature so they are packaged in micellar structures called lipoproteins. The various lipoproteins are classified in terms of density. Note: Since lipids are much less dense than proteins, there is an inverse relationship between the lipid content and density (i.e., high lipid content means low density particle). The major components of lipoproteins are triacylglycerols (triglycerides), cholesterol, and cholesterol esters, which are the components being transported, and phospholipids and proteins which make up the micellar membrane (the protein component alone is called an apolipoprotein). Types of lipoproteins: • Chylomicrons: least dense lipoprotein: most triglyceride and the least protein content. Transport primarily dietary triacylglycerols around the body. • VLDLs (very low-density lipoproteins): more dense than chylomicrons; high content of triglycerides. Transport endogenous triacylglycerols to various tissues (primarily muscle and adipose tissue). • LDLs (low-density lipoproteins): denser than VLDLs; less triglyceride and more protein content. Has highest content of cholesterol. They are the primary plasma carriers of cholesterol for delivery to all tissues. • HDLs (high-density lipoproteins): most dense lipoprotein; has the lowest triglyceride and highest protein content. Transfers cholesterol as an acyl ester derivative from other tissues back to the liver. Note: These lipoproteins are transported into the cells by way of receptor-mediat¬ed endocytosis.

The major regulatory enzyme of cholesterol synthesis is: • Thiolase • HMG-CoA reductase • HMG-CoA synthase • HMG-CoA kinase

HMG-CoA reductase Although cholesterol is synthesized in most tissues of the body, where cholesterol serves as a component of cell membranes, it is produced mainly in the liver. Cholesterol is synthesized from acetyl-CoA; key intermediates in cholesterol biosyn¬thesis are HMG-CoA, mevalonic acid, isopentenyl pyrophosphate, and squalene. In the liver, bile salts are formed from cholesterol; in certain endocrine tissues, cholesterol is converted to steroid hormones -- testosterone, cortisol, progesterone, and estradiol, which is the most potent naturally occurring human estrogen; vitamin D is also formed from cholesterol by a series of reactions requiring the skin, liver, and kidney. 1. Cholesterol absorption depends upon the presence of bile salts in the Notes intestinal lumen. 2. Cholesterol is mostly esterified with fatty acids when circulating in blood plasma. 3. Circulating cholesterol is taken up into liver cells where it inhibits synth¬esis of additional cholesterol from acetyl-CoA via allosteric inhibition of HMG-CoA reductase. *** This provides an intrinsic feedback control system to reduce excess cholesterol synthesis. 4. Thiolase and HMG-CoA synthase are both involved in the synthesis of cholesterol. The reactions these enzymes catalyze are reversible and do not commit the cell to the synthesis of cholesterol.

Isotopes of an element: • Have different chemical properties but the same weights • Have the same chemical properties but different weights • Have different chemical properties and weights • Have the same chemical properties and weights

Have the same chemical properties but different weights Atoms of the same element can have different numbers of neutrons; the different possible versions of each element are called isotopes. For example, the most common isotope of hydrogen (protium) has no neutrons at all; there's also a hydrogen isotope called deuterium, with one neutron, and another, tritium, with two neutrons. Isotopes are stable or radioactive forms of an element that differ in atomic weight but are otherwise chemically identical to the naturally abundant form of the element. Isotopes of a given element have the same number of protons but differ in the number of neutrons. Important point: Isotopes have the same atomic number but different mass numbers. Remember: The atomic number is the number of protons, and the mass number is the sum of protons and neutrons. Note: The radioactive forms of isotopes are often used as tracers in medical radiography.

Which of the following hormones are/is secreted by the placenta? • Testosterone • Progesterone • Estrogen • Human chorionic gonadotropin (hCG) • All of the above

Human chorionic gonadotropin (hCG) *** Human chorionic gonadotropin (hCG) is produced by the placenta and stim¬ulates the corpus luteum to produce estradiol and progesterone. The ovaries of a female produce ova, the female sex hormones (progesterone and estrogen), and follicles. The corpus luteum is a yellowish mass of cells that forms from an ovarian follicle after the release of a mature egg (ovulation). If the mature egg is not fertilized and pregnancy does not occur, the corpus luteum retrogresses to a mass of scar tissue (corpus albicans) which eventually disappears. If the mature egg is fertilized and pregnancy does occur, the corpus luteum does not degenerate but persists for several months.

A patient comes into your office breathing hard after running across the street to get to his appointment on time. Which of the following would best describe this patient? • Hypocapnea • Dyspnea • Hypercapnea • Hyperapnea

Hypercapnea Note: Hyperventilation results in the loss of carbon dioxide (CO2) from the blood (hypocapnia), thereby causing a decrease in blood pressure and sometimes fainting. Hypoventilation results in an increased level of carbon dioxide (CO2) in the blood (hypercapnia).

Cortisol (hydrocortisone) has a direct inhibitory effect on which two structures? • Adrenal cortex • Hypothalamus • Anterior pituitary gland • Posterior pituitary gland

Hypothalamus Anterior pituitary gland The release of cortisol is controlled primarily by ACTH, which is secreted by basophils in the pars distalis of the anterior pituitary gland. The release of ACTH, in turn, is influenced by corticotropin-releasing hormone (CRH) from the hypothalamus. Cortisol exerts an inhibitory influence on both ACTH and CRH release by way of negative feedback. Feedback circuits are at the root of most control mechanisms in physiology, and are particularly prominent in the endocrine system. Instances of positive feedback certainly occur, but negative feedback is much more common. Negative feedback is seen when the output of a pathway inhibits input to the pathway. The heating system in your home is a simple negative feedback circuit. When the furnace produces enough heat to elevate the temperature above the set point of the thermostat, the thermostat is triggered and shuts off the furnace (heat is feeding back negatively on the source of heat). When the temperature drops back below the set point, negative feedback is gone, and the furnace comes back on. Cortisol is the main glucocorticoid produced and secreted by the cells of the zona fasciculata in the adrenal cortex. Cortisol allows glucagon and epinephrine to work more effectively at their target tissues, but antagonizes the actions of insulin. Glucocorticoids have anti-inflammatory effects, suppress the immune system, and influence metabolism by causing the movement of fuels from peripheral tissues to the liver, where gluconeogenesis and glycogen synthesis are stimulated. Important: A patient taking cortisol for a long period of time may experience atrophy of the adrenal cortex due to inhibition of ACTH production.

Releasing hormones are synthesized in the: ) • Posterior pituitary • Hypothalamus • Anterior pituitary • Ovary

Hypothalamus The secretions of the anterior pituitary are controlled by hormones called hypothalamic releasing and inhibitory factors, which are secreted within the hypothalamus itself and then conducted to the anterior pituitary through minute blood vessels called the hypothalamic¬hypophyseal portal system. The hormones of the posterior pituitary (ADH and oxytocin) are synthesized in certain hypothalamic nuclei (supraoptic and paraventricular) of the brain, which contain the cell bodies of neurosecretory cells. These hormones are then transported along the axons of the neurosecretory cells to the pars nervosa (posterior pituitary). Neural inputs to the brain influence the hormones' release.

Components of the Electron Transport System Complex Protein Components

I (NADH dehydrogenase complex) II (Succinate dehydrogenase complex) HI (Ubiquinone-cytochrome c oxidoreductase complex) IV (Cytochrome oxidase complex) NADH dehydrogenase Succinate dehydrogenase Ubiquinone-cytochrome c oxidoreductase Cytochrome a and a3

Which of the following solutions has an osmotic pressure different from the other two solutions? • 1 M glucose • 1 M sodium chloride • 1 M potassium nitrate • They all have the same osmotic pressure

I M glucose *** The key to this question is the fact that osmotic pressure of a solution depends on the number of solute particles present and not on their various properties. Sodium chloride and potassium chloride will ionize into two ions per molecule, whereas glucose will remain a single molecule in solution. • Osmosis is the net diffusion of water through a semipermeable membrane caused by a concentration difference. • Osmotic pressure is the pressure that develops in a solution as a result of net osmosis into that solution; osmotic pressure is affected by the number of dissolved particles per unit volume of fluid. Note: Intracellular (fluid within cells) and extracellular (interstitial fluid and plasma) fluids have similar total osmotic pressures. Osmolarity is expressed in units of osmoles per liter of solution (osmol/L), while osmo¬lality is defined as osmoles per kilogram solvent (osmol/kg). While similar, osmolarity and tonicity are not the same. The key difference between the two that osmolarity is a measure of all solutes in solution, whereas tonicity is a measure of impermeable solutes. Osmolarity compares the amount of solutes in two solutions, whereas tonicity compares the osmotic pressure gradient. If a solution in compartment A is hypertonic to a solution in compartment B, water will flow from compartment B to compartment A in an effort to dilute the solutes in compartment A. This allows the two compartments to have equal solute concentration.

A patient of yours suffers from phenylketonuria (PKU). Your dental assistant offers her a bottle of soda. The patient, a relatively intelligent dental student, responds by saying: I • I cannot have this because it contains tyrosine, which I am unable to metabolize • I cannot have this because it contains phenylalanine, which I am unable to metabolize • Thank you, I need to drink this to supplement my phenylalanine levels • Thank you, I need to drink this to supplement my tyrosine levels Which supplement would you expect this patient to be taking? • Tyrosine • Phenylalanine • Both tyrosine and phenylalanine • Neither, no supplement needed

I cannot have this because it contains phenylalanine, which I am unable to me¬tabolize Tyrosine --- she cannot produce this amino acid Tyrosine is formed from phenylalanine, which is an essential amino acid that is needed for optimal growth in infants and for nitrogen equilibrium in adults. Hydrophobic amino acids have side chains that contain: • Aliphatic groups: valine, leucine, and isoleucine • Aromatic groups: phenylalanine, tyrosine, and tryptophan Dopamine, the thyroid hormones (triiodothyronine and thyroxine), melanin, norepinephrine, and epinephrine are all synthesized from the amino acid tyrosine. Remember: Melanin is the natural substance that gives color (pigment) to hair, skin, and the iris of the eye. 5-hydroxytryptamine (serotonin), melatonin, niacin and the nicotinamide moiety of NAD and NADP are formed from the essential amino acid tryptophan. 1. When the enzyme (phenylalanine hydroxylase) that catalyzes the trans¬formation of phenylalanine to tyrosine is not active because of a hereditary defect, the serious disease known as phenylketonuria (PKU) results. 2. Negative nitrogen balance (nitrogen output exceeds intake) may be caused by a dietary lack of essential amino acids. 3. Albinism is a genetic disease that results from errors in the synthesis of melanin from tyrosine in melanocytes. Albinos do not have problems with epinephrine synthesis, despite melanin and epinephrine having DOPA as a common intermediate, because a different enzyme is used in melanocytes for DOPA synthesis.

Prolactin is said to be under "predominant inhibitory control." Which of the following explains why? • In normal conditions, prolactin is constantly synthesized in the anterior pituitary. Only when prolactin is not needed does the inhibitory mechanism kick in. • In normal conditions, prolactin inhibitory factor is produced by the hypothalamus. Only when prolactin is needed does the hypothalamus stop synthesis and secretion. • In normal conditions, prolactin is synthesized by the hypothalamus. However, prolactin inhibitory hormone prevents the secretion unless prolactin is needed. • In normal conditions, prolactin inhibitory factor is produced by the anterior pituitary. Only when prolactin is needed does this stop and the ovaries are able to produce prolactin.

In normal conditions, prolactin inhibitory factor is produced by the hypothalamus. Only when prolactin is needed does the hypothalamus stop synthesis and secretion Prolactin is a single-chain protein hormone closely related to growth hormone. Prolactin is secreted by so-called lactotrophs in the anterior pituitary. Prolactin is also synthesized and se¬creted by a broad range of other cells in the body, most prominently various immune cells, the brain, and the decidua of the pregnant uterus. Prolactin stimulates milk production in the breast, stimulates breast development, inhibits ovulation (by decreasing synthesis and release of gonadotropin-releasing hormone), and inhibits spermatogenesis (by decreasing GnGH). The hypothalamus synthesizes a prolactin inhibitory factor (dopamine). Under normal conditions, large amounts of dopamine are continually transmitted to the anterior pituitary gland so that the normal rate of prolactin secretion is slight. Important: This is why prolactin is said to be under predominant inhibitory control by the hypothalamus. However, during pregnancy and lactation, the formation of dopamine itself is suppressed, thereby allowing the anterior pituitary gland to secrete an elevated amount of prolactin. Factors that increase prolactin secretion: • Estrogen (pregnancy), breast-feeding, sleep, stress, thyrotropin-releasing hormone (TRH), and dopamine antagonists Factors that decrease prolactin secretion: • Dopamine, bromocriptine (dopamine agonist), somatostatin, and prolactin (by nega-tive feedback). ***Dopamine serves as the major prolactin-inhibiting factor or "brake" on prolactin secretion. In contrast to what is seen with all the other pituitary hormones, the hypothalamus tonically suppresses prolactin secretion from the pituitary. In other words, there is usually a hypothal¬amic "brake" set on the lactotroph, and prolactin is secreted only when the brake is released. If the pituitary stalk is cut, prolactin secretion increases, while secretion of all the other pitu¬itary hormones fall dramatically due to loss of hypothalamic releasing hormones.

The primary disturbance in respiratory acidosis is: • Decreased arterial Pco2 • Increased arterial Pco2 • Increased arterial bicarbonate • Decreased arterial bicarbonate

Increased arterial Pco2 Respiratory acidosis is a clinical disturbance that is due to alveolar hypoventilation. Production of carbon dioxide occurs rapidly, and failure of ventilation promptly increases the Pco2. Alveolar hypoventilation leads to an increased Pco2 (i.e., hypercapnia). The increase in Pco2 in turn decreases the HCO3-/Pco2 and decreases pH. Hypercapnia and respiratory acidosis occur when impairment in ventilation occurs and the removal of CO2 by the lungs is less than the production of CO2 in the tissues.

CA patient of yours fails to tell you about his or her allergy to latex. You walk into the room and begin treatment. The allergic reaction presenting causes histamine release. All of the following are responses to this EXCEPT one. Which one is the EXCEPTION? • Vasodilation (particularly the arterioles) • Secretion of HCL • Bronchoconstriction • Increased blood pressure • Increased vascular permeability (particularly in capillaries and venules)

Increased blood pressure *** This is false; histamine causes decreased blood pressure. Histamine is a chemical messenger that mediates a wide range of cellular responses. Histamine is a powerful vasodilator that is formed by the decarboxylation of histidine (an amino acid). Histamine is found in all tissues, particularly in mast cells and their related blood basophils, with the highest concentration in the lungs. Histamine is an important protein involved in many allergic reactions. Allergies are caused by an immune response to a normally innocuous substance (i.e., pollen, dust) that comes in contact with lymphocytes specific for that substance, or antigen. In many cases, the lymphocyte triggered to respond is a mast cell. For this response to occur, a free-floating IgE (an immunoglobulin associated with allergic response) molecule specific to the antigen must first be attached to cell surface receptors on mast cells. Antigen binding to the mast cell-attached IgE then triggers the mast cell to respond or become activated. (Note: Degranulation describes the action of the mast cell when it is activated.) This response often includes the release of histamine. This increases the local blood flow and increases the permeability of the capillaries and venules, allowing large quantities of fluid and protein to leak into the tissues -- the characteristic "wheal." Histamine has powerful pharmacologic actions, which are mediated by two specific receptor types: 1. Ill receptors mediate the typical allergic and anaphylactic responses to histamine bronchoconstriction, vasodilation, and increased capillary permeability. 2. 112 receptors mediate other responses to histamine, such as the increased secretion of gastric acid and pepsin. Important: The actions of bradykinin (a vasodilating kinin) are similar to histamine. Bradykinin increases vascular permeability, dilates blood vessels, and causes the tissue swelling associated with inflammation.

Oral contraceptives work by: • Inhibiting follicle formation by eliminating the LH surge • Inhibiting ovulation by eliminating the LH surge • Inhibiting follicle formation by eliminating the FSH surge • Inhibiting ovulation by eliminating the FSH surge

Inhibiting ovulation by eliminating the LH surge Oral contraceptives ("the pill') are pills consisting of one or more female sex hormones taken by women to prevent pregnancy. Most oral contraceptives are combined pills that contain synthetic estrogen-like (ethynyl estradiol and mestranol) and progesterone-like (norethindrone, norgestrel) substances. These synthetic hormones apparently prevent the rise in luteinizing hormone. This, in turn, prevents ovulation. The exact mechanism is thought to be as follows: In the presence of either estrogen or progesterone (or a synthetic substitute), the hypothalamus fails to secrete the normal surge of LH-releasing factor (also called gonadotropin-releasing factor). This then inhibits the release of luteinizing hormone from basophils of the anterior pituitary gland. Subsequently, ovulation does not occur. 1. Ovulation occurs as a result of the estrogen-induced LH surge. Notes 2. Unlike other steroid hormones, all estrogens have an aromatic A ring.

Hormones That Affect Metabolism Hormones Metabolic Effects

Insulin Glucagon and epinephrine Thyroxine Growth hormone Cortisol Testosterone Promotes: Glucose uptake into cells Amino acid uptake into cells Glycogenesis, lipogenesis Inhibits: Lipolysis, protein synthesis Promotes: Glycogenesis, gluconeogenesis, protein synthesis Promotes: Glycogenolysis, gluconeogenesis, lipolysis Promotes: Amino acid uptake into cells, protein synthesis, glycogenolysis, lipolysis Promotes: Gluconeogenesis, lipolysis, breakdown of protein Promotes: Protein synthesis

During inspiration, there is a fall in: • Atmospheric pressure • Intraalveolar pressure • Intrapleural pressure • Intraalveolar and intrapleural pressure

Intraalveolar and intrapleural pressure Air flows because of pressure differences between the atmosphere and the gases inside the lungs. Air, like other gases, flows from a region with higher pressure to a region with lower pressure. Muscular breathing movements and recoil of elastic tissues create the changes in pressure that result in ventilation. Pulmonary ventilation involves three different pressures: • Atmospheric pressure is the pressure of the air outside the body • Intraalveolar (intrapulmonary) pressure is the pressure inside the alveoli of the lungs • Intrapleural pressure is the pressure within the pleural cavity Note: In the resting position, the intrapleural pressure is approximately 4 mmHg less than the atmospheric pressure. Hence, the intrapleural pressure is approximately 756 mmHg.*** It is subatmospheric, or negative. Inspiration (inhalation) is the process of taking air into the lungs. This is the active phase of ventilation because it is the result of muscle contraction. During inspiration, the diaphragm contracts, and the thoracic cavity increases in volume. This decreases the intraalveolar pressure so that air flows into the lungs. Important point: There is a fall in both intrapleural pressure and intraalveolar pressure. Expiration (exhalation) is the process of letting air out of the lungs during the breathing cycle. During expiration, the relaxation of the diaphragm and elastic recoil of tissue decreases the thoracic volume and increases the intraalveolar pressure. Expiration pushes air out of the lungs. Important point: Intrapleural pressure becomes less negative and intraalveolar pressure rises. 1. Following a normal expiration (functional residual capacity, FRC), the alveo¬lar pressure is 760 mmHg, which is the atmospheric pressure. 2. At functional residual capacity, the expanding forces are equal and opposite to the collapsing pressures. This is the point of rest. Either increasing or decreas¬ing volume from FRC requires muscle contraction.

Which of the following is not true involving aldosterone? • Causes Na retention • Causes K excretion • Renin controls it • Acts at the distal tubule • Is produced in the kidney

Is produced in the kidney *** This is false; aldosterone is produced in the adrenal cortex. Aldosterone is the principal mineralocorticoid and is secreted by cells located in the zona glomerulosa of the adrenal cortex. Aldosterone promotes reabsorption of sodium into the blood from the glomerular filtrate. Potassium is lost in the urine. Note: Increased blood aldosterone levels will result in high plasma volume and low potassium levels in the plasma. The major target of aldosterone is the distal tubule of the kidney, where aldosterone stimulates exchange of sodium and potassium. Three primary physiologic effects result: • Increased resorption of sodium: sodium loss in urine is decreased under aldosterone stimulation. • Increased resorption of water, with consequent expansion of extracellular fluid volume. This is an osmotic effect directly related to increased resorption of sodium. • Increased renal excretion of potassium. The two most significant regulators of aldosterone secretion are: 1. Concentrations of potassium ion in extracellular fluid• Small increases in blood levels of potassium strongly stimulate aldosterone secretion. 2. Angiotensin II: Activation of the renin-angiotensin system as a result of decreased renal blood flow (usually due to decreased vascular volume) results in release of angiotensin II, which stimulates aldosterone secretion. Important: Decreased sodium concentration causes the juxtaglomerular cells of the kidneys to secrete renin, which converts angiotensinogen to angiotensin I. Angiotensin I is converted to angiotensin II, which, in turn, stimulates the adrenal cortex to release aldosterone. Note: Addison's disease is caused by the hyposecretion of aldosterone and cortisol.

The isoelectric point (p1) • Is the pH at which the number of positive and negative charges on a molecule equal each other • Is the pH at which the number of positive and negative charges in a solution equal each other • Can be determined using the Henderson-Hasselbalch equation • Is the pKa of a solution at which it is neither basic nor acidic • Two of the above

Is the pH at which the number of positive and negative charges on a molecule equal each other Another way of stating it is -- the isoelectric point (also called the isoelectric pH) is the pH at which a solute has no net electric charge and thus does not move in an electric field. It is designated pI for that solute. This information has practical importance -- for a solution containing a mixture of amino acids, the different amino acids can be separated on the basis of the direction and relative rate of their migration when placed in an electric field at a known pH. The same applies to protein molecules and is frequently used to separate proteins. Example: The amino acid glycine has a net negative charge at any pH above glycine's pI and will thus move toward the positive electrode (the anode) when placed in an electric field. At any pH below glycine's pI, glycine has a net positive charge and will move toward the negative electrode (the cathode). The farther the pH of a glycine solution is from its isoelectric point (pI), the greater the net electric charge of the population of glycine molecules. Note: At physiologic pH, all amino acids have both a negatively charged carboxyl group (-COO) and a positively charged amino group (-NH3'). They are, therefore, dipolar ions (in this state, the compound is said to be a zwitterion).

All of the following statements concerning fluoride are true EXCEPT on-eN. Which one is the EXCEPTION? • It is excreted by the kidney • It passes the placental barrier • It hardens tooth enamel • It is deposited in calcified tissues

It hardens tooth enamel Fluoride does not make the enamel harder, but reduces the solubility of enamel due to the incorporation of fluoride into the apatite structure of the enamel. The concentration of fluoride in the body fluids is regulated by an equilibrium relationship between bone and urinary excretion. A deficiency of fluoride can lead to an increased incidence of dental caries, and toxicity leads to tooth enamel mottling and discoloration, increased bone density, and calcification. Facts about fluoride: • It is excreted by the kidney. • It is deposited in calcified tissues (i.e., skeletal). • It passes the placental barrier slowly. • At 1 ppm, fluoride is tasteless, colorless, and odorless. One ppm is the equivalent of 1 mg/L, or 1 inch in 16 miles. • It converts hydroxyapatite to fluoroapatite by the substitution of the OH ion with the fluoride ion. • Fluoridation of community water has been credited with reducing tooth decay by 50%-60% in the United States since World War II. More recent estimates of this effect show decay reduction at 18%-40%, which reflects that even in communities that are not optimally fluoridated, people are receiving some benefits from other sources (e.g., bottled beverages, toothpaste). • Fluoride works by stopping or even reversing the tooth decay process. Fluoride keeps the tooth enamel strong and solid by preventing the loss of (and enhancing the reattachment of) important minerals from the tooth enamel. • Water fluoridation costs, on average, 72 cents per person per year in U.S. commun-ities. • Children under age 6 years may develop enamel fluorosis if they ingest more fluoride than needed. A common source of extra fluoride is unsupervised use of toothpaste in very young children.

All of the following statements concerning enamel hypoplaasia are true EXCEPT one. Which one is the EXCEPTION? • It is a defect in the mineralization of the formed enamel matrix • The enamel of primary and permanent teeth appear pitted • Radiographically, the enamel is either absent or very thin over tips of cusps and interproximal areas • It can be caused by nutritional deficiencies

It is a defect in the mineralization of the formed enamel matrix *** This is false; it is a defect in the formation of the enamel matrix. The enamel is hard in context but thin and deficient in amount. The etiology may be hereditary or environmental. Examples of environmental causes include a vitamin deficiency (A and D), inadequate calcium intake, fluorosis, congenital syphilis, high fever, injury, or trauma to the mouth. Hypoplasia results only if the assault occurs during the time the teeth are developing. Either dentition may be involved. The teeth appear pitted, yellow to dark brown in color, and have open contacts. Radiographically, the enamel appears to be absent or very thin, especially over the cusp tips and interproximally. 1. Enamel hypocalcification is a defect in the mineralization of the formed enamel matrix. 2. Tooth erosion in bulimic patients is due to the solubility of hydroxyapatite in acid.

All of the following characterize saliva EXCEPT one. Which one is the EXCEPTION? • High potassium and bicarbonate ion concentrations • Low sodium and chloride concentrations • It is hypertonic • Its production is inhibited by vagotomy

It is hypertonic *** This is false; saliva is hypotonic due to the fact that the salivary ductal cells reabsorb sodium and chloride in exchange for potassium and bicarbonate. Functions of Saliva: • Lubrication: for the mastication and swallowing of food • Protection: prevents dehydration of the oral mucosa • Oral hygiene: antimicrobial properties and washes away food particles • Digestion: starch digestion by a -amylase (not required) Composition of Saliva (97% to 99.5% water): • Ionic components - The principle ions contained in saliva include sodium, pot¬assium, chloride, and bicarbonate ions. • Organic components - The primary organic components of saliva are lingual lipase, mucopolysaccharides and proline-rich glycoproteins. Also present are small amounts of immunoglobulin A (which is the only immunoglobulin to appear in saliva) lysozyme, lactoferrin, albumin, urea, and glucose. Note: Saliva supplies calcium and phosphate, which are important for remineraliza¬tion of the enamel. Remember: Caries is modified by saliva. High flow-rate saliva is a very effective buffer. The balance between demineralization and remineralization can therefore be altered substantially by the rate of salivary flow. Flow is decreased by salivary gland pathology (as occurs in several connective tissue disease and which can follow radiotherapy and cancer chemotherapy), by many mood-altering drugs and some drugs used in other medical treatment, in dehydration and during sleep. Flow increases naturally during vigorous chewing. A maximum salivary flow rate of less than 0.7 mL/min. is associated with high caries risk.

What is the general structure shown below? Hint: They are found in proteins.

It is the general structure of the amino acids found in proteins 1. With the exception of the nature of the R group, this structure is common Notes to all the a-amino acids. The central or a-carbon is in the center. Attached to this is a hydrogen atom (H), a carboxyl group (COOH), an amino group (H3/0, and the R group. In all amino acids except glycine, the a-carbon atom has four different substituent groups (in glycine, the R group is a hydrogen atom). 2. Amino acids can lose their nitrogen-containing amino groups and be converted to a-keto acids (alpha-keto acids) that can ultimately enter the Krebs cycle -- for example, by way of pyruvic acid or the Krebs cycle component oxaloacetic acid, both of which are a-keto acids. An a-keto acid is similar to an amino acid, except that an a-keto acid has oxygen rather than an amino group bonded to its a-carbon. 3. When proteins are broken down and used for energy, most of this energy is derived from the oxidation of a-keto acids (i.e., pyruvate, oxaloacetate, and a¬ketoglutarate). These substances can then enter the Krebs cycle.

All of the following statements concerning heparin are true EXCEPT one. Which one is the EXCEPTION? • Unlike other glycosaminoglycans that are extracellular compounds, heparin is an intracellular component of mast cells that line arteries, especially in the liver, lungs, and skin • It serves as a powerful anticoagulant • It is used in the treatment of certain types of lung, blood vessel, and heart disorders, and during or after certain types of surgery (open heart or bypass surgeries) • Small quantities are produced by basophil cells of the blood • It is usually found in large quantities in the blood

It is usually found in large quantities in the blood *** This is false; its concentration in the blood is normally slight, so that only under limited physiological conditions does heparin have significant anticoagulant effects. Heparin (a protein) is contained in secretory vesicles or granules within mast cells and the basophil cells of the blood, which are functionally almost identical to the mast cells. Heparin occurs in greatest concentration in the tissues surrounding the capillaries of the lungs and the liver. 1. The administration of heparin will result in an increase in bleeding time Notes due to the activation of antithrombin, a major protease inhibitor, which . rapidly inhibits thrombin. Heparin is used in treating patients who have C--- suffered a coronary thrombosis. 2. Heparin prevents the activation of factor IX (Christmas factor) and interferes with thrombin action. 3. Heparin can also enhance the removal of lipoproteins from the blood by binding apolipoprotein E (protein found on some liposomes) and by activat¬ing lipoprotein lipase.

All of the following statements concerning the pentose phosphate pathway are true EXCEPT one. Which one is the EXCEPTION? • It produces carbon dioxide (CO2) • It can produce NADPH • It requires ATP for phosphorylation • It can produce five-carbon sugars (used for DNA and RNA) • It is controlled by inhibition of glucose-6-phosphate dehydrogenase by NADPH • It occurs in the cytosol of the cell

It requires ATP for phosphorylation ***This is false; ATP is not directly involved in the pentose phosphate pathway. In the irreversible oxidative reactions of the pathway, one carbon of glucose¬6-phosphate is released as carbon dioxide, NADPH is generated, and ribulose¬5-phosphate is produced. In the reversible nonoxidative reactions, pentose phosphates produced from ribulose-5-phosphate are converted to the glycolytic intermediates fructose-6-phosphate and glyceraldehyde-3-phosphate. The major role of this pathway is the production of NADPH for reductive biosynthetic reactions (e.g., fatty acid synthesis) and the production of essential pentoses, particularly D-ribose, used in the biosynthesis of nucleic acids. This pathway is prominent in tissues actively carrying out the biosynthesis of fatty acids and steroids from small precursors, particularly the mammary glands, adipose tissue, the adrenal cortex, and the liver. Large amounts of NADPH are required in the reductive synthesis of fatty acids from acetyl-CoA -- specifically the reduction of double bonds and carbonyl groups. Other tissues less active in synthesizing fatty acids, such as skeletal muscle, are virtually lacking in the pentose phosphate pathway. Glucose-6-phosphate dehydrogenase is the committed step of the pentose phosphate pathway. This enzyme is regulated by availability of the substrate NADP÷. Additional enzymes include ribulose-5-phosphate epimerase, ribulose-5-phosphate iso-merase, transketolase, and transaldolase. Note: It is also called the pentose shunt, the hexose monophosphate pathway, or the phosphogluconate pathway.

Acid-base Disorders Cause Primary Disturbance Compensation Metabolic acidosis Metabolic alkalosis Respiratory acidosis Respiratory alkalosis

Ketoacidosis Lactic acidosis Chronic renal failure Salicylate intoxication Vomiting Hyperaldosteronism Loop or thiazide diuretics Opiates Sedatives Anesthetics COPD Pneumonia; pulmonary embolus High altitude Psychogenic Salicylate intoxication Decreased [HCO3-] Increased [HC01] Increased Pco2 Decreased Pc02 Decreased Pco2 Increased Pco2 Increased [HCO3-] Decreased [HCO3]

All of the following are affected by epinephrine and/or norepinephrine_) C EXCEPT one. Which one is the EXCEPTION? } • Blood glucose • Total peripheral resistance • Heart rate • Kidney function

Kidney function The adrenal medulla is a specialized ganglion of the sympathetic nervous system. Preganglionic fibers synapse directly on chromaffin cells in the adrenal medulla. These cells secrete epinephrine (80%) and norepinephrine (20%) into the circulation. Both of these hormones are water-soluble, direct-acting adrenergic agonists and are biosynthesized from the amino acid tyrosine. Water-soluble hormones cannot pass through the plasma membrane and must have a plasma membrane receptor. Epinephrine (adrenalin) has the following effects: • Stimulates glycogenolysis and gluconeogenesis, which tend to raise blood glucose levels. Also stimulates lipolysis in adipose tissue (break-down of triglycerides into glycerol and fatty acids) • Increases the rate, force, and amplitude of the heartbeat • Constricts blood vessels in skin, mucous membranes, and kidneys • Dilates bronchioles in the lungs and relaxes bronchiolar smooth muscle • Activates muscle glycogen phosphorylase Norepinephrine (noradrenalin) has the following effects: • Increases the heart rate and the force of contraction of heart muscle • Promotes lipolysis in adipose tissue • Constricts blood vessels in almost all areas of the body, thus increasing total peripheral resistance

All amino acids found in proteins are of the: ) • D-configuration • L-configuration • F-configuration • C-configuration

L-configuration Stereoisomers (optical isomers, or enantiomers) are compounds that have the same composition and the same order of atomic connections, but different molecular arrangements. In all standard amino acids (except glycine), the a-carbon is asymmetric, bonded to four different substituent groups (a carboxyl group, an amino group, an R group, and a hydrogen atom). This carbon is called a chiral center. The four different substituent groups can occupy two different arrangements in space, which are non-super-imposable mirror images of each other. These two forms are called stereoisomers (optical isomers, or enantiomers). Note: All molecules with a chiral center are also optically active. The classification and naming of stereoisomers are based on the absolute configuration of the four substituents of the asymmetric carbon atom. The reference compound to which all other optically active compounds are compared is the smallest sugar to have an asymmetric carbon -- glyceraldehyde. The naming of configurations of both simple sugars and amino acids is based on the absolute configuration of glyceraldehyde, as established by x-ray diffraction analysis. Important: The stereoisomers of all chiral compounds having a configuration related to L-glyceraldehyde are designated L ("levorotatory'), and the stereoisomers related to D-glyceraldehyde are designated D ("dextrorotatory'). The right and left designations for glyceraldehyde refer to the manner in which the two forms rotate plane-polarized light. Note: D-amino acids are found in some antibiotics and in bacterial cell walls.

The fasciculi gracilis and cuneatus are the: • Largest ascending tracts of the spinal cord • Largest descending tracts of the spinal cord • Smallest ascending tracts of the spinal cord • Smallest descending tracts of the spinal cord

Largest ascending tracts of the spinal cord The white matter of the spinal cord contains tracts that travel up and down the cord. Many of these tracts travel to and from the brain to provide sensory input to the brain, or bring motor stimuli from the brain to control effectors. Ascending tracts, those that travel toward the brain are sensory; descending tracts are motor. For most, the name will indicate if it is a motor or sensory tract. Most sensory tracts' names begin with spino, indicating origin in the spinal cord, and their names end with the part of the brain where the tract leads. For example, the spinothalamic tract travels from the spinal cord to the thalamus. Tracts whose names begin with a part of the brain are motor. For example, the corticospinal tract begins with fibers leaving the cerebral cortex and travels down toward motor neurons in the cord. The origin refers to the location of cell bodies of neurons from which the axons of tract arise. The termination refers to the structure in which the axons of the tract terminate.

Major Descending Tracts of the Spinal Cord Name Function Location Origin Termination

Lateral corticospinal Anterior corticospinal Lateral reticulospinal Medial reticulospinal Rubrospinal Vestibulospinal Voluntary movement, contraction of individual or small groups of muscles, particularly those moving hands, fingers, feet, and toes of opposite side Same as lateral corticospinal except mainly muscles of same side Mainly facilatory influence on motor neurons to skeletal muscles Mainly inhibitory influence on motor neurons to skeletal muscles Coordination of body move- ment and posture Mediates the influences of the vestibular end organ and the cerebellum upon extensor muscle tone Lateral white columns Anterior white columns Lateral white columns Anterior white columns Lateral white columns Lateral white columns Motor areas or cerebral cortex opposite side from tract location in cord Motor cortex but on same side as location in cord Reticular formation, midbrain, pons, and medulla Reticular formation, medulla mainly Red nucleus (of midbrain) Lateral vestibular nucleus (4th ventricle) Lateral or anterior gray columns Lateral or anterior gray columns Lateral or anterior gray columns Lateral or anterior gray columns Lateral or anterior gray columns Lateral or anterior gray columns

Major Ascending Tracts of the Spinal Cord Name Function Location Origin Termination

Lateral spinothalamic Anterior spinothalamic Fasciculi gracilis and cuneatus Anterior and posterior spinocerebellar Pain, temperature, and crude touch; opposite side Crude touch and pressure Discriminating touch and pressure sensations Unconscious kinesthesia Lateral white columns Anterior white columns Posterior white columns Lateral white columns Posterior gray column; opposite side Posterior gray column; opposite side Spinal ganglia; same side Anterior or posterior gray column Thalamus Thalamus Medulla Cerebellum

All of the following are formed via the cyclooxygenase ...' --..-, pathway EXCEPT one. Which one is the EXCEPTION? _) • Prostaglandins • Prostacyclin • Leukotrienes • Thromboxanes

Leukotrienes The prostaglandins and a number of related substances (prostacyclin, thromboxanes, and leukotrienes) are chemical messengers. One of these messengers is present in almost every body tissue. They act primarily as local messengers that exert their effects in the tissues that synthesize prostaglandins. Note: Leukotrienes are potent bronchoconstrictors and cause airway wall edema, increasing mucus production. They also attract eosinophils into the tissues and amplify the inflammatory process. Arachidonic acid (an unsaturated fatty acid) is the major compound from which prostaglandins, prostacyclin, thromboxanes, and leukotrienes are derived. Arachidonic acid is a part of phospholipids in the plasma membranes of cells. Various compounds activate a plasma membrane enzyme called phospholipase A2, and this enzyme splits arachidonic acid from the membrane phospholipids. Different metabolic pathways utilize different enzymes that convert arachidonic acid into the different messengers: • To form prostaglandins, prostacyclin, or thromboxanes, the cyclooxygenase pathway utilizes the enzyme cyclooxygenase. • To form leukotrienes, the lipoxygenase pathway utilizes the enzyme lipoxygenase. Note: Many NSAIDs including aspirin, block the cyclooxygenase pathway. The benefit of this blockade comes from the ability to slow the synthesis of prostaglandins, thus reducing their inflammatory ability. Remember: Prostacyclin is a prostaglandin produced in the walls of blood vessels that acts as a vasodilator and inhibits platelet aggregation.

What is the name of the structure shown below? Hint: It is the basic structure of cell membranes.

Lipid bilayer In an aqueous environment (water), phospholipid molecules form lipid bilayers (also called bimolecular sheets), in which the polar regions (phosphate group that is negatively charged) are located at the surfaces of the bilayer, where the molecules interact with water (hydrophilic). The nonpolar regions (fatty acid portion) are hydrophobic, and orient themselves toward the interior of the bilayer so as to minimize contact with the aqueous portion. In this lipid bilayer, globular proteins (peripheral and integral) are embedded at irregular intervals, held by hydrophobic interactions between the membrane lipids and hydrophobic domains in the proteins. 1. Lipids, when suspended in water, spontaneously form bilayer structures Notes that are stabilized by hydrophobic interactions. 2. This lipid bilayer serves as a permeability barrier, yet it is quite fluid. The membrane mosaic is fluid because the interactions among lipids, and between lipids and proteins, are noncovalent, leaving individual lipid and protein molecules free to move laterally in the plane of the membrane. 3. Bilayers arise through the operation of two opposing forces: (1) attractive forces between hydrocarbon chains (van der Waals forces) caused by the hydrophobic effect forcing such chains together and (2) repulsive forces between the polar head groups.

The cell (plasma) membrane is a fluid mosaic of: • Lipids and carbohydrates • Proteins and carbohydrates • Lipids and proteins • Carbohydrates

Lipids and proteins The cell membrane (plasma membrane) is composed mainly of lipids and proteins. The lipids form a bilayer, with their hydrophilic head groups interacting with water on both the extracellular and intracellular surfaces, and lipids' hydrophobic fatty acyl chains in the central portion of the membrane. Peripheral proteins are embedded at the periphery; integral proteins span from one side of the membrane to the other side. 1. Carbohydrates are attached to proteins and lipids on the exterior side of Notes the cell membrane. 2. Integral proteins are associated with the hydrophobic phase of the bilayer. Important point: The membrane is said to be a "fluid-mosaic" since lipids and proteins can diffuse laterally within the plane of the membrane. However, peripheral proteins seldom flip from the outer to the inner membrane or vice versa. The lipids that make up the bulk of a cell's surface membrane fall into three classes: phospholipids, steroids (primarily cholesterol), and glycolipids (for example, gangliosides). About half of the molecules in an average membrane are phospholipids. Examples include: sphingomyelin, phosphatidyl choline (lecithin), and phosphatidyl ethanolamine (cephalin). Phospholipids are amphiphilic with the hydrocarbon tail of the molecule hydrophobic and its polar head hydrophilic. As the plasma membrane faces watery solutions on both sides, its phospholipids accommodate this by forming a phospholipid bilayer with the hydrophobic tails facing each other.

Summary of Biotin Dietary Sources Major Body Functions Deficiency

Liver, kidney, yeast, milk, egg yolk Essential for the activity of many enzyme systems that are involved in amino acid and protein synthesis Required for the carboxylation of acetyl CoA to malonyl CoA, an intermediate in fatty acid synthesis Fatigue Depression Nausea Dermatitis Muscular pains Loss of hair

Summary of Folic Acid (folate or folacin) Dietary Sources Major Body Functions Deficiency

Liver, kidney, yeast, mushrooms, green vegetables Involved in the synthesis of purines and thymine, which are required for DNA formation • Megaloblastic anemia • Diarrhea • Glossitis

Summary of Niacin Dietary Sources Major Body Functions Deficiency

Liver, meat, fish, grains, legumes, poultry, peanut butter Component of NAD' and NADP+, which are involved in glycolysis, the Krebs cycle, and other reactions Pellagra, which is characterized by diarrhea, dermatitis, dementia, the 3 D's

Which receptors below when stimulated initiate the Hering-Breuer reflex? • Irritant receptors • J receptors • Lung stretch receptors • Joint and muscle receptors

Lung stretch receptors These receptors are located in the smooth muscle of the airways. When these receptors are stimulated by distension of the lungs, the receptors initiate the Hering-Breuer reflex, which prevents the overinflation of the lungs. During inspiration, these stretch receptors increase their activity, and stimuli are sent over the afferent vagus nerve to the respiratory control centers in the brain (medulla). When the stimuli reach the critical level, inspiration ceases. Note: This reflex does not appear to be of great importance in the control of respiration during normal breathing. This reflex is mainly a protective mechanism that prevents the lungs from overfilling. Other Receptors for Control of Breathing: • J receptors -- are located in the alveolar walls; when stimulated these receptors cause rapid, shallow breathing • Irritant receptors -- are located between airway epithelial cells; are stimu¬lated by noxious substances (e.g., dust, pollen) • Joint and muscle receptors -- are activated during exercise to stimulate breathing Remember: Carbon dioxide concentration in the blood (Pco2) is the most important stimulus for the respiratory control center (medulla). An increased Pco2 increases respiration by stimulating the central chemoreceptors, while a decrease in Pco2 inhibits respiration.

{-Which of the following is the cause of the hyperpolarization that occurs f( a few milliseconds after the action potential is over? • Many sodium channels remain open for several milliseconds after repolarization of the membrane is complete • All potassium channels remain closed for several milliseconds after repolarization of the membrane is complete • Many potassium channels remain open for several milliseconds after repolarization of the membrane is complete • All sodium and potassium channels remain closed for several milliseconds after repolarization of the membrane is complete

Many potassium channels remain open for several milliseconds after repolarization of the membrane is complete The increased potassium conductance allows for additional potassium efflux, leaving the interior of the cell more negative. This opening of potassium channels, although delayed, is due to the initial depolarizing stimulus. Remember: After the action potential is over, for a few milliseconds the membrane potential becomes even more negative than the original resting membrane potential. This is called hyperpolarization. Gradually, the ion concentrations go back to resting levels, and the cell membrane returns to (-) 70 mV. The importance of the hyperpolarization is that the cell remains in a "hypoexcitable state," the relative refractory period. This means that, in order to trigger a second action potential, the depolarizing stimulus must be of a greater magnitude to achieve threshold. Important point to remember: During the absolute refractory period, the membrane will not respond to any stimulus. During the relative refractory period, however, a very strong stimulus may elicit a response in the membrane. 1. Presynaptic neurons transmit information toward a synapse; postsynap¬Notes tic neurons transmit information away from a synapse. 2. Nerve impulses travel in only one direction because of the fact that synapses are polarized. 3. Electrical synapses are rare in the CNS (common in cardiac and smooth muscle). They are connected by gap junctions, which allow local electrical currents resulting from action potentials in the presynaptic neuron to pass directly to the postsynaptic neuron.

Summary of Thiamin (Vitamin B1) Dietary Sources Major Body Functions Deficiency

Meat (especially pork or organ meats), grains, dry beans and peas, fish, poultry Involved in the metabolism of carbohydrates and many amino acids Adult beriberi is characterized by dry skin, irritability, disorderly thinking, and progressive paralysis

Which two amino acids have sulfur-containing side chains (R groups)? ) • Lysine • Cysteine • Arginine • Glutamate • Methionine

Methionine Cysteine Each of the 20 amino acids found in proteins can be distinguished by the R-group substitution on the a-carbon atom. There are two broad classes of amino acids based upon whether the R group is hydrophobic or hydrophilic. The hydrophobic (non-polar) amino acids tend to repel the aqueous environment and, therefore, reside predominantly in the interior of proteins. This class of amino acids does not ionize or participate in the formation of H-bonds. The hydrophilic (polar) amino acids tend to interact with the aqueous environment, are often involved in the formation of H-bonds, and are predominantly found on the exterior surfaces proteins or in the reactive centers of enzymes. The two broad classes of amino acids are further distinguished by those with: 1. Non-polar (hydrophobic), aliphatic R groups: includes alanine, valine, leuc¬ine, isoleucine, glycine, and proline. 2. Aromatic (generally non-polar) R groups: includes phenylalanine, tyrosine, and tryptophan. 3. Polar (hydrophilic), uncharged R groups: includes serine, threonine, cysteine, methionine, asparagine, and glutamine. Note: The polarity of cysteine and methionine is contributed by their sulfur atom, and that of asparagine and glutamine by their amide groups. 4. Negatively charged (acidic) R groups: includes aspartic acid and glutamic acid. 5. Positively charged (basic) R groups: includes lysine, arginine, and histidine.

Summary of Riboflavin (Vitamin B2) Dietary Sources Major Body Functions Deficiency

Milk, leafy vegetables, fresh meat, egg yolks Constituents of two flavin nucleotide coenzymes (FAD and FMN) that function with some enzymes (flavoproteins) that catalyze oxidation reduction reactions • Cracks at corner of the mouth (angular cheilitis) • Dermatitis • Glossitis (tongue appearing smooth and purplish)

The first heart sound corresponds to which two valves closing? • Pulmonary valve • Aortic valve • Mitral valve • Tricuspid valve

Mitral valve (bicuspid valve) Tricuspid valve (the atrioventricular valves) The first heart sound ("Lub') is associated with the closure of the atrioventricular valves (mitral and tricuspid valves) at the beginning of ventricular contraction. This sound is largely due to vibrations of the taut A-V valves immediately after closure and to the vibration of the walls of the heart and major vessels around the heart. 1. It is louder and longer than the second heart sound. 2. Ventricular systole starts with the first heart sound. 3. Ventricular diastole ends with the first heart sound. The second sound ("Dub') is associated with the closure of the semilunar valves (pulmonary and aortic valves) as the ventricles begin to relax following their contraction. This sound is due largely to vibrations of the taut, closed semilunar valves and to the vibration of the walls of the pulmonary artery, the aorta, and, to some extent, the ventricles. 1. Diastole begins with the second heart sound. Notes(2. The aortic valve closes before the pulmonary valve; this causes "splitting" of the second heart sound.

IgG IgA IgD IgM IgE

Most common antibody; important antibody of the secondary antibody response; passes the placenta and enters the fetal circulation. Second most abundant; occurs in body secretions and protects surface tissues; synthesized by the plasma cells in the mucous membranes of the GI, respiratory, and urinary tracts. Serves as the receptor site on the surface of the B lymphocytes; function is unknown or not fully understood. Large antibody consisting of five antibody units; important in the primary antibody response; first antibody to appear in the circulation after antigen stimulation; does not pass the placenta or enter the fetal circulation. Is present in only trace amounts in serum; reaginic activity resides in the immunoglobulin; protects external mucosal surfaces; tightly bound to its receptors on mast cells and basophils; responsible for type I hypersensitivity reactions (allergic and anaphylactic).

The liver releases glucose back into the circulating blood during exercise. Which two organs take up this extra glucose? • Kidneys • Muscle • Heart • Brain • Lungs

Muscle Brain Remember: Glucose is the major fuel for the brain; glucose oxidizes approximately 140 g/day to carbon dioxide and water, producing ATP. The brain contains no significant stores of glycogen, and is therefore completely dependent on the availability of blood glucose. The liver has the major responsibility for maintaining blood glucose levels. Glucose is required particularly by tissues such as the brain and red blood cells. Note: Red blood cells oxidize glucose to pyruvate and lactate. The liver releases glucose into the blood during muscular activity and in the interval between meals. The released glucose is derived from two sources: (1) The breakdown of stored glycogen (2) The formation of new glucose by the process of gluconeogenesis. 1. In skeletal muscle, the glucose is phosphorylated, and then degraded by glycolysis to pyruvate, which is converted to acetyl-CoA and oxidized via the citric acid cycle. 2. Glucose is the major end product of carbohydrate ingestion. 3. The presence of glucose in the urine proves a person has exceeded his or her renal threshold for glucose. 4. Fasting leads to decreased liver glycogen. 5. In addition to the liver, skeletal muscle is the other major site of glycogen storage.

Summary of Vitamin B12 Dietary Sources Major Body Functions Deficiency

Muscle and organ meats, eggs, dairy products, fish Required for two reactions in the body: 1. Involved in the formation of methionine 2. Involved in the conversion of methylmalonyl CoA to succinyl CoA Pernicious anemia, neurologic disorders, glossitis

Bile salts are detergent-like substances that are synthesized in the (?) from cholesterol, stored in the (?) and are secreted into the (?). They pass into the (?) the dietary lipids. • Kidney / liver / blood / stomach • Liver / kidney / blood / stomach • Liver / gallbladder / bile / intestine • Kidney / gallbladder / bile / intestine

liver / gallbladder / bile / intestine Like a detergent, bile salts contain hydrophobic and hydrophilic components. The hydrophobic portions of the molecule associate with the fat, and the hydrophilic parts associate with water, serving to solubilize (emulsify) the otherwise insoluble fat. The micelles, which are tiny microdroplets emulsified by bile salts, travel to the microvilli of the intestinal epithelial cells, which absorb the fatty acids. The bile salts are resorbed, recycled by the liver, and secreted into the gut during subsequent digestive cycles. Bile salts perform two important actions in the intestinal tract: 1. Most important, bile salts help in the absorption of fatty acids, monoglycerides, cho-lesterol, and other lipids from the intestinal tract (form water-soluble complexes, called micelles, with fatty acids and glycerides). 2. Bile salts also have a detergent action on the fat particles in the food, which decreases the surface tension of the particles and allows agitation in the intestinal tract to break the fat globules into minute sizes. Bile acids are usually conjugated in amide linkage with the amino acid glycine or taurine, giving bile salts. The cholic acid conjugates with glycine and taurine are called glycocholate and taurocholate, respectively.

All of the following statements are true EXCEPT one. Which one is the EXCEPTION? • Myoglobin has a higher affinity for 02 than hemoglobin • Hemoglobin has a higher affinity for CO2 than 02 • Hemoglobin is capable of binding more oxygen than myoglobin can • Myoglobin is dimeric while hemoglobin consists of four proteins • Myoglobin is found only in muscle cells

Myoglobin is dimeric while hemoglobin consists of four proteins Myoglobin and hemoglobin are heme proteins whose physiological importance is principally related to their ability to bind molecular oxygen. Myoglobin is a monomeric heme protein (it contains only one heme unit, not four like hemoglobin) found mainly in muscle tissue where myoglobin serves as an intracellular storage site for oxygen. During periods of oxygen deprivation, oxymyoglobin releases its bound oxygen, which is then used for metabolic purposes. It is also called muscle hemoglobin. Important point to remember: Hemoglobin contains four hemes and can potentially associate with four oxygen molecules. Myoglobin has a much greater affinity for oxygen than does hemoglobin. This makes myoglobin well suited for its biological function within muscle cells, which is to store oxygen and make myoglobin's available to the mitochondria. Myoglobin is, in fact, much better at this than hemoglobin because its very high affinity for oxygen at low Poe enables myoglobin to bind and store oxygen effectively. In summary, hemoglobin and myoglobin are specialized proteins, adapted for different kinds of oxygen-binding functions. Note: Carbon monoxide also binds coordinately to heme iron atoms in a manner similar to that of oxygen, but the binding of carbon monoxide to heme is much stronger than that of oxygen. The preferential binding of carbon monoxide to heme iron is largely responsible for the asphyxiation that results from carbon monoxide poisoning.

All of the following statements are true EXCEPT one. Which one is the EXCEPTION? J • Peripheral nerve fibers can sometimes regenerate if the soma (cell body) is not damaged and some of the neurilemma remains intact • The neurilemma forms a regeneration tube through which the growing axon re¬establishes its original connection • If the nerve originally led to a skeletal muscle, the muscle atrophies in the absence of innervation but regrows when the connection is re-established • Nerve fibers of the CNS (brain and spinal cord) possess the thickest neurilemma

Nerve fibers of the CNS (brain and spinal cord) possess the thickest neurilemma ***This is false; nerve fibers of the CNS (brain and spinal cord) are not enclosed by a neurilemma. This is why regeneration of severed axons is more difficult in the CNS (brain and spinal cord). The neurilemma (also called a sheath of Schwann, Schwann's membrane, or neurolemma) is the thin membrane spirally enwrapping the myelin layers of certain fibers, especially those of the peripheral nerves, or the axons of certain unmy¬elinated nerve fibers. 1. All axons of the PNS have a sheath of Schwann cells (and thus a neuri¬Notes lemma, made up of the outer layer of Schwann cells) around them. 2. When a Schwann cell is wrapped successively around an axon, it becomes a myelin sheath. Remember: Right-sided lesions of the spinal cord result in loss of motor activity on the same (ipsilateral) side and pain and temperature sensations on the opposite (contralateral) side.

Proteins that makes up the cell serve as all of the following EXCEPT one. Which one is the exception? • Transporters • Enzymes • Neurotransmitters • Receptors • Mediators

Neurotransmitters The proteins function as: • Transporters: they transport substances across the membrane • Enzymes: catalyze biochemical reactions • Receptors: bind hormones or growth factors • Mediators: aid in triggering a sequence of events Six Common Features of Biological Membranes: 1. Sheetlike structures, only a few molecules thick (60 to 100 A thick). 2. Consist mainly of lipids and proteins (carbohydrates are attached to exterior). 3. The membrane lipids are small molecules with hydrophobic and hydrophilic groups that form lipid bilayers in aqueous media. The hydrophobic center of the bilayer forms a barrier to the flow of polar molecules across the membrane. 4. The proteins function as transporters, enzymes, receptors, etc. 5. They are noncovalent assemblies. The protein and lipid molecules are held together by many noncovalent interactions. 6. They are asymmetric. The inside and outside faces are usually different. The plasma membrane has most of the carbohydrate (as glycoproteins and glycolipids) on the outer face while the lipids phosphatidylethanolamine and phosphatidylserine are more concentrated on the cytoplasmic face.

Cholinergic receptors are subclassified into which two categories? • Nicotinic and alpha • Alpha and beta • Nicotinic and muscarinic • Muscarinic and beta

Nicotinic and muscarinic Cholinergic receptors are membrane receptor proteins located on autonomic postganglionic neurons or on effector organs that are regulated by acetylcholine. Cholinergic receptors are subclassified into two categories, nicotinic and muscarinic, named for the extrinsic compounds that stimulate only that category. The properties of the two cat¬egories are summarized as follows: Nicotinic Receptors • Stimulated by ACh and nicotine, not stimulated by muscarine • Found at all ganglionic synapses • Also found at neuromuscular junctions • Blocked by hexamethonium Muscarinic Receptors • Stimulated by ACh and muscarine, not stimulated by nicotine • Found at target organs when ACh is released by postganglionic neurons (all of para¬sympathetic and some sympathetic) • Stimulated selectively by muscarine, bethanechol • Blocked by atropine Important: All preganglionic autonomic neurons (both sympathetic and parasympathetic) and all postganglionic parasympathetic neurons are cholinergic, meaning they use acetylcholine as a neurotransmitter. The cholinergic effects of preganglionic autonomic neurons (both sympathetic and parasympathetic) are excitatory. The cholinergic effects of postganglionic parasympathetic fibers can be either excitatory or inhibitory (e.g., parasympathetic fibers innervating the heart that cause slowing of the heart).

Which of the following are produced and released by the posterior pituitary?) • ADH • FSH • Oxytocin • Prolactin • Two of the above • None of the above

None of the above Oxytocin is secreted by the posterior portion of the pituitary (neurohypophysis) in response to dilation of the cervix and to suckling Oxytocin stimulates the smooth muscle of the uterus. Oxytocin also promotes the contraction of myoepithelial cells surrounding the sac-like alveoli of the mammary glands, resulting in the ejection of milk during breast-feeding. Oxytocin release causes a positive feedback mechanism to begin. Uterine contractions push the fetus against the cervical opening, which causes more oxytocin to be secreted. The rise in oxytocin causes greater uterine contractions, and the cycle continues until parturition is complete. Remember: Although both ADH and oxytocin are stored and released from the posterior portion of the pituitary (specifically, the pars nervosa), neither hormone is produced there. These hormones are manufactured by the hypothalamus, specifically the supraoptic and paraventricular nuclei. 1. ADH decreases the production of urine by increasing the reabsorption Notes of water by the renal tubules (ADH increases the water permeability of the collecting ducts and distal tubules). Without ADH, there would be extreme loss of water into the urine. 2. FSH stimulates growth of ovarian follicles and estrogen secretion. FSH Also promotes sperm maturation (in the testes). 3. Prolactin stimulates milk production and breast development.

Secretion of growth hormone is increased by all of the following EXCEPT one. Which one is the EXCEPTION? • Sleep • Stress • Obesity • Starvation • Exercise • Hypoglycemia

Obesity *** Secretion of growth hormone is decreased by somatostatin, somatomedins, obesity, hyperglycemia, and pregnancy. Growth hormone is a protein hormone of about 190 amino acids that is synthesized and se¬creted by cells called somatotrophs in the anterior pituitary. Growth hormone is a major par¬ticipant in control of several complex physiologic processes, including growth and metabolism. Physiologic Effects of Growth Hormone -- two distinct types of effects: • Direct effects are the result of growth hormone binding its receptor on target cells. Fat cells (adipocytes), for example, have growth hormone receptors, and growth hormone stim¬ulates them to break down triglyceride and suppresses their ability to take up and accumu¬late circulating lipids. • Indirect effects are mediated primarily by insulin-like growth factor-I (IGF-I), a hor-mone that is secreted by the liver and other tissues in response to growth hormone. A major¬ity of the growth promoting effects of growth hormone is actually due to IGF-I acting on its target cells. Production of growth hormone is modulated by many factors, including stress, exercise, nu-trition, sleep, and growth hormone itself. However, its primary controllers are two hypothal-amic hormones and one hormone from the stomach: • Growth hormone-releasing hormone (GHRH) is a hypothalamic peptide that stimulates both the synthesis and secretion of growth hormone. • Somatostatin (SS) is a peptide produced by several tissues in the body, including the hy¬pothalamus. Somatostatin inhibits growth hormone release in response to GHRH and to other stimulatory factors such as low blood glucose concentration. • Ghrelin is a peptide hormone secreted from the stomach. Ghrelin binds to receptors on so¬matotrophs and potently stimulates secretion of growth hormone. Growth hormone undersecretion produces pituitary dwarfism in children. Oversecretion of growth hormone causes gigantism in children or, in adults, acromegaly.

I Which of the following characteristics is shared by simple and facilitated diffusion of glucose? • It is saturable • Requires metabolic energy • Occurs down an electrochemical gradient • Require a Na gradient

Occurs down an electrochemical gradient *** Both types of transport occur down an electrochemical gradient ("downhill'), and do not require metabolic energy. Processes by which substances are transferred across cell membranes: • Diffusion: the process by which molecules spread from areas of high concentration, to areas of low concentration. Oxygen enters the cell in this manner. Oxygen moves from the blood, where it is concentrated, to the inside of the cell, where it is not concentrated. Note: When the molecules are even throughout a space -- it is called equilibrium. • Osmosis: a type of diffusion, but involving only the movement of water across the mem¬brane. The water moves to the side of the membrane that contains the most molecules of solute dissolved in it. *** Diffusion and osmosis are both types of passive transport -- that is, no energy is re-quired for the molecules to move into or out of the cell. • Facilitated diffusion: a process whereby a substance passes through a membrane with the aid of an intermediary or a facilitator. The facilitator is an integral membrane protein that spans the width of the membrane. The force that drives the molecule from one side of the membrane to the other is diffusion. • Active transport: the pumping of molecules or ions through a membrane against their concentration gradient. It requires a transmembrane protein (usually a complex of them) called a transporter and energy. The source of this energy is ATP. Important: Most mammalian cells transport glucose through a family of membrane proteins known as glucose transporters (Glut or SLC2A family). Glut-1 mediates glucose transport into red cells, and throughout the blood brain barrier. It is ubiquitously expressed and transports glucose in most cells.Glut-2 provides glucose to the liver and pancreatic cells. Glut-3 is the main transporter in neurons, whereas Glut-4 is primarily expressed in muscle and adipose tissue and regulated by insulin. Glut-5 transports fructose in the intestine and testis.

Somatostatin acts by both endocrine and paracrine pathways to affect its target cells. A majority of the circulating somatostatin appears to come from the and • Gallbladder, large intestine • Pancreas, gastrointestinal tract • Stomach, adrenal medulla • Bladder, small intestine

Pancreas, gastrointestinal tract Somatostatin was first discovered in hypothalamic extracts and identified as a hormone that inhibited secre¬tion of growth hormone. Subsequently, somatostatin was found to be secreted by a broad range of tissues, in¬cluding: the pancreas, intestinal tract, and regions of the central nervous system outside the hypothalamus. Somatostatin acts by both endocrine and paracrine pathways to affect its target cells. A majority of the circu¬lating somatostatin appears to come from the pancreas and gastrointestinal tract. If one had to summarize the effects of somatostatin in one phrase, it would be: "somatostatin inhibits the secretion of many other hor¬mones." Effects of somatostatin: • Inhibits the secretion of growth hormone from the pituitary gland • Inhibits the secretion of both insulin and glucagon • Inhibits the secretion of many of the other GI hormones, including gastrin, cholecystokinin, secretin, and vasoactive intestinal peptide

Which of the following is a component of coenzyme A? • Riboflavin • Niacin • Pantothenic acid • Biotin This is also a component of: • Fatty acid synthase • DNA polymerase • Phosphofructokinase • Adenylate cyclase

Pantothenic acid -- also called pantothenate or vitamin B5 Fatty acid synthase Pantothenic acid (PA), a water-soluble B-complex vitamin, is essential for growth, reproduction, and normal physiological functions. Pantothenic is a component of coenzyme A, which functions in the transfer of acyl groups. Coenzyme A contains a thiol group that carries acyl compounds as activated thiol esters. Examples of such structures are succinyl-CoA, fatty acyl-CoA and acetyl-CoA.

A patient of yours is deficient in niacin. This disease is termed: • Night blindness • Pellagra • Scurvy • Rickets • Beriberi

Pellagra 1. Niacin is also called nicotinic acid. Notes 2. It is a component of NAD+ and NADP.. 3. It can be formed from the amino acid tryptophan. 4. High supplemental doses are effective in treating hyperlipidemia.

Enzyme Deficiency Diseases: Cause or Enzyme That is Deficient Results of Deficiency Disease Phenylketonuria Maple syrup urine disease Alcaptonuria Cystinuria Albinism

Phenylalanine hydroxylase Alpha-keto acid dehydrogenase Homogentisic acid oxidase Deficiency of the intestinal and kidney transport protein of cystine Tyrosinase Appearance of phenylalanine and its degradation products (e.g., phenylketones) in the urine Branched amino acids (valine, isoleucine, and leucine) are excreted in the urine Oxidized products of homogentisic acid give urine a dark color Kidney stones Defect of melanin production that results in partial or full absence of pigmentation

ATP is produced by humans via all of the following EXCEPT which two? ) • Substrate-level phosphorylation • Electron-transport/oxidative phosphorylation • Photophosphorylation • Pentose phosphate pathway

Photophosphorylation Pentose phosphate pathway Remember: No ATP is directly consumed or produced in the pentose phosphate pathway. This pathway provides a major portion of the cell's NADPH, which functions as a biochemical reductant. • Substrate-level phosphorylation: high-energy phosphate intermediates are formed and are transferred to ADP to produce ATP. Examples of this are found in glycolysis and the citric acid cycle (Krebs cycle). Glycolysis is the first phase, and the Krebs cycle (citric acid cycle) is the second phase of the respiratory metab¬olism of glucose. • Electron-transport/oxidative phosphorylation: electrons move down the electron transport chain, and chemiosmosis occurs. Because the electrochemical gradient generated by the transfer of electrons through the electron transport chain to 02 is used in the production of ATP, the overall process is known as electron transport/oxidative phosphorylation. It is the third and final phase of the respiratory metabolism of glucose and other substrates. Reduced coenzymes (NADH and FADH2) generated earlier in glycolysis and the Krebs cycle are reoxidized; the electrons these processes release are transported through a series of membrane bound carriers (flavoproteins, iron-sulfur proteins, coenzyme Q, and cytochromes) to establish a proton gradient across a membrane, a terminal acceptor such as oxygen is reduced, and ATP is synthesized by chemiosmosis. Note: Oxidative phosphorylation is the major source of ATP in aerobic organisms. • Photophosphorylation: occurs as a result of photosynthesis (which also invol¬ves an electron transport chain). Note: Oxygen uptake, which is dependent on the presence of ADP, phosphate, and an electron donor, is termed coupled respiration.

The amount of T4 produced and released by the thyroid gland is controlled by the? • Hypothalamus • Medulla oblongata • Parathyroid gland • Pituitary gland

Pituitary gland The thyroid gland is a small gland, normally weighing less than one ounce, located in the front of the neck. The thyroid gland is made up of two halves, called lobes, that lie along the trachea and are joined together by a narrow band of thyroid tissue, known as the isthmus. The function of the thyroid gland is to take iodine, found in many foods, and convert it into thyroid hormones: thyroxine (T4) and triiodothyronine (T3). Thyroid cells are the only cells in the body that can absorb iodine. These cells combine iodine and the amino acid tyrosine to make T3 and T4. T3 and T4 are then released into the bloodstream and are transported throughout the body where they control metabolism. Every cell in the body depends upon thyroid hormones for regulation of cell metabolism. The normal thyroid gland produces about 80% T4 and about 20% T3; however, T3 possesses about 4 times the hormone "strength" as T4. The thyroid gland is under the control of the pituitary gland, a small gland the size of a peanut at the base of the brain. When the level of thyroid hormones (7'3 and 7'4) drops too low, the pituitary gland produces thyroid-stimulating hormone (TSH or thyrotropin), which stimulates the thyroid gland to produce more hormones. The pituitary gland itself is regulated by the hypothalamus. The hypothalamus produces thyroid-releasing hormone (TRH), which tells the pituitary gland to stimulate the thy¬roid gland (by releasing TSH). 1. Thyroid hormones increase glycogenolysis, gluconeogenesis, lipolysis, protein synthesis, and degradation. 2. Thyroid hormones stimulate bone maturation as a result of ossification and fusion of the growth plates. 3. Thyroid hormones are lipophilic hormones that exert their effects via transcriptional processes.

The major intracellular cation is: • Sodium • Potassium • Magnesium • Chromium

Potassium Functionally, the body's water is effectively compartmentalized into two major fluid compart¬ments: Intracellular Fluid (ICF) comprises 2/3 of the body's water. • If the body has 60% water, the ICF is about 40% of the weight. • The ICF is primarily a solution of potassium and organic anions, proteins, etc. • The cell membranes and cellular metabolism control the constituents of this ICF. • The ICF is not homogeneous in the body. The ICF represents a conglomeration of fluids from all the different cells Extracellular Fluid (ECF) is the remaining 1/3 of the body's water. • The ECF is about 20% of the weight. • The ECF is primarily a NaCl and NaHCO3 solution. • The ECF is further subdivided into three subcompartments: 1. Interstitial fluid (ISF) surrounds the cells, but does not circulate. It comprises about 3/4 of the ECF. 2. Plasma circulates as the extracellular component of blood. Plasma makes up about 1/4 of the ECF. 3. Transcellular fluid is a set of fluids that are outside of the normal compartments. These 1-2 liters of fluid make up the CSF, digestive juices, mucus, etc. The 60-40-20 Rule: • 60% of body weight is water • 40% of body weight is intracellular fluids • 20% of body weight is extracellular fluid 1. All the body's fluid compartments are in osmotic equilibrium (except for transient Notes changes). 2. The ions and small solutes that constitute the ECF are in equilibrium with similar concentrations in each subcompartment. 3. The ECF volume is proportional to the total Na content.

The famous relationship stated in the Henderson-Hasselbalch equation can be used to: • Predict the pH that acid buffers work best at • Predict the pKa that acid buffers work best at • Predict the dissociation constant of a weak acid only • Predict the dissociation constant of a strong acid only • Predict the dissociation constant of any acid

Predict the pH that acid buffers work best at -- the relationship cannot predict any dissociation constants Buffers must be chosen for the appropriate pH range that they are called on to control. The pH range of a buffered solution is given by the Henderson-Hasselbalch equation. This equation describes the relationship between the pH, pK (the negative log of the dissociation constant), and the concentrations of an acid and its conjugate base. The equation is simply a useful way of restating the expression for the dissociation constant of an acid (Ka). The dissociation constant of an acid (Ka) is: K[11+] [A ] = a [HA] Note: The larger the Ka, the stronger the acid, because most of the HA has been converted into H, and A-. Conversely, the smaller the Ka, the less acid has dissociated, and therefore the weaker the acid. The Henderson-Hasselbalch Equation was derived from the equation for the dissociation constant: pH = pKa + log [A] [HA] 1. The Henderson-Hasselbalch equation shows that pH=pK when an acid is Notes half neutralized. 2. The pH of a buffer system depends on the pK of the weak acid and the ratio of molar concentrations of salt and weak acid. 3. The optimum pH for an enzyme is the pH of the most rapid reaction rate.

All of the following are actions of estrogen EXCEPT one. Which one is the EXCEPTION? • Causes the development of female secondary sex characteristics at puberty • Causes the development of the breasts • Maintains pregnancy • Promotes secretory changes in the uterine endometrium during the latter half of the monthly female sexual cycle, thus preparing the uterus for implantation of the fertilized ovum

Promotes secretory changes in the uterine endometrium during the latter half of the monthly female sexual cycle, thus preparing the uterus for implantation of fertilized ovum *** Important: This is the most important function of progesterone, not estrogen. On average, females reach puberty 1 or 2 years earlier than males. In females, puberty is marked by the first episode of menstrual bleeding, which is called menarche. At puberty, an alteration in brain function leads to increased gonadotropin-releasing hormone (Gn-RH) secretion by the hypothalamus. Gn-RH stimulates the secretion of FSH and LH by the anterior pituitary gland, which ultimately leads to an increased production of estrogens (androgen hormone) by the ovaries. The events of puberty in the female (such as enlargement of the vagina, uterus, and uterine tubes; deposition of fat in the breasts and hips) are largely a result of increased production of estrogens by the ovaries. Estrogen is effective at very low concentrations and generates a slowly developing long-term response in target tissues by binding to an intracellular receptor.

Afferent nerve endings in joints and tendons are called: ) • Exteroreceptors • Visceroreceptors • Proprioreceptors

Proprioceptors *** Proprioceptors are a type of afferent nerve endings relaying information about body position and movement, the extent of stretch or force of muscle contraction. Example: sensory receptors of the stretch reflex. Receptors are structures that are generally activated by changes (stimuli) in either the internal or external environment of the body. As a result of the activity of these receptors, nerve impulses are initiated within sensory nerve cells. Receptors are classified broadly as interoreceptors (visceroreceptors) or exteroreceptors. Exteroreceptors are the sensory nerve endings associated with the skin that provide information about the external environment. Visceroreceptors are associated with the viscera or organs and provide information about the internal environment. More specific classification involves reference to the type of stimulus monitored by a receptor. For example, your body has chemoreceptors, baroreceptors, photoreceptors, and mechanoreceptors. These monitor shifts in chemistry, blood pressure, light, and touch, respectively. All receptors are linked to sensory neurons. When a receptor responds to a stimulus, a signal is sent along the sensory neuron to the CNS (brain or spinal cord). Within the CNS, the stimulus is identified, and if a response is required to maintain homeostasis, signals are sent to effectors along motor neurons. 1. Adaptation is the decreased sensitivity to a continued stimulus. Notes' 2. Free nerve endings respond to itch, movement, pain, and temperature. Examples include nociceptors, Merkel discs, and root hair plexuses.

Reabsorption of glomerular filtrate would be most affected if modifications were made to the permeability to which section of the nephron? • Descending loop of Henle • Distal convoluted tubule • Proximal convoluted tubule • Ascending loop of Henle

Proximal convoluted tubule *** Approximately 2/3 of the glomerular filtrate is reabsorbed in the proximal convoluted tubule. This includes almost 100% of the filtered glucose and amino acids. Glomerular filtration is the filtration process as blood flows through the kidney. Some of the plasma (16% to 20%) is filtered out of the glomerular capillaries and into the glomerular capsules of the renal tubules as the glomerular filtrate. This filtrate contains most plasma components but is free of large proteins. The Excretion Rate = The Filtration Rate - Reabsorption + Secretion Reabsorption is the movement of solutes from tubular fluid into interstitial fluid. Reabsorption takes place not only in the proximal tubule but also in the loop of Henle, the distal convoluted tubule, and the collecting duct. Processes include: primary active transport, secondary active transport, facilitated diffusion, simple diffusion, and solvent drag. Transport can be either transcellular or paracellular. Secretion is the movement of solutes from the interstitial fluid into the tubular fluid.

The starting point of gluconeogenesis is: ) • Lactic acid • Pyruvic acid • Amino acids • Acetyl-CoA

Pyruvic acid Gluconeogenesis is the process of synthesizing glucose from non-carbohydrate sources. The starting point of gluconeogenesis is pyruvic acid, although oxaloacetic acid and dihydroxyacetone phosphate also provide entry points. Lactic acid, some amino acids from protein, and glycerol from fat can be converted into glucose. Gluconeogenesis is similar but not the exact reverse of glycolysis. Gluconeogenesis occurs mainly in the liver with a small amount also occurring in the cortex of the kid-ney. Very little gluconeogenesis occurs in the brain, skeletal muscles, heart muscles, or other body tis¬sue. In fact, these organs have a high demand for glucose. Therefore, gluconeogenesis is constantly occurring in the liver to maintain the glucose level in the blood to meet these demands. Remember: During starvation, however, the brain can derive energy from ketone bodies, which are converted to Gluconeogenesis is a pathway consisting of 11 enzyme-catalyzed reactions. • Gluconeogenesis begins in the mitochondria with the formation of oxaloacetate through carboxylation of pyruvate at the expense of one molecule of ATP. This reaction is catalyzed by pyruvate carboxylase, which is stimulated by high levels of acetyl-CoA (when fatty acid oxidation is high in the liver) and inhibited by high levels of ADP. • Oxaloacetate must then be reduced into malate using NADH in order to be transported out of the mitochondria. • In the cytoplasm, malate is oxidized to oxaloacetate using NAD+, where the remaining steps of gluconeogenesis occur. • Oxaloacetate is then decarboxylated and phosphorylated to produce phosphoenolpyruvate by phosphoenolpyruvate carboxykinase. One molecule of GTP is hydrolyzed to GDP in the course of this reaction. • The next steps in the reaction are the same as reversed glycolysis. However, fructose-1,6-bisphosphatase converts fructose-1,6-bisphosphate to fructose-6-phosphate. The pur¬pose of this reaction is to overcome the large negative AG. • Glucose-6-phosphate is formed from fructose-6-phosphate by phosphoglucoisomerase. Glucose-6-phosphate can then be used for glucose generation or in other metabolic path¬ways. Free glucose is not generated automatically because glucose, unlike glucose-6¬phosphate, tends to freely diffuse out of the cell. • The final reaction of gluconeogenesis, the formation of glucose, is carried out in the lumen of the endoplasmic reticulum. Glucose-6-phosphate is hydrolyzed by glucose-6- phosphatase to produce glucose. Glucose is then shuttled into the cytosol by glucose trans¬porters located in the membrane of the endoplasmic reticulum.

a Which of the following cells in the body metabolize glucose only through the anaerobic glycolytic pathway? • Muscle cells • Red blood cells • Hepatocytes • Neural cells

Red blood cells *** Though they are never really in an oxygen-deprived environment, they do not have mi-tochondria and therefore cannot send pyruvate to the citric acid cycle. The oxidation of glucose is known as glycolysis. Glucose is oxidized to either lactate or pyru¬vate. Under aerobic conditions, the dominant product in most tissues is pyruvate, and the pathway is known as aerobic glycolysis. When oxygen is depleted, as for instance during prolonged vigorous exercise, the dominant glycolytic product in many tissues is lactate, and the process is known as anaerobic glycolysis. Glycolysis occurs in the cytosol of all cells in the body. Glycolysis starts with a molecule of glucose and then performs 10 stepwise chemical transformations. During this process, the sugar molecule is primed with two phosphates (using up two ATP molecules), then broken into two pieces, and finally reshaped and dehydrated, forming four ATP molecules in the process. Overall, glycolysis builds two new ATP molecules using the energy of this partial breakdown of sugar. The ATP may then be used to power molecular processes throughout the cell. In addition, one step in glycolysis also extracts four hydrogen atoms from the sugar molecule, which may be used for biosynthesis or to create additional chemical energy. Pyruvate is the end product of glycolysis in cells with mitochondria and an adequate supply of oxygen. This series of 10 reactions is called aerobic glycolysis because oxygen is required to reoxidize the NADH formed during the oxidation of glyceraldehydes¬3-phosphate. Aerobic glycolysis sets the stage for the oxidative decarboxylation of pyruvate to acetyl-CoA, a major fuel of the citric acid cycle. Alternatively, glucose can be converted to pyruvate, which is reduced by NADH to form lactate. This conversion is called anaerobic glycolysis because there is no net formation of NADH, and therefore, this conversion can occur in the absence of oxygen. Anaerobic glycolysis allows the production of ATP in tissues that lack mitochondria (for example, red blood cells) or in cells deprived of sufficient oxygen.

Surfactant: • Reduces the surface tension in pulmonary alveoli • Increases the Pco2 levels in blood • Is a mucous secreted by goblet cells • Reduces friction in the pleural cavity

Reduces the surface tension in pulmonary alveoli Small septal cells, dispersed among cells of the simple squamous epithelium lining a pulmonary alveolus, secrete a phospholipid surfactant that lowers the surface tension in the pulmonary alveoli. This reduction in surface tension prevents small alveoli from collapsing and increases compliance. Asthma is a chronic reactive airway disorder that causes episodic airway obstruction. Such obstruction results from bronchospasm, increased mucous secretion, and mucosal edema. Asthma is a type of chronic obstructive pulmonary disease, a group of lung diseases characterized by increased airflow resistance. The immediate consequences of a patient having an asthmatic attack include: hypoxia, tachycardia, hypercapnia, and acute respiratory acidosis. Important: The cause of airway obstruction in asthma is bronchiolar constriction. Beta¬2-adrenergic stimulation (beta-2-adrenergic agonists) produces relaxation of the bron¬chioles. Beta-2-agonists are the most effective bronchodilators available and are rela¬tively free of unwanted effects. Short-acting beta-2-agonists are useful for symptom relief. Examples of short-acting beta-2-agonists include: salbutamol and terbuta¬line. Long-acting beta-2-agonists have been a significant advance in asthma management. They cause bronchodilation for more than 12 hours and, when taken twice daily, improve symptom control. It is important that long-acting beta-2-agonists should only be used in conjunction with inhaled steroids. Examples of long-acting beta-2-agonists include: salmeterol and formoterol.

Parathyroid hormone causes which of the following to occur? • Removal of Ca via the kidney • Removal of Ca from bone • Removal of Ca via the GI system • None of the above

Removal of Ca from bone Parathyroid hormone (PTH) is secreted by chief cells in the parathyroid gland in response to decreased plasma-calcium levels. The plasma-calcium level is the major controller of parathyroid hormone secretion. PTH is a principal controller of calcium and phosphate metabolism and is involved in the remodeling of bone. PTH increases the plasma-calcium concentration and decreases the plasma-phosphate concentration. PTH has three modes of action: 1. Increases calcium removal from storage in bone and increases absorption of calcium by intestines, increasing blood calcium levels. 2. Acts on the kidneys to decrease calcium excretion and increase phosphate excretion in the urine. Also stimulates 1-alpha-hydroxylase in the kidneys. 3. Increases the absorption of calcium in the GI tract. 1. Hyperparathyroidism (von Recklinghausen's disease) causes extensive Notes bone decalcification and is marked by extremely high blood calcium levels and low blood phosphate levels. This leads to muscular weakness. 2. Hypoparathyroidism (tetany) causes decreased bone resorption, decreased renal Cat, reabsorption, increased renal phosphate reabsorption, and decreased production of the active form of vitamin D (1,25- dihydroxycholecalciferol). Together, these effects decrease serum calcium and increase serum phosphate. ***A diet deficient in calcium will result in production of PTH and bone resorption.

Biotin is: • The precursor of FAD • Required for the carboxylation of acetyl-CoA to malonyl-CoA, an intermediate in fatty acid synthesis • A cofactor required for the hydroxylation of proline and lysine • A fat-soluble vitamin

Required for the carboxylation of acetyl-CoA to malonyl-CoA, an inter¬mediate in fatty acid synthesis 1. Biotin (sometimes called vitamin H) is also synthesized by intestinal Notes bacteria. 2. Avidin is a protein, found in uncooked egg whites, that binds to and inactivates biotin and that, when present in abundance, can result in a deficiency of biotin.

The volume of air remaining in the lungs after a maximal expiration is called the • Vital capacity (VC) • Tidal volume (TV) • Residual volume (RV) • Functional residual capacity (FRC)

Residual volume (RV) *** Determined by the force generated by the muscles of expiration and the inward elastic recoil of the lungs as they oppose the outward elastic recoil of the chest wall. The residual volume of a healthy 70-kg adult is 1.5 liters. Lung Volumes and Capacities: • Total lung capacity (TLC) is the volume of air in the lungs after a maximal inspir-atory effort. Determined by the strength of contraction of the inspiratory muscles in opposition to the inward elastic recoil of the lungs and chest wall. This is about 6 liters in a healthy 70-kg adult. • Vital capacity (VC) is the volume of air expelled from the lungs during a maximal forced expiration starting after a maximal forced inspiration. VC 4.5 liters. VC = TV + IRV + ERV • Tidal volume (TV) is the volume of air entering or leaving the nose or mouth per breath. During normal, quiet breathing (eupnea), the tidal volume of a 70-kg adult is about 500 ml per breath. Note: The normal rate of respiration is about 12 times per minute. • Functional residual capacity (FRC) is the volume of gas remaining in the lungs at the end of a normal tidal expiration. This is the balance point between the inward elastic recoil of the lungs and the outward elastic recoil of the chest wall. FRC is about 3 liters in a healthy 70-kg adult. FRC = ERV + RV • Inspiratory reserve (IRV) is the volume of gas inhaled into the lungs during a max-imal forced inspiration starting at the end of a normal tidal inspiration. IRV is about 2.5 liters. • Expiratory reserve (ERV) is the volume of gas expelled from the lungs during a maximal forced expiration that starts at the end of normal tidal expiration. ERV is about 1.5 liters.

Alveolar ventilation is expressed as: ) • Respiratory rate x (Tidal volume + Dead air space volume) • Respiratory rate + (Tidal volume + Dead air space volume) • Respiratory rate x (Tidal volume — Dead air space volume) • Respiratory rate — (Tidal volume — Dead air space volume)

Respiratory rate x (Tidal volume — Dead air space volume) The exchange of oxygen and carbon dioxide between the lungs and the blood occurs within the alveoli located in respiratory bronchioles, alveolar ducts, and alveolar sacs. No gas exchange takes place within the remaining respiratory passageways (nose, pharynx, trachea, and conducting bronchioles). These air-filled passageways are called anatomical dead air space. During quiet breathing, the amount of air brought into the lungs is the tidal volume (500 ml). Approximately 150 ml of that volume remains in the dead air space. The volume of atmospheric air that actually reaches the alveoli (either per breath or in one minute) and that can participate in the exchange of gases between the alveoli and the blood is called the alveolar ventilation. 1. Alveolar ventilation is a good criterion for the effectiveness of breathing. 2. Respiratory rate = Breaths/min 3. Minute ventilation = Tidal volume x Breath/min.

Which of the following is a water-soluble vitamin that acts as an essential coenzyme in many oxidation-reduction reactions involved with carbohydrate metabolism? 1 • Folacin (folic acid) • Riboflavin (vitamin B2) • Niacin • Thiamine (vitamin B1)

Riboflavin (Vitamin B2) Vitamin B2, commonly called riboflavin, is one of eight water-soluble B vitamins. In addition to producing energy for the body, riboflavin also works as an antioxi¬dant by scavenging damaging particles in the body known as free radicals. These particles occur naturally in the body but can damage cell membranes, interact with genetic material, and possibly contribute to the aging process as well as the development of a number of health conditions such as heart disease and cancer. Antioxidants such as riboflavin can neutralize free radicals and may reduce or even help prevent some of the damage they cause. The two biologically active forms are flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) formed by the transfer of an AMP moiety from ATP to FMN. FMN and FAD are bound tightly -- sometimes covalently -- to flavoenz¬ymes that catalyze the oxidation or reduction of a substrate. Note: Vitamin D and parathyroid hormone both increase serum calcium.

All of the following are factors that decrease insulin secretion EXCEPT one. Which one is the EXCEPTION? • Decrease in blood glucose level • Secretion of somatostatin • Secretion of glucagon • Secretion of either epinephrine or norepinephrine

Secretion of glucagon *** The secretion of glucagon causes an increase in insulin secretion. Insulin is secreted by the beta cells in the islets of Langerhans of the pancreas in response to a rise in the blood glucose level. Insulin causes glycogenesis in the liver (conversion of glucose to glycogen). Insulin lowers blood glucose levels by stimulating and facilitating the uptake of glucose and the utilization of glucose as an energy source by many cells. Insulin also promotes the synthesis of glycogen, triglycerides, and proteins. Insulin release by the beta cells is promoted by the following: • A rise in blood glucose level (hyperglycemia) -- this is the major factor governing insulin release. • Elevated level of amino acids (especially arginine, lysine, and leucine) in the blood plasma. • Glucagon, GH, and cortisol. • Parasympathetic stimulation. Note: Sympathetic stimulation or epinephrine inhibits insulin release. Important: Insulin inhibits lipolysis (it enhances triglyceride synthesis) and stimulates protein synthesis (inhibits protein breakdown). In other words, insulin conserves proteins, carbohydrates, and fats in the body. The removal of the anterior portion (adenohypophysis) of the pituitary gland results in increased sensitivity to insulin. Clinical manifestations of hypoglycemia include: hunger, nervousness, and shakiness, perspiration, dizziness or light-headedness, sleepiness, confusion, difficulty speaking, and feeling anxious or weak. Important: Seizures can occur as a result of severely low glucose levels.

All of the following statements are true EXCEPT one. Which one is the EXCEPTION? • During early childhood, a boy does not secrete gonadotropins, and thus has little circulating testosterone • Secretion of gonadotropins from the adrenal gland, which usually occurs between the ages 10 and 15, marks the onset of puberty • These pituitary gonadotropins stimulate testes functioning as well as testosterone secretion • During puberty, the penis and testes enlarge, and the male reaches full adult sexual and reproductive capability • Puberty also marks the development of male secondary sexual characteristics

Secretion of gonadotropins from the adrenal gland, which usually occurs between the ages 10 and 15, marks the onset of puberty *** This is false; secretion of gonadotropins from the pituitary gland, which usually occurs between the ages of 10 and 15, marks the onset of puberty. At puberty, an alteration in brain function leads to an increased production of gonadotropin-releasing hormone (Gn-RH) by the hypothalamus. Gn-RH stimulates the secretion of FSH and LH (gonadotropins) by the anterior pituitary gland. These gonadotropins stimulate the growth and function of the testes. Specifically, FSH promotes the maturation of sustentacular cells (Sertoli cells), which are involved in the development and maturation of sperm. LH stimulates the interstitial cells (Leydig cells) of the testes to produce testosterone. The onset of puberty varies but most commonly occurs between 10 and 15 years of age. The events of puberty (for example, enlargement of the penis, scrotum, and testes; characteristic hair growth; and voice changes) result from increased testosterone production by the testes. Note: The changes above are called secondary sex characteristics. Remember: A male child is considered to have reached his full adult sexual capabilities at the end of puberty. This means that after puberty the male child is capable of reproduction. Note: Precocious puberty is a condition in which the changes associated with puberty begin at an unexpectedly early age and is due to an excess of androgenic (in boys) and estrogenic (in girls) substances produced by the adrenal cortex. These substances resemble the male and female sex hormones

The kidneys regulate acid-base balance by the: • Secretion of bicarbonate ions (HCO3) into the renal tubules and the reabsorption of hydrogen ions (fr) • Secretion of hydrogen ions (H) into the renal tubules and the reabsorption of bicarbonate ions (HCO3) • Secretion of both hydrogen (E) and bicarbonate ions (HCO3) into the renal tubules • Reabsorption of both hydrogen (H) and bicarbonate ions (HCO3)

Secretion of hydrogen ions (H) into the renal tubules and the reabsorption of bicarbonate ions (HCO3) There are three primary systems that regulate the hydrogen ion concentration in the body flu¬ids: 1. The chemical acid base buffer system of the body fluids, which immediately combine with acid or base to prevent excessive changes in hydrogen ion concentration. 2. The respiratory center, which regulates the removal of CO2 (and therefore H2CO3) from the extracelluar fluid. 3. The kidneys, which can excrete either acid or alkaline urine, thereby readjusting the extracellular fluid hydrogen ion concentration toward normal during acidosis or alkalo-sis. *** The kidneys, although providing the most powerful of all the acid-base regula-tory systems, require many hours to several days to readjust the hydrogen ion concentration. The hydrogen ions are secreted into the tubules by tubular cells. The secretion mechanism derives hydrogen ions from carbonic acid. The enzyme carbonic anhydrase is present within tubular cells, and it catalyzes the formation of carbonic acid from carbon dioxide and water. The carbonic acid dissociates into hydrogen ions (H+) and bicarbonate ions (HCO3). The H- ions are secreted into the tubules, and the the HCO3 ions pass out of the tubular cells and into the blood. Phosphate compounds (HPO4) and ammonia (NH) act as buffers to tie up hydrogen ions in the tubular fluid. Phosphate compounds are excreted in combination with a cation such as sodium (Na+). Ammonium ions are excreted in combination with anions such as chloride (Cl). 1. Ammonia is formed in the tubular cells by the deamination of certain amino Notes. acids, particularly glutamic acid. 2. Phosphate and ammonium excretion measurements provide good information on how much acid is being eliminated by the kidneys.

A patient deficient in production of tyrosine would also be deficient in all of the following EXCEPT one. Which one is the EXCEPTION? • Catecholamines • Melanin • Thyroxine • Serotonin

Serotonin Tyrosine is not essential to the human diet, since this amino acid can be synthesized in the body from phenylalanine. Tyrosine is a precursor of the adrenal hormones epinephrine and norepinephrine as well as of the thyroid hormones, including thyroxine. Tyrosine is also the precursor to the neurotransmitter dopamine. Melanin, the skin and hair pigment, is also derived from this amino acid. Remember: Serotonin (also called 5-hydroxytryptamine) is synthesized from the amino acid tryptophan. Serotonin is released from platelets upon damage to the blood vessel walls. Serotonin acts as a potent vasoconstrictor and increases vascular peripheral resistance. In gastric mucous membranes, serotonin is secreted by the enteroendocrine cells and causes the smooth muscle to contract. In the brain, sertonin acts as a neurotransmitter. Note: Lysergic acid diethylamide interferes with the action of serotonin in the brain.

In what order does vitamin D get converted from its inactive to its fully active form? • Skin, liver, kidney • Skin, kidney, liver • Liver, kidney, skin • Liver, skin, kidney • Kidney, liver, skin • Kidney, skin, liver

Skin, liver, kidney 7-dehydrocholesterol, an intermediate in cholesterol synthesis, is converted to cholecalciferol (vitamin D3) in the dermis and epidermis of humans exposed to sun¬light. Note: Preformed vitamin D is a dietary requirement only in individuals with limited exposure to sunlight. Vitamin D3 (cholecalciferol) is not biologically active, but is a precursor of the active molecule 1, 25-dihydroxycholecalciferol. The most prominent actions of this active molecule are to regulate the plasma levels of calcium and phosphorus. Note: Cholecalciferol (vitamin D3) is converted to 25-hydroxycho-(...alciferol in the liver. 25-hydroxycholecalciferol is converted to 1,25-dihydroxychotecalciferol in the kidney.

Molecules that can easily penetrate a biologic membrane are usually: • Large and nonpolar • Small and polar • Large and polar • Small and nonpolar

Small and nonpolar The most important property of the lipid bilayer is that it is a highly impermeable structure. Impermeable simply means that it does not allow molecules to freely pass across it. Only water and gases (for example 02, CO2) can easily pass through the bilayer. This property means that large molecules and small polar molecules cannot cross the bilayer, and thus the cell membrane, without the assistance of other structures. Important: Molecules and ions that are large and polar move across the membrane via active transport systems that involve binding molecules that are classified as proteins. Another important property of the lipid bilayer is its fluidity. The lipid bilayer contains lipid molecules. The bilayers' fluidity allows these structures mobility within the lipid bilayer. This fluidity is biologically important, influencing membrane transport. Fluidity is dependent on both the specific structure of the fatty acid chains and temperature (fluidity decreases with lower temperature and increases with increased temperature). Remember: • Polar: hydrophilic, or "water-loving;" describing molecules or groups that are soluble in water (e.g., ions, glucose, and urea) • Nonpolar: hydrophobic; describing molecules or groups that are poorly soluble in water (e.g., oxygen, carbon dioxide, and alcohol) Hydrophobic molecules are transported across cell membranes by simple diffusion. Hydrophilic molecules require a carrier protein to cross the cell membrane. Note: Sodium is not very permeable to the cell membrane.

The tick ascending limb of the loop of henle is called the diluting segment because: • Sodium chloride (NaC1) is reabsorbed with a proportional amount of water • Water is reabsorbed from the tubular lumen • Water is secreted into the tubular lumen • Sodium chloride (NaC1) is reabsorbed without water • Sodium chloride (NaC1) is reabsorbed and water is secreted

Sodium chloride (NaCI) is reabsorbed without water The nephron is the basic structural and functional unit of the kidney. The nephron's chief func¬tion is to regulate the concentration of water and soluble substances like sodium salts by filter- ing the blood, reabsorbing what is needed, and excreting the rest as urine. Two general classes of nephrons are cortical nephrons and juxtamedullary nephrons. Cor¬tical nephrons have their renal corpuscle in the superficial renal cortex, while the renal corpus¬cles of juxtamedullary nephrons are located near the renal medulla. Functionally, cortical and juxtamedullary nephrons have distinct roles. Cortical nephrons (85% of all nephrons) mainly perform excretory and regulatory functions, while juxtamedullary nephrons (15% of nephrons) concentrate and dilute urine. The flow of the renal tubule is as follows: • The proximal tubule: Fluid in the filtrate entering the proximal convoluted tubule is reab¬sorbed into the peritubular capillaries, including approximately two-thirds of the filtered salt and water and all filtered organic solutes (primarily glucose and amino acids). • The loop of Henle extends from the proximal tube and consists of a descending limb and as¬cending limb. The loop of Henle begins in the cortex, receiving filtrate from the proximal convoluted tubule, extends into the medulla, and then returns to the cortex to empty into the distal convoluted tubule. The loop of Henle's primary role is to concentrate the salt in the in¬terstitium, the tissue surrounding the loop. 1. Its descending limb is permeable to water but completely impermeable to salt, and thus only indirectly contributes to the concentration of the interstitium. 2. Unlike the descending limb, the ascending limb of the loop of Henle is impermeable to water, a critical feature of the countercurrent exchange mechanism employed by the loop. The ascending limb actively pumps sodium out of the filtrate, generating the hyper-tonic interstitium that drives countercurrent exchange. • Much of the ion transport taking place in the distal convoluted tubule is regulated by the endocrine system. In the presence of parathyroid hormone, the distal convoluted tubule re¬absorbs more calcium and excretes more phosphate. When aldosterone is present, more sodium is reabsorbed, and more potassium excreted.

The only membrane phospholipid not derived from glycerol is: ) • Lecithin • Sphingomyelin • Cerebroside • Cardiolipin

Sphingomyelin *** Most membrane phospholipids contain glycerol (lecithin, cerebroside, and cardiolipin). Sphingomyelin is an exception and is based on sphingosine. Phospholipids are lipids. Each molecule is made up of one glycerol molecule attached to two fatty acids and a phosphate group. Structurally, phospholipids are similar to triglycerides except that a phosphate group replaces one of the fatty acids. Phospho-lipid molecules have one end that is attracted to water while the other is repelled by it. This property is important in plasma membranes. The fatty acid end that is not attracted to water is said to be hydrophobic. At the other end of the molecule, the phosphate group that is attracted to water is said to be hydrophilic. Three major types of body phospholipids: 1. The lecithins: are a group of phospholipids that upon hydrolysis yield two fatty acid molecules and a molecule each of glycerol, phosphoric acid, and choline. They are water soluble emulsifiers and membrane constituents. 2. The cephalins: are a group of phospholipids having hemostatic properties and found especially in the nervous tissue of the brain and spinal cord. The cephalins resemble lecithin, except they contain either 2-ethanolamine or L-serine in the place of choline. 3. The sphingomyelins: are a group of phospholipids that are found especially in nerve tissue and yield sphingosine, choline, a fatty acid, and phosphoric acid upon hydrolysis. They are membrane constituents. Note: The neurologic disturbances seen in Niemann-Pick disease are associated with the accumulation in CNS tissue of sphingomyelin.

Cortisol is the primary glucocorticoid produced by the adrenal cortex gland:\ Cortisol's principal physiological actions include all of the following EXCEPT one. Which one is the EXCEPTION? • Increase hepatic gluconeogenesis • Increase hepatic glycogenolysis • Increase protein catabolism • Stimulation of fat deposition and inhibition of lipolysis • Inhibit ACTH secretion (negative feedback mechanism) • Maintenance of blood pressure by sensitizing arterioles to the action of noradrenaline • Renal excretion

Stimulation of fat deposition and inhibition of lipolysis *** This is false; glucocorticoids (mainly, cortisol) promote mobilization of fatty acids from adipose tissue and stimulate lipolysis. Remember: Cushing's syndrome is a metabolic disorder resulting from the chronic and excessive production of cortisol. The most common cause of this syndrome is a pituitary tumor that causes an increased secretion of ACTH.

The secretions of which two glands includes a substance that contains many glycoproteins and functions to lubricate food and the mouth? • Parotid • Submandibular • Sublingual

Submandibular Sublingual The basic secretory units of salivary glands are clusters of cells called acini. These cells secrete a fluid (pH between 6.0 and 7.0) that contains water, electrolytes, mucus, and enzymes, all of which flow out of the acinus into collecting ducts. Three major pairs of salivary glands that differ in the type of secretion they produce: • Parotid glands produce a serous, watery secretion. • Submandibular glands produce a mixed serous and mucous secretion. • Sublingual glands secrete a saliva that is predominantly mucous in character. Two Secretions: 1. Mucous secretion: contains mucins (glycoproteins), which are proteins that have polysaccharides attached to them. Lubricates the mouth and food. 2. Serous secretion: contains the enzyme salivary amylase (ptyalin). This enzyme splits starch into alpha-dextrin, maltotriase, and maltose. A number of proteins (proline-rich proteins, statherin, etc.) play important roles in maintaining the enamel surface and preventing calculus formation. The secretion of saliva is under control of the autonomic nervous system, which controls both the volume and type of saliva secreted. Both parasympathetic and sympathetic stimulations cause secretion, with parasympathetic having the greatest effect. Note: Vagal stimulation increases saliva production, so vagotomy (or atropine) inhibits saliva production and produces dry mouth. *** Atropine prevents the action of acetylcholine on the secreting cells. Remember: Before swallowing can be initiated, afferent information must be received from mucosal mechanoreceptors, indicating the consistency of a soft bolus of food.

Which of the following is not found in the thyroid? • TSH • T3 • TRH • T4 • Tyrosine

TRH Thyrotropin-releasing hormone (TRH) is a hormone released by the hypothalamus that communicates with the pituitary gland and stimulates release of thyroid-stimulating hor-mone. Thyroglobulin contains iodine, which is attached to tyrosine molecules. The follicle cells of the thyroid gland synthesize thyroglobulin and secrete it into the colloid-containing regions of the follicles. Here the thyroglobulin undergoes iodination and coupling processes that produce the thyroid hormones, thyroxine (7'4) and triiodothyronine (7'3). The thyroglobulin molecules containing these hormones are then stored in the colloid-containing regions of the follicles. When the thyroid is actively secreting, these thyroglobulin molecules are then taken back into the follicle cells and broken down into the two hormones, thyroxine (7'4) and triiodothyronine (T3). Note: Normally, T4 concentration in the blood is approximately 20-fold greater than the concentration of T3. However, T3 is approximately five times more physiologically potent than T4, and can be formed by removing one iodine atom from T4. These hormones (mostly thyroxine) enter the bloodstream and produce the following actions: • Important for normal growth and development (especially the brain) • Affect many metabolic processes and the metabolic rate • Increase oxygen consumption and heat production Note: A dietary iodine deficiency will increase the secretion of thyroglobulin (as opposed to thyroxine, triiodothyronine, or TSH).

Hormones of Major Endocrine Glands Hormones Source Endocrine Target Action

Testosterone Estrogen Progesterone Human chorionic gonadotropin (hCG) Testis Ovarian follicles Corpus luteum Chorion (fetal tissue component of the placenta) Spermatogenic cells Muscle Bone tissue Other tissues Uterus Mammary glands Other tissues Uterus Other tissues Ovary Spermatogenesis; male secondary sex characteristics Growth and development of female reproductive organs Follicular phase of menstrual cycle Maintains (along with estrogen) the lining of the uterus necessary for successful pregnancy Increases estrogen and progesterone synthesis by the corpus luteum

All of the following statements concerning the citric acid cycle (Krebs cyc-)e) are true EXCEPT one. Which one is the EXCEPTION? • It is also called the tricarboxylic acid (TCA) cycle • The cycle starts with the 4-carbon compound oxaloacetate, adds 2 carbons from acetyl-CoA, loses 2 carbons as CO2, and regenerates the 4-carbon compound oxaloacetate • The pyruvate that enters this cycle is generated by the glycolysis of glucose or protein catabolism • This cycle is controlled by regulation of several enzyme activities. The most important of these regulated enzymes are citrate synthase, isocitrate dehydrogenase, and a¬ketoglutarate dehydrogenase complex • The enzymes involved in the citric acid cycle are found in the cytosol

The enzymes involved in the citric acid cycle are found in the Cytosol *** This is false; the enzymes involved in this cycle are found in the mitochondria. After glycolysis takes place in the cell's cytoplasm, the pyruvic acid molecules travel into the interior of the mito¬chondrion. Once the pyruvic acid is inside, carbon dioxide is enzymatically removed from each three-carbon pyru¬vic acid molecule to form acetic acid. The enzyme then combines the acetic acid with an enzyme, coenzyme A, to produce acetyl coenzyme A, also known as acetyl-CoA. Once acetyl- CoA is formed, the Krebs cycle begins. The cycle is split into eight steps: 1. The acetic acid subunit of acetyl-CoA is combined with oxaloacetate to form a molecule of citrate. The acetyl ¬coenzyme A acts only as a transporter of acetic acid from one enzyme to another. After Step 1, the coenzyme is re¬leased by hydrolysis so that it may combine with another acetic acid molecule to begin the Krebs cycle again. 2. The citric acid molecule undergoes isomerization. A hydroxyl group and a hydrogen molecule are removed from the citrate structure in the form of water. The two carbons form a double bond until the water molecule is added back. Only now, the hydroxyl group and hydrogen molecule are reversed with respect to the original structure of the citrate molecule. Thus, isocitrate is formed. 3. In this step, the isocitrate molecule is oxidized by a NAD molecule. The NAD molecule is reduced by the hy¬drogen atom and the hydroxyl group. The NAD binds with a hydrogen atom and carries off the other hydrogen atom, leaving a carbonyl group. This structure is very unstable, so a molecule of CO2 is released, creating alpha¬ketoglutarate. 4. In this step, our friend, coenzyme A, returns to oxidize the alpha-ketoglutarate molecule. A molecule of NAD is reduced again to form NADH and leaves with another hydrogen. This instability causes a carbonyl group to be re¬leased as carbon dioxide, and a thioester bond is formed in its place between the former alpha-ketoglutarate and coenzyme A to create a molecule of succinyl-coenzyme A complex. 5. A water molecule sheds its hydrogen atoms to coenzyme A. Then, a free-floating phosphate group displaces coenzyme A and forms a bond with the succinyl complex. The phosphate is then transferred to a molecule of GDP to produce an energy molecule of GTP. It leaves behind a molecule of succinate. 6. In this step, succinate is oxidized by a molecule of FAD (flavin adenine dinucleotide). FAD removes two hydro¬gen atoms from the succinate and forces a double bond to form between the two carbon atoms, thus creating fu¬marate. 7. An enzyme adds water to the fumarate molecule to form malate. Malate is created by adding one hydrogen atom to a carbon atom and then adding a hydroxyl group to a carbon next to a terminal carbonyl group. 8. In this final step, the malate molecule is oxidized by a NAD molecule. The carbon that carried the hydroxyl group is now converted into a carbonyl group. The end product is oxaloacetate which can then combine with acetyl-coenzyme A and begin the Krebs cycle all over again.

Ovulation occurs as a result of: • The progesterone-induced LH surge • The estrogen-induced FSH surge • The progesterone-induced FSH surge • The estrogen-induced LH surge

The estrogen-induced LH surge Ovulation is the discharge of a mature ovum (oocyte) from the mature follicle (graafian follicle) of the ovary. Ovulations occurs as a result of the cyclic ovarian cycle and pituitary endocrine function. The anterior pituitary secretes the gonadotropins FSH and LH, with LH predominating. Remember: Late in the proliferative phase, estrogen levels peak, FSH secretion declines, and LH secretion increases, surging at mid-cycle (around day 14). Important point: The LH surge leads to final maturation of the follicle, rupture of the follicle, and ovulation. 1. Without LH, even though large quantities of FSH are available, the follicle will not progress to the stage of ovulation. 2. The ruptured mature follicle forms the corpus luteum, which secretes progesterone and estrogen. 3. FSH and LH are both glycoproteins and act in both the ovaries (in females) and the testes (in males). Two significant results of the female sexual cycle are: 1. Only a single mature ovum is normally released from the ovaries each month so that only a single fetus can begin to grow at a time. 2. The uterine endometrium is prepared for implantation of the fertilized ovum at the required time of the month.

Which one of the following statements about protein structure is correct? • Proteins consisting of one polypeptide can have quaternary structure • The formation of a disulfide bond in a protein requires that the two participating cysteine residues be adjacent to each other in the primary sequence of the protein • The stability of quaternary structure in proteins is mainly due to covalent bonds among the subunits • The information required for the correct folding of a protein is contained in the specific sequence of amino acids along the polypeptide chain

The information required for the correct folding of a protein is contained in the specific sequence of amino acids along the polypeptide chain *** The correct folding of a protein is guided by specific interactions among the side chains of the amino acid residues of a polypeptide chain. Proteins are polymers built from amino acids joined by peptide bonds. The resulting chain of amino acids (called a polypeptide) is then folded in different ways and to different extents. Generally, amino acids have a central or alpha carbon to which is attached a hydrogen atom (H), a carboxyl group (COOH), an amino group (NH2), and a fourth group that differs from one amino acid to another and is often indicated by the letter R. Approximately 20 different amino acids (they possess different R groups) are commonly found in proteins of the body. Proteins are formed from amino acids by reactions that bond the alpha amino group of one amino acid to the alpha carboxyl group of another. This bond is called a peptide bond. Two amino acids joined together by a peptide bond form a dipeptide. Ten or more amino acids linked in a chain by peptide bonds form a polypeptide chain. A protein is a polypeptide chain of approximately 100 or more amino acids linked by peptide bonds. The order of amino acids in a protein from the amino terminal to the carboxy terminal of the protein chain is referred to as the primary structure of the protein. Higher-order structures are dependent on the primary structure. 1. The two cysteine residues that react to form the disulfide bond may be a great distance apart in the primary structure but are brought into close proximity by the three-dimensional folding of the polypeptide chain. 2. Quaternary structure requires more than one polypeptide chain. These chains associate through noncovalent interactions.

( Caries activity is directly proportional to all of the following EXCEPT one. Which one is the EXCEPTION? j • The consistency of fermentable carbohydrates ingested • The quantity of fermentable carbohydrates ingested • The frequency of ingesting fermentable carbohydrates • The oral retention of fermentable carbohydrates ingested

The quantity of fermentable carbohydrates ingested There is abundant evidence that the initiation of caries requires a relatively high proportion of mutans streptococci within dental plaque. These bacteria adhere well to the tooth surface, produce higher amounts of acid from sugars than other bacterial types, can survive better than other bacteria in an acid environment, and produce extracellular polysaccharides from sucrose. Because they are more acid tolerant than other bacteria, acidic conditions within plaque favor the survival and reproduction of mutans streptococci. Two other types of bacteria are also associated with the progression of caries through dentin. These are several species of lactobacillus, and actinomyces viscosus. These bacteria are also highly acidogenic and survive well in acid conditions. Each time that plaque bacteria come into contact with food or drink containing simple sugars (monosaccharides such as glucose and fructose, and disaccharides such as sucrose, lactose and maltose), the plaque bacteria use the sugars for the bacteria's metabolic needs, making organic acids (i.e., lactic acid) a metabolic by-product. If these acids are not buffered by saliva, they dissolve the surface of the apatite crystals of adjacent tooth structure. This is called demineralization (this occurs when the pH level of the mouth drops below 5.5). Caries depends on the balance between demineralization and remineralization, i.e., on the frequency of eating (and on the microbial composition of the plaque and its chemical nature and thickness, on the local fluoride concentration, and on the buffering capacity of saliva). A frequent pattern of eating therefore increases caries risk. Extracellular dextrans are the structural component of plaque. They are formed from sucrose by bacterial enzymes (glycosyl transferases), which are located on the cell surface of certain lactic acid bacteria (e.g., S. mutans and lactobacilli). Dextrans are essential for the cariogenicity of these bacteria.

The factors that influence the rate of gas diffusion across the respiratory membrane include all of the following EXCEPT one. Which one is the EXCEPTION? • The thickness of the membrane • The surface area of the membrane • The temperature of the system • The diffusion coefficient of the gas in the substance of the membrane • The partial pressure difference of the gas between the two sides of the membrane

The temperature of the system The respiratory membranes of the lungs are in the respiratory bronchioles, alveolar ducts, and alveoli. Surrounding each alveolus is a network of capillaries arranged so that air within the alveoli is separated by a thin respiratory membrane from the blood contained within the alveolar capillaries. Factors That Influence the Rate of Gas Diffusion Across the Respiratory Membrane: • Thickness of the membrane: the rate of diffusion across the membrane is inversely proportional to the diffusion distance. • Surface area of the respiratory membrane: the rate of diffusion is directly proportion¬al to the surface area. Emphysema decreases the surface area, which impedes the exchange of gases. • The diffusion coefficient of the gas in the substance of the membrane: the diffusion coefficient is a measure of how easily a gas will diffuse through a liquid or tissue, taking into account the solubility of the gas in the liquid and the size of the gas molecule (molecular weight). Note: The solubility of CO2 is approximately 20 times greater than the solubility of 02. • The partial pressure difference of the gas between the two sides of the membrane: The partial pressure difference of a gas across the respiratory membrane is the difference between the partial pressure of the gas in the alveoli and the partial pressure of the gas in the blood of the alveolar capillaries. When the partial pressure of a gas is greater on one side of the respiratory membrane than on the other side, net diffusion occurs from the higher to the lower pressure. Normally, the partial pressure of oxygen (Po2) is greater in the alveoli than in the blood of the alveolar capillaries, and the partial pressure of carbon dioxide (Pco2) is greater in the blood than in the alveolar air. The partial pressure difference for oxygen and carbon dioxide can be increased by increasing the alveolar ventilation rate. The greater volume of atmospheric air exchanged with the residual volume raises alveolar Po2, lowers alveolar Pco2, and promotes gas exchange.

Which of the following statements concerning the two principal laws of thermodynamics is false? • They apply only to closed systems, that is, entities within which there can be no loss of energy or of mass • The first law says that the total quantity of energy in the universe remains constant (this is the principle of the conservation of energy) • The second law states that the quality of this energy is degraded irreversibly (this is the principle of the degradation of energy) • The second law, known as Carnot's principle, is controlled by the concept of entropy • The two laws describe the concept that Delta G is positive in an exergonic reaction

The two laws describe the concept that Delta G is positive in an exergonic reaction The principle energy laws that govern every organization are derived from the two famous laws of thermodynamics. Heat, being a form of energy, is subject to the principle of energy conservation; this principle is called the first law of thermodynamics -- The total energy, including heat, in a closed system is conserved. Heat, being a form of energy, can be transformed into work and other forms of energy, and vice versa. However, this transformation of heat energy is subject to a very important restriction, called the second law of thermodynamics. It can be given in three equivalent forms: 1. Heat flows spontaneously from a hot body to a cool one 2. One cannot convert heat completely into useful work 3. Every isolated system becomes disordered in time *** Entropy is a measure of the degree of randomness or disorder of a system. Certain chemical reactions proceed spontaneously until equilibrium is reached. Reactions that proceed with the release of energy are exergonic. Because the products of such reactions have less free energy than the reactants, the free-energy change (AG) is negative. Chemical reactions in which the products have more free energy than the reactants are endergonic. For these reactions, the AG is positive, and heat is consumed as a reactant.

An apprehensive dental patient comes in and states that he already ---"N took ibuprofen for the pain he anticipates from the appointment today. As you know, this inhibits the synthesis of prostaglandins. All of the following statements are true about prostaglandins EXCEPT one. Which one is the EXCEPTION? • They have a very short half-life • They generally act locally on or near the tissue that produced them • They are synthesized only in the liver and the adrenal cortex • The common precursor of prostaglandins is arachidonic acid (an unsaturated fatty acid) • Their synthesis can be inhibited by a number of unrelated compounds, including aspirin and cortisol

They are synthesized only in the liver and the adrenal cortex *** This is false; prostaglandins are synthesized by a broad variety of tissues. Prostaglandins are any of a group of components derived from unsaturated 20-carbon fatty acids, primarily arachidonic acid, via the cyclooxygenase pathway; prostaglandins are potent mediators of numerous different physiologic processes. Prostaglandins belong to a subclass of lipids known as the eicosanoids (along with thromboxanes and leukotrienes) because of their structural similarities to the C-20 polyunsaturated fatty acids, the eicosanoic acids. In general, prostaglandins act in a manner similar to that of hormones, by stimulating target cells into action. However, prostaglandins differ from hormones in they act locally, near their site of synthesis, and they are metabolized very rapidly. Also, the same prostaglandins act differently in different tissues. Prostaglandins are 20-carbon fatty acids that contain a five-carbon ring. Prostaglandins are synthesized in the cell from arachidonic acid created by phospholipase A2. The intermediate is then passed into one of either the cyclooxygenase or lipoxygenase pathways to form either prostaglandins and thromboxanes or leukotrienes. The cyclooxygenase pathway produces thromboxanes, prostacyclins, and prostaglandins D, E, and F. The lipoxygenase pathway is active in leukocytes and in macrophages and produces leukotrienes. Prostaglandins are released through the prostaglandin transporter on the cell's plasma membrane. 1. Prostaglandins seem to modulate the action of hormones rather than act as Notes hormones themselves. 2. Aspirin, indomethacin, ibuprofen, and phenylbutazone, which are NSAIDs, inhibit the biosynthesis of prostaglandins by interfering with the enzyme cyclooxygenase, the enzyme that initiates the formation of prostaglandins from arachidonic acid. 3.Prostaglandins enhance inflammatory effects, whereas aspirin diminishes them.

Which of the following is not a similarity between cytochromes and hemoglobins? • They both contain iron molecules • They both contain porphyrin rings • They both are found in the cytoplasm • They both are used by eukaryotes

They both are found in the cytoplasm *** Cytochromes are found in mitochondria and chloroplasts. Cytochromes are, in general, membrane-bound hemoproteins that contain heme groups and carry out electron transport. They are found either as monomeric proteins (e.g., cytochrome c) or as subunits of bigger enzymatic complexes that catalyze redox reactions. Cytochromes are found in the mitochondrial inner membrane and endoplasmic reticulum of eukaryotes, in the chloroplasts of plants, in photosynthetic microorganisms, and in bacteria. The electric transport chain is the final common pathway by which electrons derived from different fuels of the body flow to oxygen. Note: Electron transport and ATP synthesis by oxidative phosphorylation proceed continuously in all cells of the body that contain mitochondria. Cytochromes receive electrons from the reduced form of coenzyme Q (ubiquinone). Each contains a heme group made of a porphyrin ring containing an atom of iron. This cytochrome iron atom is the electron carrier and is reduced when the cytochrome accepts an electron (Fe3+ , Fe2+). Cytochromes are distinguished by differences in their light-absorption spectra and are designated b, cl, c, a3, and a. These differences are a result of the heme prosthetic group. Note: Cytochromes a3 and a are the terminal members of the electron transport chain. They exist as a complex, which is called Complex IV or cytochrome oxidase complex. Note: The prosthetic groups of cytochromes have four five-membered, nitrogen-containing rings in a cyclic structure called a porphyrin. The four nitrogen atoms are coordinated with a central Fe ion that can be either Fe+2 or Fe+3. Remember: These porphyrins are also found in the heme proteins hemoglobin and cytochrome P450. Glycine and succinyl-CoA are the precursors to the biosynthesis of these rings.

The countercurrent mechanism is a system in the renal that facilitates the of the urine. The system is responsible for the secretion of urine in response to plasma osmolarity. • Cortex / concentration / hyperosmotic / elevated • Medulla / dilution / hypo-osmotic / depressed • Cortex / dilution / hypo-osmotic / depressed • Medulla / concentration / hyperosmotic / elevated

medulla / concentration / hyperosmotic / elevated The countercurrent mechanism is a system in the renal medulla that facilitates concentration of the urine as it passes through the renal tubules. This mechanism is responsible for the secretion of hyperosmotic urine in response to elevated plasma osmolarity and requires the penetration of the loop of Henle into the renal medulla for the development of a medullary osmotic gradient. The mechanism depends on the special anatomical arrangement and transport properties of the loop of Henle. Important: The kidney dialysis machine is an example of a countercurrent mech¬anical system. The countercurrent multiplier in the loop of Henle is dependent upon the active reabsorption of sodium chloride by the thick ascending loop of Henle, the osmotic equilibrium between interstitial fluid and tubular fluid in the descending loop of Henle, and continued inflow of new sodium chloride from the proximal tubule into the loop of Henle. The sodium chloride reabsorbed from the ascending loop of Henle keeps adding to the newly arrived sodium chloride, thus "multiplying" its concentration in the medullary interstitium. Countercurrent exchange occurs in a region of the peritubular capillary bed called the "vasa recta." Important point: The vasa recta do not create the medullary hyperosmolarity but do prevent it from being dissipated and can carry away the water that has been reabsorbed.

Some coenzymes serving as transient carriers of specific atoms or functional groups Derived from Functions Thiamine pyrophosphate (TPP) Flavin adenine dinucleotide (FAD) Nicotinamide adenine dinu- cleotide (NAD) Coenzyme A Pyridoxal phosphate (PLP) Tetrahydrofolate Lipoate Coenzyme BI2

Thiamine (vitamin BI) Riboflavin (vitamin B2) Nicotinic acid (n ac n) Pantothenic acid (vitamin B3) Pyridoxine (vitamin Bo) Folic acid Not required in diet Vitamin Biz Vital to tissue respiration. Plays a role in the removal of carboxyl (-COOH) groups from organic acids, releasing the carbon and oxygen atoms as carbon dioxide (CO2). Functions in certain oxidation / reduction reactions in the body. Utilized alternately with NADH as an oxidizing or reducing agent in various metabolic processes. Functions as an acyl group carrier and is necessary for fatty acid synthesis and oxidation, pyruvate oxidation, and other acetylation reactions. Is essential for many enzymatic reactions, almost all of which are associated with amino acid metabolism. Participates in the transfer of various carbon fragments from one molecule to another; they are, for instance, involved in the synthesis of methionine and thymine. Cofactor for the pyruvate dehydrogenase complex, which breaks down pyruvate to form acetyl-CoA. Is an essential cofactor for several enzymes.

Which of the following functions as a coenzyme vital to tissue respiration? • Pyridoxal phosphate • Biocytin • Thiamine pyrophosphate • Tetrahydrofolate

Thiamine pyrophosphate Thiamine pyrophosphate functions as a coenzyme vital to tissue respiration. It is required as a cofactor for the enzyme pyruvate dehydrogenase, which catalyzes the oxidative decarboxylation of pyruvate, to form acetyl-CoA, which then enters into the Krebs cycle for the generation of energy. Thiamine pyrophosphate is also a coenzyme for transketolase, which functions in the pentose phosphate pathway, an alternate pathway for glucose oxidation.

Hormones of the Pituitary Target Gland Hormones Source Target Action(s)

Thyroid-stimulating hormone Follicle-stimulating hormone Luteinizing hormone Growth hormone Prolactin Adrenocorticotropic hormone Melanocyte- stimulating hormone Oxytocin Antidiuretic hormone (vasopressin) Anterior pituitary Anterior pituitary Anterior pituitary Anterior pituitary Anterior pituitary Anterior pituitary Anterior pituitary Posterior pituitary Posterior pituitary Thyroid gland Ovary Testis Ovary Testis Bone Mammary glands Adrenal cortex Skin Mammary glands Uterine smooth muscle Kidney tubules Stimulates synthesis and secretion of thyroid hormones Stimulates growth of graafian follicles and estrogen secretion Promotes sperm maturation (testis) Stimulates ovulation, formation of corpus luteum, and synthesis of estrogen and progesterone (ovary) Stimulates synthesis and secretion of testosterone (testis) Stimulates protein synthesis and overall growth Stimulates milk production and breast development Stimulates synthesis and secretion of adrenal cortical hormones Stimulates melanin synthesis Milk ejection Uterine contraction Stimulates water reabsorption by renal collecting ducts

Nerves connect with muscles at the . There, the ends of nerve fibers connect to special sites on the muscle's membrane called . These plates contain receptors that enable the muscle to respond to • Gap junction, motor end plates, norepinephrine • Mucocutaneous junction, visceral end plates, epinephrine • Neuromuscular junction, motor end plates, acetylcholine • Neuromuscular junction, sensory end plates, norepinephrine

neuromuscular junction, motor end plates, acetylcholine Acetylcholine is released by the nerve to transmit a nerve impulse across the neuromus¬cular junction. After a nerve stimulates a muscle at this junction, an electrical impulse flows through the muscle, causing it to contract. Acetylcholine (ACh) is the neurotransmitter released from the presynaptic terminal, and the postsynaptic membrane contains a nicotinic receptor. ACh is synthesized in the neurons from which it is released. Choline acetyltransferase catalyzes the formation of acetylcholine from acetyl-CoA and choline in the presynaptic terminal. The terminals of motor axons contain thousands of synaptic (storage) vesicles filled with acetylcholine. The action potential conducted along the motor nerve causes depolarization and an influx of calcium. The influx of calcium stimulates the release of ACh from storage vesicles into the synapse. ACh binds to nicotinic receptors on the motor end plate. Stimulation of the ACh receptor results in the opening of sodium channels (and some potassium channels), and an influx of sodium and potassium into the cell that results in depolarization. Depolarization is termed "end-plate potential" (EPP). If the EPP is sufficiently large, an action potential is produced, muscle contraction occurs, and ACh is metabolized by acetylcholinesterase. Important: Following its release from the presynaptic terminal, ACh is rapidly broken down into acetate and choline by the enzyme acetylcholinesterase (ACNE) on the motor end-plate. Note: If acetylcholinesterase is inhibited, there will be prolongation of the end-plate potential (EPP), which can lead to tetanus of the affected muscle fibers. Note: The neuromuscular junction (NMJ) is the synapse between the presynaptic motor neuron and the postsynaptic muscle membrane.

Which of the following parameters is decreased during exercise? • Heart rate (HR) • Cardiac output (CO) • Total peripheral resistance (TPR) • Stroke volume (SV) • Arterial pressure

Total peripheral resistance (TPR) *** This is caused by the accumulation of vasodilator metabolites (lactate, potassium ions, and adenosine). These metabolites accumulate because of an increasing metabolic rate within the exercising muscle. This arterial vasodilation accounts for the overall decrease in TPR. Three major effects are essential for the circulatory system to supply the tremendous blood flow to the muscles during exercise: 1. Mass discharge of the sympathetic nervous system throughout the body with consequent stimulative effects on the circulation. 2. Increase in cardiac output. 3. Increase in arterial pressure. During exercise, the dilation of blood vessels in active skeletal muscles greatly increases blood flow to the muscles. At the same time, sympathetic vasoconstrictor activity causes a compensatory constriction of vessels elsewhere in the body. There is also an increase in the activity of the sympathetic nerves to the heart and a decrease in the activity of the parasympathetic nerves. In addition, venous return is enhanced by the increased pumping effects of the contracting skeletal muscles and by the sympathetic vasoconstrictor effects. As a result, both heart rate and stroke volume increase, causing an increase in cardiac output. During exercise, the increase in cardiac output is somewhat greater than the decrease in total peripheral resistance. Therefore, the mean arterial pressure rises. Important: An anxious dental patient may have a higher systolic blood pressure than previously noted; this is most likely due to decreased arterial compliance.

Term, give the Meaning: Apnea Hypercapnea Hypocapnea Hyperapnea Respiratory arrest Hyperventilation Hypoventilation Dyspnea

Transient cessation or absence of breathing Excess CO2 in arterial blood Below normal CO2 in arterial blood Abnormally deep and rapid breathing Permanent cessation of breathing (unless corrected) Increased pulmonary ventilation in excess of metabolic requirements Underventilation in relation to metabolic requirements Unpleasant sensation of difficulty of breathing

Which of the following valves is located between the right atrium and right ventricle? • Mitral valve • Tricuspid valve • Pulmonary semilunar valve • Aortic semilunar valve ( Which valve is unique in having a different number of cusps than the others? ) • Mitral valve • Tricuspid valve • Pulmonary semilunar valve • Aortic semilunar valve

Tricuspid valve Mitral valve (bicuspid valve) The heart consists of four chambers: two atria (upper chambers) and two ventricles (lower chambers). There is a valve through which blood passes before leaving each chamber of the heart. The valves prevent the backward flow of blood. These valves are actual flaps that are located on each end of the two ventricles (lower chambers of the heart). They act as one way inlets of blood on one side of a ventricle and one-way outlets of blood on the other side of a ventricle. The atrioventricular valves are tough, fibrous flaps of endocardium. Both are secured to papillary muscles of the ventricular walls by chordae tendineae. • The tricuspid valve is located between the right atrium and right ventricle, surrounding the AV orifice. The tricuspid valve is composed of three cusps that prevent a backflow of blood from the right ventricle into the right atrium during ventricular contraction. • The mitral (bicuspid) valve is located between the left atrium and the left ventricle, surrounding the AV orifice. The mitral valve is composed of two cusps that prevent a backflow of blood from the left ventricle to the left atrium during ventricular contraction. Note: These valves are open during ventricular diastole, but they are forced shut as the pressure in the ventricles increases, thus preventing the flow of blood back into the atria while the ventricles are contracting. The pulmonary semilunar valve is located at the entrance to the pulmonary trunk. It is composed of three cusps that prevent the backflow of blood from the pulmonary artery into the right ventricle during ventricular relaxation. The aortic semilunar valve is located at the entrance to the ascending aorta. It is composed of three cusps that prevent a backflow of blood from the aorta into the left ventricle during ventricular relaxation. These valves are open during ventricular systole. Important: At no time during the cardiac cycle are all the valves of the heart open at the same time.

Hormones of the Thyroid and Parathyroid Glands Hormone Source Target Action(s)

Triiodothyronine (r3) Tettaiodothyronine or thyroxine (T4) Calcitonin Parathyroid hor- mono (PTH) Thyroid gland (follicular cells) Thyroid gland (follicular cells) Thyroid gland (parafollicular cells) Parathyroid glands General General Bone tissue Kidneys Bone tissue Intestinal tract Increases rate of metabolism Increases rate of metabolism (usually converted to T3 first) Increase calcium storage in bone, lowering blood Ca++ levels Increases calcium removal from storage in bone and increases absorption of calcium by intestines, increas-ing blood Ca ++ levels

Spatial summation occurs when: • Two inhibitory inputs arrive at a postsynaptic neuron within 1 minute of each other • Two excitatory inputs arrive at a postsynaptic neuron simultaneously • Two inhibitory inputs arrive at a postsynaptic neuron 10 seconds apart • Two excitatory inputs arrive at a postsynaptic neuron in rapid succession

Two excitatory inputs arrive at a postsynaptic neuron simultaneously Neurotransmitters may be excitatory, increasing the probability of causing an action potential in the postsynaptic neuron (an excitatory postsynaptic potential or EPSP), or inhibitory, decreasing the probability of an action potential in the postsynaptic neuron (an inhibitory postsynaptic potential or IPSP). Note: Neurotransmitter molecules may have excitatory or inhibitory effects depending upon their binding to different subtypes of receptors. There are two forms of summation by which EPSPs may combine to reach threshold and initiate an action potential: 1. Spatial summation occurs when two excitatory inputs arrive at a postsynaptic neuron simultaneously. It is the result of a converging circuit and is dependent upon the simultaneous arrival of impulses from multiple presynaptic fibers. 2. Temporal summation occurs when two excitatory inputs arrive at a postsynap¬tic neuron in rapid succession. In temporal summation, there is an increase in the frequency of nerve impulses in a single presynaptic fiber. Note: An action potential initiated at the midpoint along the length of an axon will spread toward the cell body (soma) and nerve ending.

Type of Vessel a) Arteries b) Veins c) Capillaries 1) Tunica Intima (Endothelium) 2) Tunic Media (Smooth Muscle; Elastic Connective Tissue) 3) Tunic Adventitia (Fibrous Connective Tissue)

1) a) Smooth lining b) Smooth lining with se- milunar valves to ensure one-way flow c) Makes up entire wall of capillary; thinness per¬mits ease of transport across vessel wall 2) a) Allows constriction and dilation of vessels; thicker than in veins; mus- cle innervated by autonomic fibers b) Allows constriction and dilation of vessels; thinner than in arteries; muscle innervated by autonomic fibers c) Absent 3)a) Provides flexible support that resists collapse or injury; thicker than in veins; thinner than tunica media b) Provides flexible support that resists collapse or injury; thinner than tunica media c) Absent

Jay Sack is a pediatric patient of yours. At a young age, he was diagnosed with Tay-Sachs disease. He has severe mental and motor deterioration, and your treat- ment is minimal as he is expected to die by age 5. His neurologic symptoms are due to the accumulation of the GM2 ganglioside. This is caused by: • A deficiency of a lysosomal enzyme that degrades gangliosides • Increased synthesis of the ganglioside precursor, ceramide • A genetic deficiency of phospholipase A2 • An increased concentration of the UDP-sugars required for ganglioside synthesis

A deficiency of a lysosomal enzyme that degrades gangliosides Lipid storage diseases, or the lipidoses, are a group of inherited metabolic disorders in which harmful amounts of fatty materials called lipids accumulate in some of the body's cells and tissues. People with these disorders either do not produce enough of one of the enzymes needed to metabolize lipids, or the individuals produce enzymes that do not work properly. Over time, this excessive storage of fats can cause permanent cellular and tissue damage, particularly in the brain, peripheral nervous system, liver, spleen, and bone marrow. • Gaucher disease is the most common of the lipid storage diseases. It is caused by a deficiency of the enzyme glucocerebrosidase. Fatty material can collect in the spleen, liver, kidneys, lungs, brain, and bone marrow. Symptoms may include enlarged spleen and liver, liver malfunction, skeletal dis¬orders, and bone lesions that may cause pain, severe neurologic complications, swelling of lymph nodes, and (occasionally) adjacent joints, distended abdomen, a brownish tint to the skin, anemia, low blood platelets, and yellow spots in the eyes. This disorder is particularly frequent in families of Ashke¬nazi (central-eastern Europe) Jewish ancestry. • Niemann-Pick disease is actually a group of autosomal recessive disorders caused by an accumu-lation of fat and cholesterol in cells of the liver, spleen, bone marrow, lungs, and, in some patients, brain. Neurological complications may include ataxia, eye paralysis, brain degeneration, learning problems, spasticity, feeding and swallowing difficulties, slurred speech, loss of muscle tone, hyper-sensitivity to touch, and some corneal clouding. The disease results from the deficiency of the enzyme sphingomyelinase, which results in the accumulation of sphingomyelin. The disease is more common in those of Ashkenazi Jewish ancestry. • Tay-Sachs disease is a rare inherited disorder that causes progressive destruction of nerve cells in the brain and spinal cord (the central nervous system). The disease is caused by a deficiency of the enzyme beta - hexosaminidase A which results in the accumulation of GM2 gangliosides, especially in neurons. The disease occurs primarily in families of Ashkenazi Jewish ancestry. It is characterized by CNS degeneration with severe mental and motor deterioration. Death usually occurs by age 5. • Krabbe disease is an autosomal recessive disorder caused by deficiency of the enzyme galactosyl-ceramidase. • Fabry disease, also known as alpha-galactosidase-A deficiency, causes a buildup of fatty material in the autonomic nervous system, eyes, kidneys, and cardiovascular system.

Properties of Vessels Arteries Arterioles Capillaries Veins

Largest pressure Largest resistance Largest cross-sectional area Largest blood volume

Characteristic of Skeletal Muscle Fibers in Slow Twitch (Type I) and Fast Twitch (Type II): Myosin-ATPase activity Speed / Intensity of contraction Resistance to fatigue Oxidative capacity Enzymes for anaerobic glycolysis Mitochondria Sarcoplasmic reticulum Capillaries Myoglobin content Glycogen content

Slow twitch: Low Slow / Low High High Low Many Less extensive Many High Low Fast twitch: High Fast / High Low Low High Few More extensive Few Low High

Zymogens Site of Synthesis Active Enzyme Pepsinogen Chymotrypsinogen Trypsinogen Procarboxypeptidase A Procarboxypeptidase B Proelastase

Stomach Pancreas Pancreas Pancreas Pancreas Pancreas Pepsin Chymotrypsin Trypsin Carboxypeptidase A Carboxypeptidase B Elastase

Lobes of the Cerebrum Frontal Temporal Parietal Occipital

Contains the primary motor (movement) area and influences personality, judgment, abstract reasoning, social behavior, and language expression. Controls hearing, language comprehension, storage and recall of memories. Interprets and integrates sensation, including pain, tempera¬ture, and touch; interprets size, shape, distance, and texture; important for awareness of body shape. Functions mainly to interpret visual stimuli.

on the medical history form, your patient answers yes to all of the following-\ symptoms. Your patient are most likely suffering from what condition? • Feel nervous, moody, weak, or tired • Have hand tremors, or have a fast or irregular heartbeat, or have trouble breathing even when you are resting • Sweat a lot, and have warm, red skin that may be itchy • Have frequent and sometimes loose bowel movements • Have fine, soft hair that is falling out • Lose weight even though you are eating normally or more than usual

Hyperthyroidism Excessive production of the thyroid hormone thyroxine produces the symptoms of hyperthyroidism. The primary role of thyroxine is to stimulate cellular metabolism, growth, and differentiation of all tissues. In excess, therefore, thyroxine leads to high basal metabolism, fatigue, weight loss, excitability, elevated temperature, and generalized osteoporosis. People with Graves' disease (the most common form of hyperthyroidism) often have ad¬ditional symptoms, including the following: • Goiter, which is an enlarged, painless, soft thyroid gland • Thickened nails that lift off the nail beds • Myxedema, which is lumpy, reddish, thick skin on the front of the shins and some¬times on top of the feet • Clubbing (fingers with wide tips) • Exophthalmos (bulging eyes) 1. Oral manifestations are not too remarkable, but if the disturbance begins in the early years of life, premature eruption of the teeth and loss of the deciduous dentition are common findings. 2. Plummer's disease (also called Parry's disease) is the cause of about 5% of cases of hyperthyroidism. This results from the presence of many toxic thyroid nodules within the thyroid gland. Exophthalmos is rare. 3. The symptoms of hypothyroidism include weight gain, cold intolerance, decreased cardiac output, hypoventilation, drooping eyelids, lowered pitch of voice, mental and physical slowness, constipation, dry skin, coarse hair, and puffiness of the face, eyelids, and hands.

It's 4 o'clock on a Friday afternoon, and you are about to do a quick preparation and restoration. When you give the injection, the patient complains of severe discomfort. You realize you forgot to aspirate the needle first, and you have just injected into an artery 1. Your needle passed through the artery layers in which order? • Tunica adventitia, tunica media, tunica intima • Tunica media, tunica intima, tunica adventitia • Tunica intima, tunica media, tunica adventitia • Tunica adventitia, tunica intima, tunica media 2. Judging by their relative thicknesses, which is the toughest vessel to puncture? • Artery • Vein • Capillary 3. Which layer is thicker: tunica media or tunica adventitia? 4. Which layer is innervated by the autonomic nervous system? • Tunica intima • Tunica media • Tunica adventitia 5. By puncturing this artery, you have hit the vessel with the greatest: • Resistance • Pressure • Cross-sectional area • Blood volume

1. Tunica adventitia, tunica media, tunica intima 2. Artery 3. Tunica media 4. Tunica media 5. Pressure

Normal range for hemoglobin is different between the sexes and is approximately for men and for women. • 5-8 grams per deciliter , 2-3 grams per deciliter • 9-11 grams per deciliter , 7-9 grams per deciliter • 13-18 grams per deciliter , 12-16 grams per deciliter • 20-22 grams per deciliter , 18-21 grams per deciliter

13-18 grams per deciliter , 12-16 grams per deciliter Hemoglobin a quaternary protein consisting of four tertiary (folded) polypeptide chains ¬-- two alpha chains and two beta chains. Each chain has an associated iron-containing heme group. Oxygen can bind to the iron of the heme group, or carbon dioxide can bind to amine groups of the amino acids in the polypeptide chains. Hemoglobin is essential to the ability of erythrocytes to transport oxygen and carbon dioxide, and a single erythrocyte contains up to 300 million hemoglobin molecules. Important point: Each hemoglobin molecule contains four iron atoms. Each atom binds one diatomic oxygen molecule for a maximum capacity of eight oxygen atoms per hemoglobin molecule. Normal Blood Values of Hemoglobin (* 100 ml = 1 dl) • Women: 12 to 16 grams per deciliter • Men: 13 to 18 grams per deciliter • Newborn: 14 to 20 grams per deciliter Important: • The Hgb value depends on the number of RBCc and the amount of Hgb in each RBC. • A low Hgb value is found in anemia, in hyperthyroidism and in cirrhosis of the liver. • A high Hgb value is found in polycythemia, in COPD, and in congestive heart failure. ' 1. Hemoglobin carries oxygen to tissue from the lungs and carbon dioxide Notesaway from tissue to the lungs. 2. Blood leaving the lungs is 98% saturated with oxygen. However, the hemoglobin of normal venous blood returning to the lungs is only 75% saturated. 3.Carbaminohemoglobin is hemoglobin that is carrying carbon dioxide from the tissues to the lungs. Whereas about 97% of the oxygen is transported by hemoglobin, only about 30% of the carbon dioxide is carried by hemoglobin; the rest is transported as bicarbonate or as carbon dioxide.

I sequence of DNA reads "A-T-G-C-A." How many hydrogen bonds would._. you expect to see holding this sequence to its complementary strand? • 12 • 14 • 16 • 18

14 (2 in each /1-T pairing and 3 in each G-C pairing) The two antiparallel polynucleotide chains of double-helical DNA are not identical in either base sequence or composition. Instead, they are complementary to each other. Wherever adenine appears in one chain, thymine is found in the other; similarly, wherever guanine is found in one chain, cytosine is found in the other. Important point: The actuality that separated DNA strands are able to reassociate represents the consequence of the fact that DNA strands are complementary. Note: Watson and Crick deduced this specificity of base pairing because of stearic and hydrogen-bonding factors. In the Watson-Crick structure, the two chains or strands of the helix are antiparallel, such that one strand runs 5' to 3' ("five prime to three prime") while the other runs 3' to 5'. The DNA double helix is held together by two sets of forces: hydrogen bonding between complementary base pairs and base-stacking interactions. The helix structure results in a major and a minor groove being formed along the DNA molecule. The major groove is the binding region for many proteins that control the transcriptional activity of the DNA molecule. Important: Three hydrogen bonds can form between G and C, but only two can form between A and T. The weaker bonding between A and T (or U in RNA) is used in transcription to aid in the release of the newly formed RNA from the DNA template.

Cell type- Part of Stomach -Secretion products -Stimulus for Secretion for the following: Parietal cells (Oxyntic) Chief cells (Zymogenic) G cells (Enteroendocrine cells) Mucous cells

Body (fundus) Body (fundus) Antrum Antrum HCL Intrinsic factor (essential) Pepsinogen (converted to pepsin at low pH) Gastrin Mucus Pepsinogen • Gastrin • Vagal stimulation (ACh) • Histamine • Vagal stimulation (ACh) • Vagal stimulation (via GRP) • Protein • Vagal stimulation (ACh)

The amount of oxygen bound to hemoglobin: • Increases if DPG concentration increases • Is constant between Po2s of 40 mmHg and 100 mmHg • Decreases if the Pco2 increases • Is directly proportional to the partial pressure of 02 • Increases if the temperature increases

Decreases if the Pco2 increases - Bohr effect Hemoglobin is the oxygen-bearing protein of red blood cells and constitutes about 33% of the cell weight. Oxygen is picked up in the blood (from the lungs) and forms oxyhemoglobin (Hb02); blood leaving the lungs is saturated with oxygen and carries oxygen to the tissues with decreased oxygen pressure; oxygen splits away from the hemoglobin and creates reduced hemoglobin (HHb). The combination of hemoglobin (Hb) with oxygen (02) is reversible, and whether Hb binds with or releases 02 depends in large part on the oxygen partial pressure (Po2). When the Po2 is relatively high, (as in the pulmonary capillaries), Hb has a higher affinity for 02 and is 98% saturated. At a lower Po2, (as in the tissue capillaries), Hb has a lower affinity for 02 and is only partially saturated. The partial pressure of 02 (pp0 2)is a factor in determing the amount of 02 bound to Hb; however there is no direct proportionality to the pp02. The ppCO2, pH, temperature, and DPG levels supersede the ppO2's influence. The following situations also promote the release of oxygen from oxyhemoglobin: (*** Oxygen dissociation curve shifts to the right) • Increase in diphosphoglycerate (DPG) • Increase in tissue temperature - exercise, physical activity • Decreased pH - increased arterial H+ ion concentration

Newborns with phenylketonuria: • Have mental retardation • Have stunted growth • Have seizures, tremors, or jerking movements in the arms and legs • Don't have any symptoms

Don't have any symptoms *** Newborns with phenylketonuria don't have any symptoms. Without treatment, though, babies usually develop signs of PKU within a few months. 1. Phenylalanine and tyrosine are both essential amino acids. 2. Tyrosine is produced by hydroxylation of the essential amino acid phenylalanine. 3. In phenylketonuria, tyrosine cannot be synthesized in adequate amounts and is required in the diet.

For each of the following, tell whether it will SLOW or SPEED up gastric emptying: • Gastric inhibitory peptide • Activation of the sympathetic nervous system • Activation of the parasympathetic nervous system • Secretin • Activation of the enteric nervous system • Cholecystokinin • Ingestion of food and its presence in the stomach

Gastric inhibitory peptide ... Slow Activation of the sympathetic nervous system ... Slow Activation of the parasympathetic nervous system ... Speed up Secretin Slow Activation of the enteric nervous system ... Slow Cholecystokinin ... Slow Ingestion of food and its presence in the stomach ... Speed up Foodstuffs entering the duodenum, especially fats and acidic chyme, stimulate the release of hormones, including cholecystokinin, secretin, and gastric inhibitory peptide (GIP), that inhibit the pyloric pump. Note: Stomach emptying is enhanced by the presence of food in the stomach and gastrin. The small intestine sends inhibitory signals to the stomach to slow secretion and motility. Two types of signals are used: nervous and endocrine. Distension of the small intestine, as well as chemical and osmotic irritation of the mucosa, is transduced into gastric inhibitory impulses in the enteric nervous system. This nervous pathway is called the enterogastric reflex. Secondly, enteric hormones such as cholecystokinin and secretin are released from cells in the small intestine and contribute to suppression of gastric activity. Remember: In general, sympathetic stimulation causes inhibition of gastrointestinal secretion and motor activity, and contraction of gastrointestinal sphincters and blood vessels. Conversely, parasympathetic stimuli and acetylcholine typically stimulate these digestive activities. They are two major types of contractions in the GI tract, peristalsis and mixing (segmentation) contractions. Peristaltic contractions generate propulsive movements. Mixing contractions serve to spread out the foodstuffs and increase the surface area available for digestion and absorption.

Which of the following glycosaminoglycans can be found functioning in synovial fluid? • Heparin sulfate • Keratan sulfate • Hyaluronic acid • Dermatan sulfate • Chondroitin sulfate

Hyaluronic acid The most abundant heteropolysaccharides in the body are the glycosaminoglycans (GAGs). These molecules are long unbranched polysaccharides containing a repeating disaccharide unit. The disaccharide units contain either of two modified sugars N-acetyl-galactosamine (GalNAc) or N-acetyl-glucosamine (GlcNAc) and a uronic acid such as glucuronate or iduronate. GAGs are highly negatively charged molecules, with extended conformation that imparts high viscosity to the solution. GAGs are located primarily on the surface of cells or in the extracellular matrix (ECM). Along with the high viscosity of GAGs comes low compressibility, which makes these molecules ideal for a lubricating fluid in the joints. At the same time, their rigidity provides structural integrity to cells and provides passageways between cells, allowing for cell migration. The specific GAGs of physiological significance are hyaluronic acid, dermatan sulfate, chondroitin sulfate, heparin, heparin sulfate, and keratan sulfate.

Reflex-Number of Synapses-Stimulus-Afferent Fibers Response Stretch reflex (knee jerk) Golgi tendon reflex (clasp knife) Flexor-withdrawal reflex (after touch- ing a hot stove)

Monosynaptic Disynaptic Polysynaptic Muscle is stretched Muscle contracts Pain Ia Ib II, 111, and IV Contraction of the muscle Relaxation of the muscle Ipsilateral flexion, contralateral extension

Within the spinal cord, the H-shaped mass of gray matter is divided into horns, which consist mainly of neuron cell bodies. Cell bodies in the posterior (dorsal) horn relay: • Voluntary motor impulses • Reflex motor impulses • Sensory impulses • All of the above

Sensory impulses *** This dorsal horn is also referred to as the dorsal root ganglia. Those cell bodies in the anterior (ventral) horn (root) transmit motor impulses. The white matter surrounding these horns consists of myelinated nerve fibers, which form the ascending and descending tracts. A tract represents a group of axons within the central nervous system having the same origin, termination, and function, and is often named for its origin and termination (i.e., spinothalamic tract). Axons of cells that run on the same side as their cell bodies of origin are referred to as ipsilateral. Axons of cells that run on the opposite side of their cell bodies of origin are referred to as contralateral. Note: Sensory pathways are ascending systems (i.e., spinothalamic and DC-ML systems); motor pathways are descending systems (i.e., pyramidal and extrapyramidal systems). Remember: The white matter refers to those parts of the brain and spinal cord that are responsible for communication between the various gray matter regions and between the grey matter and the rest of the body. In essence, the gray matter is where the processing is done and the white matter is the channels of communication. By analogy, the gray matter is like the CPU in a computer, and the white matter is like the printed circuit board that connects it to the other parts of the computer. White Matter vs. Gray Matter -- Both the spinal cord and the brain consist of: • White Matter = bundles of axons each coated with a sheath of myelin • Gray Matter = masses of the cell bodies and dendrites, each covered with synapses In the spinal cord, the white matter is at the surface, and the gray matter inside. In the brain of mammals, this pattern is reversed.

Characteristics of GAGs (Glycosaminoglycans) Localization and Comments Hyaluronate Chondroitin sulfate Heparin sulfate Heparin Dermatan sulfate Keratin sulfate

Synovial fluid, vitreous humor, ECM of loose connective tissue Cartilage, bone, heart valves Basement membranes, components of cell surfaces Component of intracellular granules of mast cells lining the arteries of the lungs, liver, and skin Skin, blood vessels, heart valves Cornea, bone, cartilage aggregated with chondroitin sulfates Large polymers, shock absorbing Most abundant GAG Contains higher acetylated glucosamine than heparin Serves as an anticoagulant, more sulfated than heparin sulfate Most heterogenous GAG

A patient walks into your office with yellow discoloration of the skin, sclera, and tissues. You immediately can infer that: • The patient has jaundice caused by hyperbilirubinemia • The patient has jaundice caused by hypobilirubinemia • The patient has diabetes insipidus caused by high levels of ADH • The patient has diabetes insipidus caused by low levels of ADH

The patient has jaundice caused by hyperbilirubinemia Jaundice is a yellowish discoloration of the skin and of the whites of the eyes caused by abnormally high levels of the pigment bilirubin in the bloodstream. Jaundice is very common and is the leading manifestation of liver disease. Jaundice can occur at any age and in either sex, and is a symptom of many disorders: liver disease, gallstones, pancreatic cancer, and acute biliary obstruction. The normal plasma concentration of bilirubin averages 0.5 mg per 100 ml of plasma. In jaundice, the plasma concentration of bilirubincan rise to as high as Hyperbilirubinemia could be caused by: • Increased bilirubin production • Decreased uptake into the liver cells • Impaired conjugation • Interference with the secretion of conjugated bilirubin Examples of diseases in which hyperbilirubinemia is observed: Hemolytic jaundice: • Results in increased production of bilirubin. • Here more bilirubin is conjugated and excreted than normally, but the conjugation mechanism is overwhelmed, and an abnormally large amount of unconjugated bilirubin is found in the blood. Gilbert's disease: • May be caused by an inability of the hepatocytes to take up bilirubin from the blood. • As a result, unconjugated bilirubin accumulates. Physiological jaundice and Crigler-Najjar syndrome: • Are conditions in which conjugation is impaired. • Unconjugated bilirubin is retained by the body. Dubin-Johnson syndrome: • Is associated with inability of the hepatocytes to secrete conjugated bilirubin after it has been formed. • Conjugated bilirubin returns to the blood. Biliary obstruction: • (For example) biliary calculi causes backup and reabsorption of conjugated bilirubin. • Blood levels of conjugated bilirubin increase.

All of the following statements are true EXCEPT one. Which one is the EXCEPTION? • The replication of DNA involves some RNA intermediates • The replication of DNA involves DNA ligase linking DNA molecules together • The replication of DNA requires unzipping of the DNA molecule • The replication of DNA involves the building of the new ssDNA strand from 3' to 5'

The replication of DNA involves the building of the new ssDNA strand from 3' to 5' *** RNA intermediates are involved to prime the DNA polymerase and later being re-placed by DNA. Replication is the process of completely duplicating the DNA within a cell. The primary enzyme in this process is DNA polymerase, which reads a single strand of DNA from the 3'-end toward the 5'-end while forming the new, complementary, continuous strand from the 5'-end toward its 3'-end. As the DNA polymerase complex moves along the DNA molecule the original complementary strand (lagging strand) is also duplicated. The DNA polymerase that is moving along the lagging strand from the 5'-end toward the 3'-end thus cannot form a continuous copy of the lagging strand. Instead, the DNA polymerase forms approximately 1,000 to 5,000 base long multiple segments (Okazaki fragments), which are joined together by DNA ligase to form a continuous strand. DNA polymerase can only add nucleotides to a pre-existing piece of nucleic acid (primer). During replication, the primer is provided by RNA polymerase, which has no primer requirement. The short 10-base segments created by RNA polymerase are removed, once the DNA has been added to it, by an exonuclease, and the gap in the sequence is filled in by a DNA polymerase. Important point: RNA polymerase synthesizes polypeptide chains from nucleotides and does not require a primer chain. Note: Topoisomerases are responsible for unwinding supercoiled DNA to allow DNA polymerase access to replicate the genetic code. The enzyme DNA gyrase re¬forms the supercoiled structure once the replication fork has passed.

All of the following statements concerning allosteric enzymes are true EXCEPT one. Which one is the EXCEPTION? • They frequently catalyze a committed step early in a metabolic pathway • They often have two or more subunits, each with substrate binding sites that exhibit cooperativity • Allosteric activators cause the enzyme to bind substrate more readily • Allosteric inhibitors cause the enzyme to bind substrate less readily • They follow the Michaelis-Menton kinetics

They follow the Michaelis-Menton kinetics ***This is false; allosteric enzymes usually show a complex relationship between the velocity and substrate concentration. The regulation of metabolic processes is achieved through 2 mechanisms acting directly on enzymes: allosteric regulation and covalent modification. Allosteric regulation: an allosteric enzyme is a regulatory enzyme and has both an active site for the substrate and an allosteric site for an effector (non-active site) of the enzyme. In the absence of the enzyme's effector, the substrate is able to bind to the enzyme's active site and end products are produced. If the effector is present, it will bind to the enzyme's allosteric site. Effectors cause conformational changes that are transmitted through the bulk of the protein to the catalytically active site(s). The hallmark of effectors is that when they bind to enzymes, the effectors alter the catalytic properties of an enzyme's active site. Those that increase catalytic activity are known as positive effectors. Effectors that reduce or inhibit catalytic activity are negative effectors. These modifiers may be either the substrate itself or some other metabolite. For example, ATP inhibits phosphofructokinase (an allosteric enzyme) even though ATP is also a substrate for this enzyme. Covalent modification (the reversible covalent modification of an enzyme): enzyme phosphorylation is the most common form of covalent modification. Phosphorylation occurs on either Ser-OH, Thr-OH, or Tyr-OH groups. Adding or removing a phosphate group (a bulky, heavily negatively-charged functional group) has dramatic effects on protein conformation. Enzyme exists in 2 states, modified (phosphorylated) and unmodified (unphosphorylated), where one is active, and the other is inactive. Enzyme phosphorylation is catalyzed by ATP-dependent protein kinases. Phosphorylated enzymes are dephosphorylated by phosphoprotein phosphatases.

Comparison of Type 1 and Type 2 Diabetes Mellitus Characteristic: Level of insulin secretion Typical age of onset Percentage of diabetes Basic defect Associated with obesity Speed of development of symptoms Development of ketosis Treatment

Type 1 None or almost none Childhood 10-20% Destruction of B cells No Rapid Common if untreated Insulin injections, dietary management Type 2 May be normal or exceed normal Adulthood 80-90% Reduced sensitivity of insulin's target cells Usually Slow Rare Dietary control and weight reduction; occa-sionally oral hypoglycemic drugs

For each letter, choose the most appropriate answer to fill in the blank. P(A) is a major type of protein present in human blood plasma.N It represents an important (B) reserve for the body and, more importantly, plays a crucial role in maintaining the blood's (C) pressure, which tends to draw water (D) the capillaries. • (A) Beta-globulin / albumin / hemoglobin / fibrinogen • (B) Oxygen / iron / amino acid / carbon dioxide • (C) Hydraulic / colloid osmotic / oncotic • (D) Into / out of

(A) Albumin (B) Amino acid (C) Colloid osmotic (D) Into Serum albumin, often referred to simply as albumin, is the most abundant plasma protein in humans and other mammals. Albumin is essential for maintaining the osmotic pressure needed for proper distribution of body fluids between intravascular compartments and body tissues. Albumin also acts as a plasma carrier by non-specifically binding several hydro¬phobic steroid hormones and as a transport protein for hemin and fatty acids. Normal blood value for albumin is 3.5-5.0 g / 100 ml. Albumin is decreased in malnutrition, liver failure, and pregnancy. Colloid osmotic pressure in the plasma is also called oncotic pressure. This pressure tends to draw water into the capillaries by osmosis. Note: The capillary membrane is highly permeable to water as well as to the other substances dissolved in plasma and tissue fluids, except the plasma proteins (mainly albumin). This pressure is important because it prevents plasma loss from the capillaries. This colloid osmotic pressure in the plasma is opposed by the colloid osmotic pressure in the interstitial fluid, which results from the presence of nondiffusible proteins in the interstitial fluid. This pressure tends to draw water out of the capillaries by osmosis. Important: If forces tending to move fluid out of a capillary are greater than forces tending to move fluid in, fluid will leave, and vice versa. 1.The other forces that regulate the movement of fluid across capillary membranes are the fluid or hydraulic pressure inside the capillary (a result of arterial and venous pressures) and the fluid pressure in interstitial fluid. 2. The kidney is the organ that is chiefly responsible for the regulation of the osmot¬ic pressure in the body fluids by regulating the reabsorption of water in response to antidiuretic hormone (ADH or vasopressin). 3. Albumin also transports thyroxin and triiodothyronine as well as fatty acids, bilirubin, bile acids, steroid hormones, pharmaceuticals, and inorganic ions. With the exception of albumin, almost all plasma proteins are glycoproteins.

Dextrans are (A) of (B) produced extracellularly by bacteria and yeast. The enzyme used to produce dextrans is (C), and the substrate is (D). A side product of dextran production is (E), which is formed into (F) and stored intracellularly as reserve nutrients. • (A) Monosaccharides / polysaccharides / oligosaccharides • (B) Glucose / fructose / galactose • (C) Dextran synthase / glucosyl transferase / fructosyl transferase • (D) Maltose / sucrose / lactose • (E) Glucose / fructose / galactose • (F) Starch / glycogen / levans

(A) Polysaccharides (B) Glucose (C) Glucosyl transferase (dextran sucrose) (D) Sucrose (E) Fructose (F) Levans (fructans) Dextrans are polysaccharides of glucose produced extracellulary by bacteria and yeast. The enzyme used to produce dextrans is glucosyl transferase (dextran sucrose), and the substrate is sucrose. A side product of dextran production is fructose which is formed into levans (fructans) and stored intracellularly as reserve nutrients. A few bacteria, notably Streptococcus mutans, produce dextran from sucrose. Dextran is a "sticky" polymer of glucose molecules linked together in a— (1,6) linkages with some a— (1-3) branches. It is produced outside bacterial cells by the enzyme dextran sucrase (glycosyl transferase). This enzyme splits sucrose into glucose and fructose and links the glucose molecules into a dextran polymer. The dextran is deposited as a thick glycocalyx around the cell and seems to be essential for the cariogenicity of Streptococcus mutans. Note: Levans (fructans) also increase the adhesion of bacteria to surfaces of the teeth and promote the formation of dental plaque. It is formed from the fructose moiety of sucrose by the enzyme levan sucrase. Levans are considered to be reserve nutrients for bacteria.

For the following questions, use the same answer choices. 1. Which of the following has the thickest layer of muscle? 2. Which of the following is the major regulator of blood flow? 3. Which of the following contain valves? 4. Which of the following are large vessels that contain deoxygenated blood? is there an EXCEPTION to this rule? 5. Which has higher compliance, veins or arteries? j • Veins • Arteries • Capillaries • Arterioles • Venules

1. Arteries 2. Arterioles 3. Veins 4. Systemic veins -- EXCEPTION -- (pulmonary veins carry oxygenated blood, and pulmonary arteries carry deoxygenated blood) 5. Veins have higher compliance, and arteries have a lower compliance Systemic arteries - transport oxygenated blood under high pressure away from the heart to tissues of the body. Tese arteries have strong muscular walls to withstand the high pressure and low compliance. Note: The pulmonary and umbilical arteries are the only arteries that contain unoxygenated blood. Systemic veins - function as conduits for the transport of unoxygenated blood from the tissues back to the heart. These veins have larger lumens and thinner walls than the arteries the veins accompany but a higher compliance, and act as volume reservoirs. Some contain valves (especially the veins of the limbs) that allow blood to flow toward the heart but not away from it. Note: The pulmonary veins are the only veins that contain oxygenated blood. Capillaries - this is where the exchange of fluid, nutrients, and metabolic waste products occurs between the blood and the interstitial spaces. The capillary walls are very thin. They consist of a single layer of endothelial cells surrounded by a thin basal lamina of the tunica intima. Note: The amount of blood that flows through the capillaries per minute is equal to the amount of blood that flows through the aorta per minute. Arterioles - regulate the flow of blood into capillaries. Blood flow is regulated to meet tissue metabolic needs. Venules - are very small veins that collect blood from the capillaries; venules gradually coa¬lesce into progressively larger veins.

Which structures are the site of highest resistance in the cardiovascular system? • Veins • Arteries • Arterioles • Venules ( When these structures are acted on by nitric oxide or adenosine, they will: ) • Constrict • Dilate • Stay the same This will affect total peripheral resistance in what way? • Increase • Decrease • Stay the same

1. Arterioles 2. Dilate 3. Decrease Arterioles are the last small branches of the arterial system and act as control valves through which blood is released into the capillaries. Arterioles vary in diameter ranging from 30 gm to 400 gm. Any artery smaller than 0.5 mm in diameter is considered to be an arteriole. They have a small lumen and a relatively thick tunica media that is composed almost entirely of smooth muscle, with very little elastic tissue. The intima of an arteriole is composed of endothelial cells lying on a basement membrane with an underlying fine internal elastic lamina in the larger arterioles. Arterioles play a major role in regulating the flow of blood into the capillaries. Blood flow to tissue is mainly regulated by arteriolar diameter. Constriction of the arterioles restricts the flow of blood into the capillaries, while dilation allows the blood to enter the capillaries more freely. Important: Arterioles are the primary resistance vessels and determine the distribution of cardiac output. Arteriolar resistance is regulated by the autonomic nervous system. Remember: Alpha radrenergic receptors are found on the arterioles of the skin and splanchnic circulations. Beta 2-adrenergic receptors are found on arterioles of skeletal muscle. Local blood flow is regulated by tissue metabolism. Various humoral factors can also affect arteriolar diameter, including endothelins (vasoconstrictor), nitric oxide, and adenosine (vasodilators). Sympathetic activation results in an overall vasoconstriction of arterioles and an increase in total peripheral resistance (TPR). Key Point: An increase in arteriolar resistance will increase TPR.

I. The first sign of myocardial infarction in a patient is a high plasma level of which enzyme listed below? 2. In liver disease, which two of these enzymes will be elevated in the plasma? • Creatine kinase (CK) • Lactate dehydrogenase (LDH) • Glutamate-pyruvate transaminase (GPT) • Glutamate-oxaloacetate transaminase (GOT)

1. Creatine Kinase (CK) 2. Glutamate-oxaloacetate transaminase (GOT) Glutamate-pyruvate transaminase (GPT) *** The plasma levels of these enzymes are commonly determined in the diagnosis of myocardial infarction. They are particularly useful when the ECG is difficult to interpret. *** Creatine kinase is the first heart enzyme to appear in the blood after a heart attack, GOT is the next to appear, followed by GPT and LDH. Some enzymes show relatively high activity in only one or a few tissues. The presence of increased levels of these enzymes in plasma thus reflects damage to the corresponding tissue. For example: In the liver: • Glutamate-pyruvate transaminase (GPT): also called alanine aminotransferase (ALT). This enzyme functions in the transamination of alpha-ketoglutarate and L-alanine to glutamate and pyruvate. • Glutamate-oxaloacetate transaminase (GOT): also called aspartate aminotransfer¬ase (AST). *** These two enzymes are elevated in nearly all liver diseases. In the heart: • Creatine kinase (CK): also called creatine phosphokinase (CPK) • Lactate dehydrogenase (LDH): different isozyme characteristic of heart muscle • Glutamate-oxaloacetate transaminase (GOT) • Glutamate-pyruvate transaminase (GPT)

Your patient presents with stage 1 hypertension. His blood pressure is 150 mmHg / 99 mmHg, confirming his diagnosis. 1. Is his pulse pressure normal, high, or low? 2. To bring his blood pressure down to normal, he could attempt to do what to the total peripheral resistance? • Increase it • Decrease it 3. Normally, the mean pressure in the aorta is about 100 mmHg. Eventually, the blood will return via the vena cava at a pressure of 4 mmHg. Where did the blood pressure decrease the most as blood traveled through the body? • Large veins • Large arteries • Arterioles • Venules • Capillaries

1. High 2. Decrease it 3. Arterioles -- the site of highest resistance Although capillaries have a smaller diameter than arterioles, there are vastly more capillaries arranged in parallel than there are arterioles. Thus, most of the pressure drop in the systemic circulation occurs in the arterioles. Pressure decreases as blood moves through the systemic circulation. This pressure gradient is required for blood flow. Remember: blood flow = pressure gradient / resistance The resistance to the flow of blood offered by the entire systemic circulation is called the total peripheral resistance (TPR). The target systolic blood pressure is 120 mmHg, and the recommended diastolic blood pressure is 80 mmHg. However, as blood enters arterioles. the pressure can drop to as low as 30 mmHg. The pulse pressure equals the systolic pressure minus the diastolic pressure (Pulse pressure = SBP-DBP). The most important determinant of pulse pressure is stroke volume. 1. The pressure is highest in the aorta and lowest in the venae cavae. 2. Mean pressure is as follows: in the aorta -- 100 mmHg; at the end of the arterioles -- 30 mmHg; and in the vena cava -- 4 mmHg.

Your patient comes in and says that his physician has diagnosed him with pernicious anemia. As you know, this is caused by the malabsorption of vitamin B12. 1. What protein is crucial in the absorption of vitamin B12? • Gastrin • Intrinsic factor • Pepsin 2. What cell type is the cause of the faulty production of this glycoprotein? • Chief cells • Parietal cells • Mucous neck cells • G cells 3. What type of glands contain these cells? • Pyloric glands • Gastric glands • Cardiac glands • None of the above; they are not part of the glands

1. Intrinsic factor 2. Parietal cells 3. None of the above; they are not part of the glands *** These cells are part of the epithelium and are not part of the gland.s The secretory glands in the stomach can be delineated into 3 regional divisions: • Cardiac glands: mucous secreting found primarily in proximal stomach. • Gastric or oxyntic glands: HC1, pepsinogen, and mucous. • Pyloric glands: mucous secretion into stomach and gastrin into the blood. Found in "Antrum," region near pyloric sphincter. Note: Enteroendocrine cells (G cells) secrete gastrin, which is absorbed in the blood and carried to the gastric glands, where gastrin stimulates the parietal cells to secrete HCL. Cell types in gastric or oxyntic glands: • Mucous neck cells: secrete mucous, and some pepsinogen, migrate to replace surface epithelia. • Parietal cells (oxyntic cells): secrete HC1 and intrinsic factor • Chief cells (peptic cells): pepsinogen Functions of secretions: • Hydrochloric acid - produces an acid environment that helps to kill bacteria and to activate pepsin. This solubilizes connective tissue. Secretion is increased by acetylcholine, gastrin, and histamine. • Pepsin - proteolytic enzyme secreted in an inactive form (pepsinogen) and converted by stomach acidity or by autocatalysis to pepsin. Active at pH <5.0. • Mucous - viscous and alkaline, produces a barrier along the walls of the stomach to protect the stomach from the acid and from abrasion. • Intrinsic factor - a glycoprotein that is essential for normal absorption of vitamin B12 in the intestine. Without intrinsic factor, pernicious anemia will develop.

For the following questions, use the same answer choices. 1. Which circuit supplies the alveoli of the lungs? 2. Which circuit supplies the connective tissue of the lungs? 3. Which has a lower blood pressure? 4. Which has a greater volume of blood flow per minute? 5. Which circuit involves the thick-walled left ventricle? • Pulmonary circuit • Systemic circuit • Both • Neither

1. Pulmonary circuit 2. Systemic circuit 3. Pulmonary circuit 4. Neither (they have the same, about 5 L/min) 5. Systemic circuit The vessels of the circulatory system can be divided into two separate circuits, each of which leaves and returns to the heart. The pump for the pulmonary circuit, which circulates blood through the lungs, is the right ventricle. The left ventricle is the pump for the systemic circuit, which provides the blood supply for the tissue cells of the body. 1. Pulmonary circuit - Pulmonary circulation transports oxygen-poor blood from the right ventricle to the lungs where blood picks up a new blood supply. Then the pulmonary circulation returns the oxygen-rich blood to the left atrium. Note: The vessels of this circuit supply only the alveoli. 2. Systemic circuit - The systemic circulation provides the functional blood supply to all body tissue. The systemic circulation carries oxygen and nutrients to the cells and picks up carbon dioxide and waste products. Systemic circulation carries oxygenated blood from the left ventricle, through the arteries, to the capillaries in the tissues of the body. From the tissue capillaries, the deoxygenated blood returns through a system of veins to the right atrium of the heart. Note: The vessels of this circuit transport blood to all tissues of the body except the alveoli Note: The volume of blood flow per minute (5 L/min) is the same in both circuits. Remember: 1. Mean arterial blood pressure = cardiac output x total peripheral resistance 2. Vascular compliance = rate of change of the vascular volume / change in pressure 3. Blood pressure in the pulmonary circuit is much lower than that of the systemic circulation, because pulmonary arterioles are usually dilated and have little resistance to blood flow. The pulmonary vessels are highly compliant, allowing the pulmonary circuit to store blood volume without changing blood pressure.

Your patient has just finished her 2-hour appointment and is eager to get out o the office. She stands up from the chair very fast, and quickly becomes dizzy and nearly faints. This is termed orthostatic hypotension. 1. Which of the following receptors are most important in the short-term regulation of her blood pressure and returning it to normal? • Stretch receptors in the carotid sinus • Chemoreceptors in the aortic bodies • Chemoreceptors in the carotid bodies • Stretch receptors in the pulmonary circulation 2. This drop in blood pressure will cause what to happen? • Sympathetic impulses to increase • Parasympathetic impulses to increase • Both to increase • Neither to increase 3. The effect on the heart will be: • Increased heart rate, decreased stroke volume • Increased heart rate, increased stroke volume • Decreased heart rate, decreased stroke volume • Decreased heart rate, increased stroke volume

1. Stretch receptors in the carotid sinus 2. Sympathetic impulses to increase 3. Increased heart rate, increased stroke volume The baroreceptor regulatory system is composed of two groups of stretch receptors: (1) one group in the carotid sinuses near the bifurcations of the common carotid arteries in the neck and (2) a second group in the arch of the aorta. These receptors detect changes in blood pressure and feed the information back to the cardiac control center and the vasomotor center in the medulla. In response, these control centers alter the ratio between sympathetic and parasympathetic output. If the pressure is too high, a dominance of parasympathetic impulses will reduce the pressure by slowing the heart rate, reducing stroke volume, and dilating blood "reservoir" vessels. If the pressure is too low, a dominance of sympathetic impulses will increase the pressure by increasing the heart rate and stroke volume and constricting "reservoir" vessels. Stretch receptors in the carotid sinus are stimulated by elevated blood pressure, resulting in the activation of the parasympathetic nervous system and inhibition of the sympathetic nervous system to reduce blood pressure back toward its set point. Chemoreceptors in the carotid and aortic bodies, as well as chemoreceptive neurons in the vasomotor center of the medulla itself, detect increases in carbon dioxide, decreases in blood oxygen, and decreases in pH (which is really an increase in hydrogen ion concentration). This information feeds back to the cardiac control center and vasomotor control center of the medulla, which, in turn, alter the ratio of parasympathetic and sympathetic output. When oxygen drops, carbon dioxide increases, and/or pH drops, a dominance of sympathetic impulses increases heart rate and stroke volume and constricts "reservoir" vessels, in response. Stretch receptors in the atria and pulmonary circulations are stimulated by an expansion of blood volume. They DO NOT directly respond to changes in systemic arterial blood pressure.

Patients occasionally come to your office and claim that they are having---- trouble maintaining their oral health. For each of the following problems, try and match the most appropriate lobe of the cerebrum that is not functioning properly. Patients' complaints are: 1. I always forget if I brushed my teeth already. I just cannot remember if I already did -- so I just assume I did. 2. I ummm ... just cannot make my wrist move the brush ... um ... but ... and ...why do I need ... to brush my teeth? 3. Every time I grasp my brush, it won't fit in my mouth. It also hurts to have the water on my teeth. 4. I brush every day, but I have trouble getting toothpaste on my brush. I have no trouble get¬ting my brush to my mouth, but I just cannot manage to see the toothpaste and the brush. Lobes of the cerebrum are: • Temporal • Frontal • Parietal • Occipital

1. Temporal lobe -- this patient will also have trouble hearing you respond 2. Frontal Lobe -- motor trouble, and trouble with language expression 3. Parietal lobe -- sensations 4. Occipital lobe -- patient has vision troubles -- tell him or her to put toothpaste directly on his or her teeth anduse the brush as normal The cerebrum (cerebral cortex), the largest region of the brain, occupies the superior portion of the cranial cavity. The cerebrum consists of right and left hemispheres. The right controls the left side of the body; the left hemisphere, the right. The corpus callosum is a mass of nerve fibers connecting the hemispheres. Each cerebral hemisphere is divided into four lobes, based on anatomical landmarks and functional differences. The lobes are named for the cranial bones that overlie them. Note: In addition to the functions of the primary areas in each lobe, the vast majority of the cerebral cortex is involved in associative and higher order functioning such as ideation, language, and thought.

Which of the following RNA mutations is least likely to have a significant effect on the product protein? • The elimination of the third amino acid in a codon • The elimination of the first amino acid in a codon • A substitution of the third amino acid in a codon • A substitution of the first amino acid in a codon

A substitution of the third amino acid in a codon *** Due to the "wobble" effect Degeneracy of the genetic code: There are 64 different triplet codons, and only 20 amino acids. Unless some amino acids are specified by more than one codon (sometimes referred to as a triplet), some codons would be completely meaningless. Therefore, some redundancy is built into the system: some amino acids are coded for by multiple codons. In some cases, the redundant codons are related to each other by sequence; for example, leucine is specified by the codons CUU, CUA, CUC, and CUG. Note how the codons are the same except for the third nucleotide position (at the 3 '-end). This third position is known as the "wobble" position of the codon. This is because in a number of cases, the identity of the base at the third position can wobble, and the same amino acid will still be specified. This property allows some protection against mutation --- if a mutation occurs at the third position of a codon, there is a good chance that the amino acid specified in the encoded protein won't change. Important: Only tryptophan, methionine, and selenocysteine are coded by just one codon. The other 18 amino acids are coded by two or more. Codons that specify the same amino acid are called synonyms. Several of the codons serve special functions: 1. Initiation codon (AUG) -- signals the beginning of polypeptide chains and codes for methionine: thus all proteins begin with methionine. 2. Termination codons (UAA, UAG, and UGA) -- signal the end of polypeptide chain synthesis. These codons are also referred to as stop codons or nonsense codons. 1. An anticodon is a specific sequence of three nucleotides in a transfer RNA, complementary to a codon for an amino acid in a messenger RNA. 2. Remember: The two RNAs are paired antiparallel -- the first base of the codon (always reading in the 5' -- 3' direction) pairing with the third base of the anticodon. For example, if the anticodon on a transfer RNA is 5' ACG 3', then its corresponding codon on the messenger RNA would be 5' CGU 3'.

A sequence of DNA is "T-A-G-T-A-T-C-A-T," What would the complementary RNA sequence be? • A-T-C-A-T-A-G-T-A • A-U-C-A-U-A-G-U-A • U-T-C-U-T-U-G-T-U

A-U-C-A-U-A-G-U-A A complete DNA molecule consists of two polynucleotide chains that run in opposite directions to one another. The two strands of DNA form a double helix that runs antiparallel such that one strand runs 5' to 3' ("five prime to three prime') while the other one runs 3' to 5'. The purine and pyrimidine bases that are opposite one another (adenine with thymine and guanine with cytosine) in each polynucleotide chain are linked together by hydrogen bonds. The A-T base pair has two hydrogen bonds while the G-C base pair has three. This base pairing (A with T and G with C) is known as complementary base pairing. Remember: This complementary base pairing can also occur in RNA and between RNA and DNA; however, uracil substitutes for thymine in RNA. Uracil base pairs with adenine. Important point: The A-T base pair promotes helix stabilization in DNA but does not do so in RNA. 1. In all DNA, the number of thymine residues equals the number of adenine Notes residues. Also, the number of guanine residues equals the number of cytosine residues. 2. Purines are the larger of the two types of bases found in DNA. 3. In addition, the sum of purine residues equals the sum of pyrimidine residues (A + G = T + C). 4. The melting temperature of the double helix is a function of the base composition with a higher GC content having a higher melting temperature and an increased stability of the double helix.

C an action potential reaches a skeletal muscle cell, which of the following is----\ the proper order of substances moving into and through the muscle cell? iy • Acetylcholine, Calcium, Troponin, Tropomyosin, Myosin heads • Calcium, Acetylcholine, Troponin, Tropomyosin, Myosin heads • Acetylcholine, Calcium, Tropomyosin, Troponin, Myosin heads • Calcium, Acetylcholine, Tropomyosin, Troponin, Myosin heads

Acetylcholine, Calcium, Troponin, Tropomyosin, Myosin heads When an action potential arrives at a muscle cell, the action potential causes Ca" to be released from the sarcoplasmic reticulum. As intracellular Ca" is increased, Ca' begins to bind to troponin C on the thin filaments, causing a conformational change in troponin that permits the interaction between actin and myosin. After calcium binds with troponin, tropomyosin moves from its blocking position, permitting actin and myosin to interact. High-energy myosin binds weakly to actin subunits; however, when inorganic phosphate is released from myosin, the myosin bind tightly to the actin subunits. Energy stored in the high-energy myosin is discharged, and the myosin heads swivel, pulling on the thin filaments. This repeated pulling of the thin filaments past the thick filaments toward the centers of the sarcomeres draws the Z lines closer together, and the muscle fiber shortens (contracts). This process is called the Sliding Filament Theory. Note: This process is repeated as long as calcium ions are bound to troponin and ATP is available. Once calcium ions are returned to the sarcoplasmic reticulum, tropomyosin moves back into its blocking position and prevents further interaction between high-energy myosin and actin subunits. Contraction ceases, and the muscle fibers relax. Important: In the contractile cycle, the dissociation of the actomyosin complex results from ATP replacing ADP on the myosin heads. Remember: Composition of myofilaments • Thick filament - composed mainly of the protein myosin. • Thin filaments - composed mainly of the protein actin.

All of the following statements concerning transamination reactions are true EXCEPT one. Which one is the EXCEPTION? • These reactions involve the transfer of an amino group from one amino acid to an a-keto acid • The enzymes that catalyze these reactions are known as transaminases or aminotransferases • Glutamate and a-ketoglutarate are often involved in these reactions, serving as one of the amino acid/a-keto acid pairs • Pyridoxal phosphate (PLP), which is derived from vitamin B6 serves as the cofactor for these reactions • All amino acids participate in these reactions at some point in their catabolism

All amino acids participate in these reactions at some point in their catabolism *** This is false; lysine, serine, and threonine are not transaminated. The first step in the catabolism of most amino acids involves the removal of the a - amino group. Once removed, this nitrogen can be incorporated into other compounds or excreted. Nitrogen is transferred from one amino acid to another by transamination reactions, which always involve two different pairs of amino acids and their corresponding a-keto acids. Note: Glutamate and a-ketoglutarate usually serve as one of the pairs; transaminases (aminotransferases) catalyzed the transfer of amino groups; all transaminases require the coenzyme pyridoxal phosphate. In contrast to transamination reactions that transfer amino groups, oxidative deamination reactions result in the liberation of the amino group as free ammonia (NH3). These reactions occur primarily in the liver and kidney and provide a¬ketoacids (for energy) and ammonia (which is a source of nitrogen in urea synthesis). Note: Enzymes involved in deamination reactions include glutamate dehydrogenase (for glutamate), histidase (for histidine), and serine dehydratase (for serine and threonine). All aminotransferases (transaminases) share a common prosthetic group, pyridoxal phosphate (PLP). PLP is the coenzyme form of pyridoxine or vitamin B6. It functions as an intermediate carrier of amino groups at the active site of aminotransferases. PLP undergoes reversible transformations between its aldehyde form, pyridoxal phosphate (PLP), which can accept an amino group, and its aminated form, pyridoxamine phosphate (PMP), which can donate its amino acid to an a-keto acid.

Your patient tells you that he just had a heart bypass operation. He says that' they used a vein from his leg and re-routed blood that previously flowed through his left anterior descending coronary artery (often referred to as the widow maker). Which of the following explanations is correct in answering how a vein can adequately replace an artery? • Although veins have higher compliance normally, when under high pressure, compliance decreases, and so the vein acts very similar to an artery when put in these conditions. • Although veins have lower compliance normally, when under the high pressure, compli-ance increases, and so the vein acts very similar to an artery when put in these conditions. • Although veins have higher resistance normally, when under the high pressure, resistance decreases, and so the vein acts very similar to an artery when put in these conditions. • Although veins have lower resistance normally, when under high pressure, resistance increases, and so the vein acts very similar to an artery when put in these conditions.

Although veins have higher compliance normally, when under high pressure, com-pliance decreases, and so the vein acts very similar to an artery when put in these conditions. Total peripheral resistance (TPR) regulates the flow of blood from the systemic arterial circulation into the venous circulation. Cardiac output regulates the flow of blood from the veins back into the arterial side. The amount of blood located in the systemic veins is regulated by their compliance. Sympathetic activation decreases venous compliance and returns more blood back to the heart, increasing cardiac output and blood pressure, thus causing more blood to be pushed through the arterial circulation. The ability of a blood vessel wall to expand and contract passively with changes in pressure constitutes an important function of large arteries and veins. This ability of a vessel to distend with increasing transmural pressure (inside minus outside pressure) is quantified as vessel compliance (C), which is the change in volume (DV) divided by the change in pressure (DP). Important points about compliance: (1) Compliance decreases at higher pressures and volumes (i.e., vessels become "stiffer" at higher pressures and volumes). (2) At lower pressures, the compliance of a vein is about 10 to 20 times greater than that of an artery. Therefore, veins can accommodate large changes in blood volume with only a small change in pressure. However, at higher pressures and volumes, venous compliance becomes similar to arterial compliance. This makes veins suitable for use as arterial by-pass grafts. Relative volumes of blood at rest in different parts of the adult cardiovascular system: • 66% - in the systemic veins, venules • 6% - in the heart • 11% - in the systemic arteries, arterioles • 5% - in the capillaries • 12% - in the pulmonary loop

Starch molecules are broken down by enzymes known as: j • Oxygenases • Isomerases • Peroxidases • Amylases

Amylases Amylase is the name given to glycoside hydralase enzymes that break down starch into glu-cose molecules. Amylase is also known as ptyalin. Although the amylases are designated by different Greek letters, they all act on a-1,4-glycosidic bonds. Classification of amylases: • a-amylases: By acting at random locations along the starch chain, a-amylase breaks down long-chain carbohydrates, ultimately yielding maltotriose and maltose from amylose, or maltose, glucose, and "limit dextrin" from amylopectin. Because a-amylase can act anywhere on the substrate, a-amylase tends to be faster acting than (3-amylase. In animals,a-amylase is a major digestive enzyme. Note: In human physiology, both the salivary and pancreatic amylases are a-amylases. • (3-amylase: working from the non-reducing end, (3-amylase catalyzes the hydrolysis of the second a-1,4 glycosidic bond, cleaving off two glucose units (maltose) at a time. • y-amylase: in addition to cleaving the last a-1,4-glycosidic linkages at the non-reducing end of amylose and amylopectin, yielding glucose, y-amylase will cleave a-1,6¬glycosidic linkages. 1. "Limit dextrins" are various branched polysaccharide fragments that remain fol¬Notes lowing the hydrolysis of starch. 2. Disaccharides and small glucose polymers are hydrolyzed at the intestinal brush border by lactase, sucrase, maltase, and alpha-dextrinase. 3. Remember: Only monosaccharides (e.g., glucose, galactose, fructose) are ab¬sorbed in the small intestine. Lactase degrades lactose to glucose and galactose, isomaltase cleaves a glucose linked 1,6 to another glucose as is found at the branch points in starch and glycogen, and sucrase degrades sucrose to glucose and fructose.

Which structure functions to control complex patterns of voluntary motor behavior? • Hypothalamus • Hippocampus • Basal ganglia • Thalamus

Basal ganglia Collections of nerve cells (nuclei) lie at the base of the cerebrum (subcortical) in structures called the: • Basal ganglia - includes the caudate nucleus, putamen, globus pallidus, substantia nigra, and the subthalamic nucleus. The basal ganglia's function is to control complex patterns of voluntary motor behavior. • Thalamus - a large ovoid mass of gray matter that relays all sensory stimuli (except olfactory) as they ascend to the cerebral cortex. Output from the cortex also can synapse in the thalamus. • Hypothalamus - controls many homeostatic processes, which are often associated with the autonomic nervous system. The hypothalamus is involved in regulating body temperature, water balance, appetite, gastrointestinal activity, sexual activity, sleep, and even emotions such as fear and rage. The hypothalamus also regulates the release of the hormones of the pituitary gland; and thus the hypothalamus greatly affects the endocrine system. Important: Stimulation of the posterior hypothalamus by a reduction in core temperature will produce shivering. • Hippocampus - functions in the consolidation of memories and in learning. The basal ganglia are a group of anatomically closely related subcortical nuclei. Damage to these nuclei does not cause weakness, but can cause dramatic motor abnormalities. Clinical syndromes associated with damage to these nuclei include Parkinsonism, Hemiballismus (hemichorea), and Huntington's chorea.

Some proteins are produced by ribosomes that are attached to the cytosolic surface of the rough endoplasmic reticulum. Which of the following is not a possible destiny of these proteins? • Becoming a collagenase • Becoming a sodium/potassium pump • Becoming a proteolytic enzyme • Becoming a ribosome

Becoming a ribosome *** Because ribosomes are found in the cytoplasm of cells and are made of rRNA. Ribosomes are the protein-synthesizing machines of the cell. They translate the information encoded in messenger RNA (mRNA) into a polypeptide. Ribosomes are small structures found floating free in the cytoplasm (polyribosomes) that contain rRNA and protein. At a ribosome, amino acids are linked together in the order specified by mRNA to form a polypeptide or protein (this process is called protein synthesis or translation). Ribosomes have enzymatic activity. They catalyze the formation of peptide bonds, which link amino acids to one another. Many ribosomes in different stages of translation can be attached to a single mRNA strand, thus multiplying its effect. Some are attached to the cytosolic surface of the endoplasmic reticulum membrane (when they are attached, it is called rough endoplasmic reticulum, RER): others remain as free ribosomes in the cytoplasm. Proteins formed by ribosomes attached to the RER are destined for secretion from the cell, incorporation into the plasma membrane, or formation of lysosomes. Since all protein synthesis begins on free ribosomes, attachment of a ribosome to the ER requires the presence of a specific sequence at the amino end of the growing protein chain to signal the attachment of the ribosome to the ER. 1. The 70s ribosomes are the sites of protein synthesis (translation) in Notes bacterial cells and chloroplasts. 2. The 80s ribosomes are the sites of protein synthesis (translation) in the cytoplasm of eukaryotic cells. 3. The other answer choices are incorrect because: - A collagenase involves secretion from the cell. - A pump protein involves incorporation into the plasma membrane. - A proteolytic enzyme involves incorporation into lysosomes.

Place the following phases of gastric secretion in their proper order: • Intestinal phase • Gastric phase • Cephalic phase

Cephalic phase Gastric phase Intestinal phase Phases of Gastric Secretion: • Cephalic phase ("wake up call'): sensations of thoughts about food are relayed to the brainstem, where parasympathetic signals to the gastric mucosa are initiated. This directly stimulates gastric juice secretion and stimulates the release of gastrin, which prolongs and enhances the effect. • Gastric phase (`full steam ahead'): the presence of food, specifically the distension food causes, triggers local and parasympathetic nervous reflexes that increase the se-cretion of gastric juice and gastrin (which further amplifies gastric juice secretion). Products of protein digestion can also trigger the gastrin mechanism. • Intestinal phase ("step on the brakes'): as food moves into the duodenum, the pres-ence of fats, carbohydrates, and acid stimulates hormonal and nervous reflexes that in-hibit stomach activity.

All of the following are main structures of the hindbrain EXCEPT one. Which one is the EXCEPTION? • Medulla oblongata • Pons • Cerebral hemispheres • Cerebellum

Cerebral hemispheres The human forebrain (prosencephalon) is made up of: • A pair of cerebral hemispheres, called the telencephalon • A group of structures located deep within the cerebrum that make up the dien¬cephalon Main Structures of the Hindbrain (rhombencephalon): • Cerebellum - lies beneath the cerebrum just above the brain stem. The cerebellum's functions are concerned with coordinating voluntary muscular activity, maintaining equilibrium, and coordination. • Pons - connects the cerebellum with the cerebrum and links the midbrain to the medulla oblongata; serves as the exit point for cranial nerves V, VI, and VII. • Medulla oblongata - the medulla looks like a swollen tip to the spinal cord. Nerve impulses arising here rhythmically stimulate the intercostal muscles and diaphragm -- making breathing possible. Also regulates the heartbeat and regul¬ates the diameter of arterioles, thus adjusting blood flow. Note: The neurons controlling breathing have mu (p) receptors, the receptors to which opiates, like heroin, bind. This accounts for the suppressive effect of opiates on breathing. The brain stem lies immediately inferior to the cerebrum, just anterior to the cerebellum. The brain stem consists of the midbrain, pons, and medulla oblongata. The midbrain (mesencephalon) connects dorsally with the cerebellum and contains large voluntary motor nerve tracts. The limbic system is a primitive brain area deep within the temporal lobe. Besides initiating basic drives -- hunger, aggression, and emotional feelings and sexual arousal -- the limbic system screens all sensory messages traveling to the cerebral cortex.

The most abundant glycosaminoglycan in the body is: ) • Keratan sulfate • Dermatan sulfate • Chondroitin sulfate • Heparin sulfate

Chondroitin sulfate Chondroitin sulfate is a major constituent in various connective tissues, especially in the ground substance of blood vessels, bone, and cartilage. In cartilage chondroitin sulfate, provides structure by holding water and nutrients, and allowing other molecules to move through cartilage - an important property, as there is no blood supply to cartilage. Chondroitin may work by acting as a building block for proteoglycan molecules, and may also have anti-inflammatory properties. Important: In our joints, chondroitin sulfate contributes to strength, flexibility, and shock absorption. Remember: The extracellular space in animal tissues is filled with a gel-like material, the extracellular matrix, also called ground substance, which holds the cells of a tissue together and provides a porous pathway for the diffusion of nutrients and oxygen to individual cells. The ground substance is composed of an interlocking meshwork of heteropolysaccharides (glycosaminoglycans), most covalently linked to protein forming proteoglycans, and fibrous proteins. Important: Hyaluronidase will promote depolymerization of the extracellular matrix (ground substance). Hyaluronidase is an enzyme that splits hyaluronic acid (glycosaminoglycan) and so lowers its viscosity and increases the permeability of connective tissue and the absorption of fluids. 1. Heparin contains the largest proportion of sulfate (yes, even more than he- Notes parin sulfate). 2. Hyaluronic acid contains the least proportion of sulfate.

Which statement concerning rods and cones is incorrect? • Rods contain rhodopsin - a photopigment • Cones are responsible for color vision • Rods are used for dark adaptation • Rods and cones are located in the retina • Cones are more abundant than rods

Cones are more abundant than rods The retina is the innermost layer (nervous tissue) of the eye. The retina receives visual stimuli and sends the information to the brain. Photoreceptor cells called rods and cones compose the visual receptors (for the optic nerve) of the retina. Rods and cones contain photopigments. There are four different photopigments, each consisting of a protein called an opsin to which a chromophore molecule called retinal is attached. Opsins differ from pigment to pigment and confer specific light-sensitive properties on each photopigment. Note: Retinal is produced from vitamin A. Rods contain a photopigment called rhodopsin. Their response indicates different degrees of brightness, but the entire rod system is characterized by a relative lack of color discrimination. Rods are numerous in the periphery of the retina. Cones are primarily responsible for color vision. There are three different types of cones (red, green, and blue). Each one contains a different photopigment and is selectively sensitive to a particular wavelength of light. They are concentrated in the center of the retina, especially in the fovea. 1. During dark adaptation (night vision), rhodopsin is synthesized in the Notes rods. 2. Cones are the principal photoreceptors during daylight or in brightly lit areas. 3. Rods are more abundant, have higher sensitivity, and lower acuity compared to cones.

In a single muscle, there are both intrafusal and extrafusal fibers. All of the following statements are true in the description of intrafusal fibers EXCEPT one. Which one is the EXCEPTION? \---__ ....----/) • Contain nuclear bag fibers that detect fast, dynamic changes • Innervated by gamma-motor neurons • Contain nuclear linking fibers that transmit afferent signals • Encapsulated in sheaths to form muscle spindles • Contain nuclear chain fibers that detect static changes

Contain nuclear linking fibers that transmit afferent signals Two Types of Muscle Fibers: 1. Extrafusal Fibers • Fibers that make up the bulk of the muscle • Innervated by alpha-motor neurons (efferent neurons) • Provide the force for muscle contraction 2. Intrafusal Fibers • Are encapsulated in sheaths to form muscle spindles • Innervated by gamma-motor neurons (efferent neurons) Two Types of Intrafusal Fibers: 1. Nuclear bag fibers • Detect fast, dynamic changes in muscle length and tension. • Innervated by group la afferents - fastest in the body. 2. Nuclear chain fibers • Detect static changes in muscle length and tension. • Innervated by the slower group II afferents. Remember: 1. A sensory (afferent) neuron transmits afferent nerve impulses from the receptor (peripheral ending of a sensory neuron) to the spinal cord. 2. A motor (efferent) neuron transmits efferent nerve impulses from the integrating center (in the spinal cord) to an effector (muscle cell).

Which of the following structures of the eye does not change in shape? • Lens • Retina • Cornea • Iris

Cornea Basic anatomy of the eye: • Cornea - The crystal clear dome that covers the front of the eye. The majority (70%) of the bending (refracting) of light rays is accomplished by the cornea. The shape of the cornea does not change (with the exception of small changes that occur over a lifetime). • Lens - The crystalline lens finishes the focusing of light. The lens helps to "fine-tune" vision, and it is able to change shape to allow focus on near objects. When the lens becomes cloudy, it is called a cataract. • Pupil - This is the opening in the middle of the iris. • Iris - This is the part of the eye that gives it color (i.e., blue, green, brown). The iris functions like a shutter in the camera analogy, allowing more or less light into the eye. • Retina - This is a thin layer of nerve tissue that senses light. Specialized cells called rods and cones convert light energy into nerve signals that travel through the optic nerve to the brain. The retina is analogous to the film in a camera. • Fovea - This is the center of the retina that receives the focus of the object of regard. Nerve cells are more densely packed in this area, so images that are focused on the fovea can be seen in greater detail. • Optic nerve - This is the nerve that runs from the eyeball to the brain. The optic nerve carries information from the retina to the brain for interpretation. Note: The eyeball itself is divided into two segments, each filled with fluid. The anterior segment has two chambers (anterior and posterior), which are both filled with aqueous humor (watery fluid), and the posterior segment is filled with vitreous humor (thick, gelatinous material).

ldison's disease occurs when the adrenal glands do not produce enough of tormone and, in some cases, the hormone • Glucagon, estrogen • ADH, oxytocin • Cortisol, aldosterone • Epinephrine, norepinephrine

Cortisol, aldosterone Addison's disease (also called adrenal insufficiency, or hypocortisolism) is a life-threatening condition caused by partial or complete failure of adrenocortical function (insufficient glucocorticoids and mineralocorticoids). More than 90% of the cortex of the adrenal must be destroyed before obvious symptoms occur. In 70% of people with Addison's disease, the cause is not precisely known, but the adrenal gland are affected by an autoimmune reaction in which the body's immune system attacks and destroys the adrenal cortex. In the other 30%, the adrenal glands are destroyed by cancer, an infection such as tuberculosis, or another identifiable disease. The disease is characterized by weight loss, muscle weakness, fatigue, low blood pressure, and sometimes darkening of the skin in both exposed and nonexposed parts of the body. Oral signs consist of diffuse pigmentation of the gingiva, tongue, hard palate, and buccal mu¬cosa. Cortisol is normally produced by the adrenal glands, located just above the kidneys. It belongs to a class of hormones called glucocorticoids, which affect almost every organ and tissue in the body. Cortisol's most important job is to help the body respond to stress. Among cortisol's other vital tasks, cortisol: • Helps maintain blood pressure and cardiovascular function • Helps slow the immune system's inflammatory response • Helps balance the effects of insulin in breaking down sugar for energy • Helps regulate the metabolism of proteins, carbohydrates, and fats • Helps maintain proper arousal and sense of well-being Aldosterone belongs to a class of hormones called mineralocorticoids, also produced by the adrenal glands. It helps maintain blood pressure and water and salt balance in the body by helping the kidney retain sodium and excrete potassium. When aldosterone production falls too low, the kidneys are not able to regulate salt and water balance, causing blood volume and blood pressure to drop.

During exercise, which of the following is thought to be an immediate source for high-energy phosphate groups with which to replenish ATP? • NADH • FADH2 • Phosphoenolpyruvate • Creatine phosphate

Creatine phosphate Creatine phosphate is one of the basic muscle energy stores, particularly in fast-switch glycolytic fibers. Normal metabolism cannot supply energy as quickly as a muscle cell can use it, so an extra storage source is needed. The phosphate group can be quickly transferred to ADP to regenerate the ATP necessary for muscle contraction. The phosphate compounds found in living organisms can be divided arbitrarily into two groups based on their standard free energies of hydrolysis. 1. Higher phosphate group-transfer potential than ATP: • Phosphoenolpyruvate • Carbamoyl phosphate • Acetyl phosphate • Creatine phosphate • 1,3 -diphosphoglyceric acid 2. Lower phosphate group-transfer potential than ATP: • Glucose- 1 -phosphate • Glucose-6-phosphate • Fructose-1,6-diphosphate • Creatine

Which of the following components of the electron transport chain accepts only electrons? • FMN (flavin mononucleotide) • Coenzyme Q (ubiquinone) • Cytochrome b • Oxygen

Cytochrome b -- the cytochromes accept only electrons. The other components accept hydrogen and electrons. The majority of the energy conserved during catabolism reactions occurs near the end of the metabolic series of reactions in the electron transport chain. The electron transport, or respiratory chain, gets its name from the fact electrons are transported to meet up with oxygen from respiration at the end of the chain. This chain is present in the inner mitochondrial membrane and is the final common pathway by which electrons derived from different fuels of the body flow to oxygen. Electron transport and ATP synthesis by oxidative phosphorylation proceed continuously in all cells of the body that contain mitochondria. Components of the electron transport chain: • FMN: receives electrons from NADH and transfers them through Fe-S centers to coenzyme Q. FMN is derived from riboflavin. Remember: NAD is derived from niacin. • Coenzyme Q: receives electrons from FMN and also through Fe-S centers from FADH2. Coenzyme Q is not derived from a vitamin (the body synthesizes it). • Cytochromes (b, c, a, and a3): receive electrons from the reduced form of coenzyme Q. Each cytochrome consists of a heme group associated with a protein; cytochrome a + a3 is also called cytochrome oxidase. Heme is synthesized from glycine and succinyl CoA in humans. Heme is not derived from a vitamin. • Oxygen: ultimately receives the electrons at the end of the chain and is reduced to water. Remember: A coenzyme is a nonprotein substance (organic cofactor) that combines with an apoenzyme (the protein portion of a complex enzyme) to form a haloenzyme (a complete, catalytically active enzyme system).

Which of the following pairings is incorrect regarding the absorption in the small intestine? • Fructose - Facilitated diffusion • Free fatty acids - Simple diffusion • Dipeptides - Primary active transport • Glucose - Secondary active transport

Dipeptides - Primary active transport *** Dipeptides are absorbed by secondary active transport. The bulk of dietary lipid is neutral fat or triglyceride, composed of a glycerol backbone with each carbon linked to a fatty acid. Additionally, most foodstuffs contain phospholipids, sterols like cholesterol, and many minor lipids, including fat-soluble vitamins. In order for the triglyceride to be absorbed, two processes must occur: • Large aggregates of dietary triglyceride, which are virtually insoluble in an aqueous environment, must be broken down physically and held in suspension -¬a process called emulsification. • Triglyceride molecules must be enzymatically digested to yield monoglycerides and free fatty acids, both of which can efficiently diffuse into the enterocyte. *** The key players in these two transformations are bile salts and pancreatic lipase, both of which are mixed with chyme and act in the lumen of the small intestine. Dipeptides and amino acids are the end products of protein digestion. The final digestive stage occurs by brush border peptidases, and absorption immediately follows. Absorption across the brush order occurs by multiple secondary active transporters utilizing either the sodium or hydrogen gradients. Disaccharides and small glucose polymers are hydrolyzed at the brush border by lactase, sucrase, maltase, and alpha-dextrinase. The resultant monosaccharides, glucose and galactose, are then absorbed by secondary active transporters driven by the sodium gradient. Fructose absorption is mediated by facilitated diffusion.

Trypsinogen is transformed into trypsin as a result of the cleavage of a single peptide bond by: • Endopeptidase • Alanine aminotransferase • Enteropeptidase • Pancreatic lipase

Endopeptidase The presence of amino acids (from protein digestion) in the small intestine (specifically the duodenum) stimulates the release of cholecystokinin (CCK). This hormone cause the release of the pancreatic zymogens (e.g., trypsinogen, chymotrypsinogen, proelastase, and procarboxypeptidase A and B) and the contraction of the gallbladder to deliver bile to the duodenum. The pancreatic proteases (e.g., trypsin, chymotrypsin, elastase, and carboxypep¬tidase A and B) are secreted in inactive forms (zymogens) that are activated in the small intestine as follows: • Trypsinogen is activated to trypsin by enteropeptidase • Trypsin converts trypsinogen, chymotrypsinogen, proelastase, and procarboxy-peptidase A and B to their active forms. Important point: Trypsin can act as an activator for all zymogens of pancreatic proteases 1. Pepsinogen (secreted by chief cells of the stomach) is activated to pepsin by the low pH in the stomach or other activated pepsin molecules. 2. Trypsin cleaves peptide bonds in which the carboxyl group is contributed by lysine and arginine (basic amino acids). 3. Chymotrypsin cleaves peptide bonds in which the carboxyl group is contributed by the aromatic amino acids or by leucine. 4. Elastase cleaves at the carboxyl end of amino acid residues with small, unchanged side chains such as alanine, glycine, or serine. 5. Carboxypeptidase A has little activity on aspartate, glutamate, arginine, lysine, or proline; carboxypeptidase B cleaves basic amino acids, lysine, and arginine. 6. Endopeptidase (for example, trypsin) refers to any of a large group of enzymes that catalyze the hydrolysis of peptide bonds in the interior of a polypeptide chain or protein molecule.

Which of the following best describes an "uncompetitive inhibitor"? • Essentially a noncompetitive inhibitor that can bind only when the substrate is attached • Essentially a competitive inhibitor that can bind only when the substrate is attached • A noncompetitive inhibitor that can be overcome by increasing substrate concentration • An irreversible inhibitor (the two are synonyms)

Essentially a noncompetitive inhibitor that can bind only when the substrate is attached Enzymes are subject to the following types of inhibition: Reversible: 1. Competitive inhibition: the competitive inhibitor resembles the substrate and binds to the active site of the enzyme. The substrate is then prevented from binding to the same active site. The hallmark of competitive inhibition is the inhibition can be overcome by increasing the substrate concentration. 2. Noncompetitive inhibition: the inhibitor and substrate can bind simultaneously to an enzyme molecule. This means that their binding sites do not overlap. Because the inhibitor and substrate do not compete for the same site, noncompetitive inhib¬ition cannot be overcome by increasing the substrate concentration. A noncompet¬itive inhibitor is by definition an allosteric inhibitor. 3. Uncompetitive inhibition: like noncompetitive, the inhibitor and substrate bind at different sites which do not overlap. However, an uncompetitive inhibitor will bind only to an enzyme that has a substrate already attached (ES complex). Remember: The noncompetitive inhibitor binds to either a free enzyme or the ES complex. Irreversible inhibitors are those that combine with or destroy a functional group on the enzyme that is essential for its activity. A classic example is the irreversible inhibition of cyclooxygenase (COX) by aspirin (acetylsalicylate), which acetylates the active site serine residue.

All of the following statements concerning muscle fibers are true EXCEPT one. Which one is the EXCEPTION? • Fast-twitch fibers are about twice as large in diameter • Slow-twitch fibers have a greater resistance to fatigue • The enzymes of oxidative phosphorylation are considerably more active in slow-twitch fibers • Fast-twitch fibers contain more mitochondria and myoglobin • Fast-twitch fibers can deliver extreme amounts of power for a few seconds to a minute

Fast-twitch fibers contain more mitochondria and myoglobin *** This is false; see chart below. (364) 1. "Fast" muscles are for rapid, powerful actions (jumping, short distance running) while "slow" muscles are for prolonged activity (body posture, marathon). 2. Oxidative capacity is related to (1) the number of capillaries, (2) the myoglobin content, (3) the number of mitochondria.

CA you complete the seating of a crown, you ask your patient to tap lightly on the articulator paper. Which of the following statements is correct in describing the physiology of the patient's light tapping? .---._ • The "all or nothing" phenomenon occurs; all fibers in the masseter and medial ptery¬goid are partially stimulated, causing a light contraction • Fractionation occurs; each muscle fiber involved is stimulated only by a fraction of the alpha-motor neurons innervating the fiber, and so the fibers contract lightly • Fractionation occurs; only a few small alpha-motor units are recruited, and the masseter and medial pterygoid muscles contract lightly • The "all or nothing" phenomenon occurs; the muscles that close the mouth are stimu¬lated fully but are countered by stimulation of the muscles that open the mouth, caus¬ing a s light closing of the mouth

Fractionation occurs; only a few small alpha-motor units are recruited and the masseter and medial pterygoid muscles contract lightly The motor unit is the alpha-motor neuron and all of the muscle fibers that it innervates: • Each muscle is composed of several muscle fibers • Each muscle fiber is innervated by a single alpha-motor neuron • Each alpha-motor neuron innervates many muscle fibers • All of the fibers innervated by a motor neuron contract when that motor neuron fires an action potential Remember: The Size Principle -- motor units are recruited in order of the size of the motor unit. If only a small amount of tension is required to perform the movement, then only small motor units will be activated. If greater force is required, more and larger motor units will be recruited. Important: When a patient bites down rapidly on an unexpected hard surface while chewing, the cessation of motor unit recruitment in the jaw closing muscles is caused by periodontal mechanoreceptors. Fractionation means that it is not necessary to activate all of the motor units in a muscle. The contraction of skeletal muscle is controlled by the nervous system. Action potentials traveling down somatic alpha motor neurons cause depolarization of the skeletal muscle fibers at which they terminate. The junction between the terminal of a motor neuron and a muscle fiber is called a neuromuscular junction. When an action potential arrives at a neuromuscular junction, calcium ions enter the nerve terminal, causing the release of acetylcholine from synaptic vesicles within the motor neuron. Acetylcholine then binds to the nicotinic cholinergic receptors in the muscle fiber plasma membrane. This causes depolarization, which triggers an action potential (the action potential travels along the membrane and the t-tubules). This action potential triggers the release of calcium ions from the sarcoplasmic reticulum. This leads to crossbridge formation between actin and myosin. These interactions are responsible for the development of tension and the shortening of the fibers.

Your patient's medical history says that she has von Gierke's disease, She is "N missing the enzyme (?), which converts (?) • Glucose-6-phosphatase, glucose-6-phosphate to glucose • Glucose-6-phosphatase, glucose-6-phosphate to fructose-6-phosphate • Pyruvate carboxylase, pyruvate to phosphoenolpyruvate • Pyruvate carboxylase, pyruvate to 2-phosphoglycerate

Glucose-6-phosphatase, glucose-6-phosphate to glucose Glucose-6-phosphatase (G6P) is the liver enzyme that converts glucose-6-phosphate into glucose. G6P is vital for the release of glucose into the bloodstream from glycogen breakdown (glycogenolysis). Important: Glucose-6-phosphatase, like pyruvate carboxylase, occurs in the liver and kidneys but not in muscle. Therefore, any glucose released from glycogen stores of muscle will be oxidized in the glycolytic pathway. In the liver, the action of glucose-6- phosphatase allows glycogenolysis to generate free glucose for maintaining blood glucose levels. Gluconeogenesis is a biochemical process in which glucose is made from molecules that are not carbohydrates (primarily from amino acids but not fatty acids). This process occurs primarily in the liver, and the process provides glucose for export to other tissues when other sources of glucose are exhausted. Typically, gluconeogenesis involves the conversion of lactic acid or amino acids into pyruvate or phosphoenolpyruvate, which is then converted to glucose. Some key reactions of gluconeogenesis: • Pyruvate oxaloacetate (catalyzed by pyruvate carboxylase) • Oxaloacetate phosphoenolpyruvate (catalyzed by phosphoenolpyruvate carboxy¬kinase) • Fructose-1,6-bisphosphate fructose-6-phosphate (catalyzed by fructose-1,6-bispho-sphatase) • Glucose-6-phosphate -- glucose (catalyzed by glucose-6-phosphatase) 1. Glucose-6-phosphatase does not contain a high-energy bond. 2. In glycolysis, glucose is converted to pyruvate glycolysis is the first part of the respiratory pathway; in gluconeogenesis, pyruvate is converted to glucose.

Which of the following polysaccharides requires the enzyme glucan transferase to breakdown? • Starch • Glycogen • Cellulose • Glycosaminoglycans

Glycogen Polysaccharides are carbohydrates that are polymers of monosaccharides. Polysaccharides are made up of many sugar units joined by condensation reactions (which results in glycosidic bonds). Since polysaccharides have large molecules, they are insoluble. Their main functions in living organisms are to act as storage molecules (starch and glycogen) or as structural materials (cellulose). Homopolysaccharides (starch, glycogen, dextrans, and glucans) contain only a single monosaccharide species. Heteropolysaccharides (glycosaminoglycans) contain a number of different monosacch¬aride species. The two most important storage polysaccharides are starch and glycogen. • Starch is a large, insoluble carbohydrate that forms an important energy store in plants. Starch is a polymer and consists of a large number of a-glucose molecules joined together by condensation reactions. It consists of two main components that may be present in different proportions. Amylose (which is unbranched) forms long straight chains while amylopectin has highly branched chains with alpha-1,4 linkages. Note: Both amylose and amylopectin are rapidly hydrolyzed by the enzyme alpha amylase, which is secreted by the parotid glands and the pancreas. • Glycogen, like amylopectin, is a branched polymer of glucose. However, glycogen is more highly branched (with a-1,6 linkages) and very compact. It is especially abundant in the liver. Note: The glucose units of glycogen can enter the glycolytic pathway after removal by the action of glycogen phosphorylase. Note: The cleavage of glycogen beyond a branching point requires the activity of glucantransferase and amylo-alpha-1,6 glucosidase. Cellulose is the most common organic compound on earth. Cellulose is not digestible by hu¬mans and is often referred to as "dietary fiber" or "roughage," acting as a hydrophilic bulk¬ing agent for feces. The term glycan refers to a polysaccharide or an oligosaccharide.

The general term for reactions that prevent or minimize loss of blood from the vessels if they are injured or ruptured is: • Erythropoiesis • Syneresis • Homeostasis • Hemostasis

Hem ostasis Through a three-part process, the circulatory system guards against excessive blood loss. In this process, vascular injury activates a complex chain of events -¬vasoconstriction, platelet aggregation, and coagulation -- that leads to clotting. This process stops bleeding without stopping blood flow through the injured vessel. Three essential steps for blood clotting: 1. The production of thrombin from prothrombin during the clotting process requires a prothrombin activator, which is formed either by way of an extrinsic pathway or by way of an intrinsic pathway. A tissue factor (tissue thromboplast¬in) not normally present in the blood participates in the extrinsic pathway, but only factors present in the blood participate in the intrinsic pathway. 2. Prothrombin activator acts enzymatically to catalyze the formation of thrombin from prothrombin. 3. Thrombin acts as an enzyme to convert fibrinogen into fibrin threads that enmesh red blood cells and platelets to form the clot itself. 1. When blood vessels are ruptured and tissues are damaged, both the extrin¬sic and intrinsic pathways are usually activated. 2. In cirrhosis of the liver, prothrombin and fibrinogen levels will be defic¬ient and cause impaired clot formation. 3.Homeostasis - tendency toward equilibrium between different but inter¬dependent elements of an organism. 4. Erythropoiesis - the production of red blood cells. 5. Syneresis - liquid separating from a gel due to further solidification or coagulation.

Which of the following is considered to be the normal hemoglobin? )) • Hemoglobin H • Hemoglobin S • Hemoglobin M • Hemoglobin A • Hemoglobin C

Hemoglobin A Hemoglobin C is abnormal hemoglobin in which lysine has replaced glutamic acid, causing reduced plasticity of the red blood cells. Hemoglobin H is an abnormal hemoglobin composed of four beta chains; it is usually associated with a defect in three of the four alpha chain genes resulting in alpha-thalassemia. Hemoglobin S is an abnormal hemoglobin in which valine has replaced glutamic acid in the beta chain. The presence of hemoglobin S causes the red blood cell to deform and assume a sickle shape when exposed to decreased amounts of oxygen (such as might happen when someone exercises or in the peripheral circulation). Sickled red blood cells can block small blood vessels, causing pain and impaired circulation, decrease the oxygen-carrying capacity of the red blood cell, and decrease the cell's life span. Hemoglobin S is the predominant form of hemoglobin in persons with sickle-cell anemia. Important: A major effect of sickle cell anemia is the decreased solubility of the deoxy form of hemoglobin. Hemoglobin M is a group of abnormal hemoglobins in which a single amino acid substitution favors the formation of methemoglobin and is thus associated with methemoglobinemia.

All of the following will promote the release of oxygen from oxyhemoglobin --- the hemoglobin dissociation curve will shift to the right -- EXCEPT one. Which one is the EXCEPTION? • Increased carbon dioxide concentration (Pco2 • Increased tissue temperature • Increase in the pH • Increased diphosphoglycerate (DPG)

Increase in the pH - decrease in arterial hydrogen ion concentration *** This shifts the curve to the left. The influences of pH, Pco2, and temperature on the oxygen binding by hemoglobin (Hb) operates to ensure adequate deliveries of oxygen to active tissues. When a muscle is actively contracting, the following events occur: lactic acid is produced (lowering the pH), CO2 is produced by the tissues (thereby increasing Pco2), and heat is produced (thereby increasing tissue temperature). Therefore, the by-products of exercise are also the exact factors that stimulate 02 release from oxyhemoglobin. Active tissues have the following characteristics: • Lower pH. Note: Acidic conditions will decrease the affinity of Hb for 02. The higher the 11+ ion concentration (lower pH), the less 02 is bound to Hb. • Increased arterial Pco2. Note: The partial pressure of carbon dioxide (Pco2) affects the binding of 02 to Hb because carbon dioxide molecules bind with Hb molecules and alter the Hb molecule, thereby reducing their affinity for 02. Therefore, the higher the Pco2, the less 02 is bound to Hb. • Increased temperature. Note: The higher the temperature, the less 02 is bound to Hb at any given Po2. • Increased DPG. Note: Hypoxia increases the formation of DPG, which also shifts the oxyhemo¬globin dissociation curve to the right.

CNeural, mechanical, and hormonal factors affect the intensity of segmentation within the small intestine. For example, distension of the intestine by chyme and parasympathetic neural activity both the contractile force, while sympathetic neural activity it. } • Decrease, increases • Increase, decreases • Have no effect on, increases • None of the above

Increase, decreases Coordinated contractions of smooth muscle, called segmentation, participate in several ways to facilitate digestion and absorption in the small intestine: • Foodstuffs are mixed with digestive enzymes from the pancreas and bile salts from the biliary system. • Nutrient molecules in the lumen are constantly dispersed, allowing them to contact the epithelium, where enzymatic digestion is completed and absorption occurs. • Chyme is moved down the digestive tube, making way for the next load and eliminating undigestible, perhaps toxic, substances. Following a meal, when the lumen of the small intestine contains chyme, two types of motility predominate: segmentation contractions chop, mix, and roll the, chyme and peristalsis slowly propels the chyme toward the large intestine. 1. Chyme is the semifluid contents of the stomach consisting of partially Notes digested food and gastric secretions. 2. Gastric motility and emptying are influenced by distension of the stomach (via neural reflexes and gastrin) and by volume and composition of chyme in the duodenum (via enterogastric reflex and intestinal hormones).

Which two of the following will increase tissue edema? • Increased colloid osmotic pressure of the plasma • Increased colloid osmotic pressure of the interstitial fluid • Increased capillary fluid pressure • Increased interstitial fluid pressure

Increased capillary fluid pressure Increased colloid osmotic pressure of the interstitial fluid Capillary pressure is the pressure of the blood within the capillaries. Capillary pressure tends to force fluid out of the capillaries and into the tissue spaces by filtration through the capillary walls. Capillary pressure is determined by venous pressure and arterial pressure. The colloid osmotic pressure of the interstitial fluid tends to draw water out of the capillaries by osmosis. The interstitial fluid pressure is the pressure of the interstitial fluid, and it opposes the capillary pressure. This pressure tends to move fluid out of the tissue spaces and into the capillaries. The colloid osmotic pressure of the plasma (also called the oncotic pressure) opposes the colloid osmotic pressure of the interstitial fluid. This oncotic pressure tends to draw water into the capillaries by osmosis. An increase in capillary permeability (e.g., due to infection) can also result in tissue edema. Edema formation is reduced by lymphatic drainage of the interstitial space. Important: When the right ventricle weakens, fluid builds up in the peripheral tissues, leading to edema and liver engorgement.

Diabetes insipidus resembles diabetes mellitus because the symptoms of both diseases are: • Decreased urination and hunger • Increased urination and thirst • Decreased urinary output and weight gain • Increased urinary output and weight loss

Increased urination and thirst Diabetes insipidus is not the same as diabetes mellitus. Diabetes insipidus resembles diabetes mellitus because the symptoms of both diseases are increased urination and thirst. How¬ever, in every other respect, including the causes and treatment of the disorders, the diseases are completely unrelated. Sometimes diabetes insipidus is referred to as "water" diabetes to distinguish it from the more common diabetes mellitus or "sugar" diabetes. Diabetes insipidus (DI) is a disorder in which there is an abnormal increase in urine output, fluid intake, and often thirst. DI causes symptoms such as urinary frequency, nocturia (frequent awakening at night to urinate), or enuresis (involuntary urination during sleep or 'bedwet¬ting'). Urine output is increased because it is not concentrated normally. Consequently, in¬stead of being a yellow color, the urine is pale, colorless, or watery in appearance and the measured concentration (osmolality or specific gravity) is low. In diabetes insipidus (DI), there is a failure to either produce ADH (more common) or for the kidney to respond to ADH (rare). In DI, there is almost pure water loss, often with maintenance of normal sodium balance. In DI, the insufficient levels of antidiuretic hormone (ADH) cause excessive thirst (polydipsia) and excessive production of very dilute urine (polyuria). The normal action of ADH is to increase the reabsorption of water from the renal tubule, producing a smaller volume of concentrated urine. ADH is produced in the hypothalamus, and then stored and released into the bloodstream by the posterior pituitary gland in response to elevated plasma osmolarity. Important: Hypoactivity of the posterior pituitary gland or destruction of the supraoptic nuclei of the hypothalamus will result in diabetes insipidus. This deficiency of ADH results in failure of tubular reabsorption of water in the kidney and the consequent passage of a large amount of dilute urine and great thirst. Note: In diabetes insipidus, the body fluid volumes remain pretty close to normal so long as the person drinks enough water to make up for the increased clearance of water in the urine.

A competitive inhibitor of an enzyme: • Increases Km without affecting Vmax • Decreases Km without affecting Vmax • Increases Vmax without affecting Km • Decreases both Vmax and Km

Increases Km without affecting Vmax Competitive inhibition: • Inhibitor and substrate compete for the same binding site on the enzyme • Is overcome by increasing substrate • Vmax remains the same • Km is increased Noncompetitive inhibition: • Inhibitor and substrate bind at different sites on the enzyme • Is not overcome by increasing substrate • Vmax is decreased • Km is unchanged The rate at which an enzyme works is influenced by several factors: • The concentration of substrate molecules (the more of them available, the quicker the enzyme molecules collide and bind with them). The concentration of substrate is designated [S] and is expressed in unit of molarity. • The temperature: As the temperature rises, molecular motion and, hence, collisions between enzyme and substrate speed up. But as enzymes are proteins, there is an upper limit beyond which the enzyme becomes denatured and ineffective. • The presence of inhibitors (competitive and noncompetitive) • pH: The conformation of a protein is influenced by pH and as enzyme activity is crucially dependent on the protein's conformation, the enzyme's activity is likewise affected. 1. The velocity of a reaction increases with the substrate concentration if the enzyme concentration is constant. 2. At Vmax, all of the active sites are saturated with substrate.

Which of the following statements concerning the backbone of DNA are true EXCEPT one. Which one is the EXCEPTION? • It is constant throughout the molecule • It consists of deoxyriboses linked by "phosphodiester bridges" or "phosphodiester bonds" • It is hydrophobic • It is highly polar

It is hydrophobic *** This is false; it is hydrophilic. The backbone of DNA, which is constant throughout the molecule, consists of deoxyriboses linked by phosphodiester bonds. Note: The backbone of RNA consists of riboses linked by the same phosphodiester bonds. Specifically, the 5'-hydroxyl group of one nucleotide unit is joined to the 3'-hydroxyl group of the next nucleotide by a phosphodiester linkage. Thus, the covalent backbones of nucleic acids consist of alternating phosphate and pentose residues, and a purine or pyrimidine base is attached to each pentose. The 5'-OH group and the 3'-OH moiety are linked in a condensation reaction. Features of the DNA Double Helix: • Two DNA strands form a helical spiral, winding around a helix axis in a right-handed spiral. • The two polynucleotide chains run in opposite directions. • The sugar-phosphate backbones of the two DNA strands wind around the helix axis like the railing of a spiral staircase. • The bases of the individual nucleotides are on the inside of the helix, stacked on top of each other like the steps of a spiral staircase. 1. The backbones of both DNA and RNA are hydrophilic and highly polar. Notes 2. The hydroxyl groups of the sugar residues form hydrogen bonds with water. 3. The ribose phosphate portion of purine and pyrimidine nucleotides comes from 5-phosphoribosyl-l-pyrophosphate (PRPP). PRPP is synthesized from ATP and ribose 5-phosphate, which is primarily formed by the pentose phosphate pathway.

Erythropoietin is produced by , and has its primary action on the • Kidney, liver • Liver, kidney • Bone marrow, kidney • Kidney, bone marrow

Kidney, bone marrow Erythropoietin is a glycoprotein hormone produced in the kidneys that stimulates the production of red blood cells by bone marrow. The production of erythropoietin, and thus erythrocytes, is regulated by a negative-feedback mechanism that is sensitive to the amount of oxygen delivered to the tissues (particularly the kidneys). Anoxia (low oxygen) leads to greater production, while an increased oxygen supply leads to decreased production. The site of action of this hormone appears to be at the hemocytoblast (a pluripotent stem cell). Inadequate erythropoiesis leads to anemia, increased cardiac output, and hypoxia. Excessive erythropoiesis can lead to polycythemia, an increase in blood viscosity, and sluggish blood flow. Important: Anemic individuals have normal oxygen tension but reduced oxygen content in their systemic arterial blood. Characteristics of erythrocytes: 1. Biconcave discs, 7.5 microns in diameter, lack nuclei and mitochondria. 2. Contain hemoglobin. 3. Have a lipid membrane containing lipoproteins and specific blood group subst-ances (A, B, 0). 4. The principal function is to transport oxygen and carbon dioxide. 5. The proportion of erythrocytes in a sample of blood is called the hematocrit -¬- 46.2% for males and 40.6% for females is the normal range. 6. The amount of bile pigments excreted by the liver is a good indication of the amount of erythrocyte destruction per day. 7. Life span of erythrocytes = 105 to 120 days.

The immediate source of energy for muscle contraction is ATP binding to myosin. The ATP pool, however, is extremely small and has three sources of replenishment. Which of the following is not a source? • Creatine phosphate • Lactic acid • Glycogen • Cellular respiration

Lactic acid The hydrolysis of ATP (adenosine triphosphate) provides the immediate source of energy for muscle contraction. Although a muscle fiber contains only enough ATP to power a few twitches, its ATP "pool" is replenished as needed. The three sources of high-energy phosphate to keep the ATP "pool" filled are creatine phosphate, glycogen, and cellular respiration in the mitochondria of the muscle fibers. Creatine phosphate - The phosphate group in creatine phosphate is attached by a "high-energy" bond like that in ATP. Creatine phosphate derives its high-energy phosphate from ATP and can donate the phosphate back to ADP to form ATP. Creatine phosphate + ADP ++ creatine + ATP. The pool of creatine phosphate in the fiber is about 10 times larger than that of ATP and thus serves as a modest reservoir of ATP. Glycogen - Skeletal muscle fibers contain about 1% glycogen. The muscle fiber can degrade this glycogen by glycogenolysis, producing glucose- 1 -phosphate. This enters the glycolytic pathway to yield two molecules of ATP for each pair of lactic acid molecules produced. Not much, but enough to keep the muscle functioning if it fails to receive sufficient oxygen to meet its ATP needs by respiration. However, this source is limited, and eventually the muscle must depend on cellular respiration. Cellular respiration - Cellular respiration not only is required to meet the ATP needs of a muscle engaged in prolonged activity (thus causing more rapid and deeper breathing), but is also required afterwards to enable the body to resynthesize glycogen from the lactic acid produced earlier (deep breathing continues for a time after exercise is stopped). Note: The body must repay its oxygen debt.

Glucose, fructose, and galactose are classified as: • Monosaccharides • Disaccharides • Oligosaccharides • Polysaccharides

Monosaccharides The simplest of the carbohydrates are the monosaccharides, which can be classified according to the number of carbon atoms they contain. Those with three carbons are called trioses (for example, glyceraldehyde and dihydroxyacetone); four, tetroses (for example, erythrose); five, pentoses (for example, ribose); and six, hexoses (for example, glucose). Monosaccharides with an aldehyde as their most oxidized functional group are called aldoses (for example, glyceraldehyde); those with a keto group as their most oxidized functional group are called ketoses (for example, dihydroxyacetone). Remember: The naming of configurations of simple sugars (monosaccharides) and amino acids is based on the absolute configuration of glyceraldehyde. The symbols L and D refer to the absolute configuration of the four constituents around a specific chiral carbon (asymmetric carbon) in monosaccharides and amino acids. In a Fisher projection, the D form has the hydroxyl group on the right; the L form has the hydroxyl group on the left. Sugars of the D form, which are related to D¬glyceraldehyde, are the most common in nature. Other monosaccharides include: mannose, ribose, and xylose.

(?) , sometimes called vasogenic shock, results from the disruption of autonomic nervous system control over vasoconstriction. • Anaphylactic shock • Neurogenic • Cardiogenic shock • Hypovolemic shock

Neurogenic shock Shock is the collapse of the cardiovascular system, characterized by circulatory deficiency and the depression of vital functions. There are several types of shock: • Hypovolemic shock — caused by the loss of blood and other body fluids. • Neurogenic shock — caused by the failure of the nervous system to control the diame¬ter of blood vessels. • Cardiogenic shock — caused by the heart failing to pump blood adequately to all vital parts of the body. • Septic shock — caused by the presence of severe infection. • Anaphylactic shock — caused by a life-threatening reaction of the body to a sub-stance to which a patient is extremely allergic. Shock is the inadequate perfusion of tissue. The symptoms of shock include tiredness, sleepiness, and confusion. The skin becomes cold and sweaty and often bluish and pale. Other symptoms include tachypnea (rapid respiratory rate), hypotension (low blood pressure), and tachycardia (high pulse rate). The stages of shock: 1. Compensated: compensatory mechanisms (activation of the sympathetic nervous system, increased cardiac output, and increased total peripheral resistance) maintain perfusion to vital organs. 2. Progressive: decreased perfusion of the heart leads to cardiac depression and decreased cardiac output. 3.Irreversible: depletion of high-energy phosphate reserves. Death occurs even if treatment can restore blood flow.

The Michaelis constant, Km, is: • Independent of pH • Numerically equal to 1/2 Vmax • Dependent on the enzyme concentration • Numerically equal to the substrate concentration that gives half-maximal velocity

Numerically equal to the substrate concentration that gives half-maximal velocity This can be expressed as Km = [S], when Vo = 1/2 max *** Km is equivalent to that substrate concentration at which Vo (initial reaction velocity) is one-half Vmax. Note: Km has units of molarity. The Km values of enzymes range widely. For most enzymes, Km lies between 10-1 and 10-6 M. The Km value for an enzyme depends on the particular substrate and also on environmental conditions such as the temperature and ionic strength. The Michaelis constant (Km) is frequently, incorrectly, said to be equivalent to the dissociation constant of the enzyme-substrate complex. For most reactions, The Michaelis constant is a complex function of many different reaction constants, but this constant does give a means of comparison of the affinity (reciprocal of dissociation) of an enzyme for different substrates or different enzymes for the same substrate. The lower the Km the higher the relative affinity. 1. Km values for enzyme-substrate reactions: • Increase in the presence of a competitive inhibitor. • Are not affected in the presence of a noncompetitive inhibitor; however, V. is reduced. Important: The maximal rate (Vmax) is attained when the enzyme sites are saturated with substrate.

Which of the following globin chains are not commonly found in humans? ) • Alpha • Beta • Gamma • Omega

Omega A Molecule of Hemoglobin Is Composed of the Following: 1. Globin (protein) portion • Consists of four polypeptide chains - two alpha chains and two beta chains. • The normal adult globin portion of Hb consists of two alpha and two beta chains, and the normal fetal globin portion of Hb consists of two alpha and two gamma chains. 2. Four ring-shaped heme molecules (non proteingroups) • Each heme is a nitrogen-containing organic pigment molecule that has a single atom of iron in the reduced state (Fe2+ or ferrous iron) in its center, which can combine with one molecule of oxygen. These heme groups are attached to the globin polypeptide chains. Each iron atom can bind reversibly with one molecule of oxygen; therefore, a hemoglobin molecule can potentially associate with four oxygen molecules. When it is combined with oxygen, the compound is called oxyhemoglobin. When the hemoglobin molecule is not combined with oxygen, the compound is called deoxyhemoglobin (reduced 1. Hemoglobin combines reversibly with carbon dioxide at the protein Notes portion of the hemoglobin molecule. 2. Carbon monoxide decreases the amount of oxygen that can be transported by hemoglobin by competing with oxygen for hemoglobin binding sites. Carbon monoxide has a much higher affinity (240 x stronger) for hemoglobin than does oxygen. 3. As pH decreases, so does the affinity of hemoglobin for oxygen. 4. Methemoglobin contains iron in the ferric state (Fe") and cannot function as an oxygen carrier. 5. Hemoglobin is a major 11+ buffer of the blood. Deoxygenated hemoglobin is less acidic than oxygenated hemoglobin and therefore ideally suited to buffer the 1-1± ions (coming from tissue CO2).

Sugars that contain aldehyde groups that are (?) to carboxylic acids are classified as (?) sugars: • Oxidized, non-reducing • Oxidized, reducing • Reduced, non-reducing • Reducing, oxidizing

Oxidized, reducing *** Examples include: lactose, maltose, glucose, galactose, and fructose. Reducing sugars contain a free anomeric carbon (oxygen on CI atom is available for redox reaction) that can be oxidized. If the oxygen on the anomeric carbon (the carbonyl group) of a sugar is not attached to any other structure, that sugar is a reducing sugar. A reducing sugar can react with chemical reagents (see note #1 below) and reduce the reactive component. Note: The anomeric carbon itself becomes oxidized. Important point: This reaction is the basis of a reducing-sugar test, which was classically used by clinical laboratories to screen for diabetes (presence of excess free glucose in the blood) and other inborn errors involving the inability to metabolize other reducing sugars. Important: Most current clinical tests for blood glucose utilize glucose oxidase linked reactions. Because the reducing groups of both glucose and fructose are involved in the glycosidic bond, sucrose is not a reducing sugar. In other words, sucrose contains no free anomeric carbon. 1. Common test reagents are Benedict's reagent (CuSO4 /citrate) and Note! Fehling's reagent (CuSO4 /tartrate). They are classified as reducing sugars since they reduce the Cu" to Cut, which forms as a red precipitate, copper (I) oxide. 2. Glucosuria, the presence of glucose in the urine, can be caused by low insulin levels, high blood sugar levels, impaired tubular reabsorption, or a high glomerular filtration rate.

Which of the following is not a classification of an enzyme? • Oxidoreductase • Ligase • Transferase • Oxygenase • Hydrolase • Isomerase

Oxygenase Enzymes are catalysts. Most are very large proteins. Enzymes bind temporarily to one or more of the reactants of the reaction the enzymes catalyze. In doing so, they lower the amount of activation energy needed and thus speed up the reaction. The func¬tioning of the enzyme is determined by the shape of the protein. Enzymes are sub¬strate specific. For example, the enzyme peptidase (which breaks peptide bonds in proteins) will not work on starch (which is broken down by human producedamylase in the mouth). The arrangement of molecules on the enzyme produces an area known as the active site within which the specific substrate(s) will "fit." It recognizes, con¬fines, and orients the substrate in a particular direction. Classification of enzymes: • Oxidoreductases: catalyze a redox reaction • Transferases: transfer a functional group • Hydrolases: cause hydrolysis reactions • Lyases: break C-0, C-C, or C-N bonds • Isomerases : rearranges functional groups • Ligases: joins two molecules -- for example, DNA ligase joins pieces of DNA 1. Substrate concentration, pH, temperature, and enzyme concentration all have Notes an effect on the activity of an enzyme. 2. The enzymatic model that assumes that enzymes have flexible conforma-tions is called induced fit. 3. The inactive precursor of an enzyme is called a proenzyme. 4. A catalytically inactive protein formed by removal of the cofactor from an active enzyme is called an apoenzyme.

The principal hormone for calcium-level regulation is: • Calcitonin • Parathyroid hormone • Thyroid hormone • Vasopressin/antidiuretic hormone

Parathyroid hormone The human body contains 1-1.5 kg Ca2+, most of which (about 98%) is located in the mineral substance of the bone. The normal plasma concentration of calcium varies between 8.5 mg% and 10.5 mg%. Calcium levels are regulated by parathyroid hormone (PTH), which increases bone resorption and reabsorption of calcium in the kidney tubules, which in turn increases plasma calcium levels. Vitamin D3 regulates the uptake of calcium in the GI tract. Low serum calcium levels will result in hyperirritability of nerves and muscles. Patients with hyperparathyroidism will have increased renal calcium excretion and will also be predisposed to an increased likelihood of bone fracture. The bone resorption seen in elderly patients with low dietary calcium is intensified by parathyroid hormone. Calcium blood levels are increased in hypervitaminosis D, in hyperparathyroidism, and in bone cancer and other bone diseases. Calcium blood levels are decreased in severe diarrhea, in hypoparathyroidism, and in avitaminosis D (rickets and osteomalacia). Plasma phosphorus concentration (normal is approximately 4 mg%) is also regulated by parathyroid hormone. Increased hormone causes the kidneys to increase the rate of phosphate excretion, which decreases plasma phosphate concentration. Plasma glucose concentration (normal is approximately 100 mg%) is regulated by insulin (lowers glucose levels) and glucagon (increases glucose levels). Glucose normally does not appear in the urine although glucose is freely filtered because it is reabsorbed in the proximal convoluted tubule of the kidney (the renal threshold for glucose has not been exceeded). Important: The normal glucose clearance is 0 mg/min.

There are three major cells in the stomach that help to digest the food you ingest. There are four major secretions. Match the secretion to the cell that produces it. Cells Secretion • Parietal • Pepsinogen • Chief • Gastrin • G • HCL • Intrinsic factor

Parietal cells= HCI and Intrinsic factor Chief cells= Pepsinogen G cells= Gastrin Gastric pits are depressions in the epithelial lining of the stomach. At the bottom of each pit is one or more tubular gastric glands. Chief cells produce the enzymes of gastric juice, and parietal cells produce stomach acid. These glands produce as much as 2-3 liters of secretions per day. The pH of gastric secretion is 1.0-3.5. Note: The mucus produced by mucus-secreting cells is very alkaline and protects the stomach wall from being exposed to the highly acidic gastric secretion.

The activity level of which enzyme controls the rate of glycolysis? j • Aldolase • Phosphoglucose isomerase • Phosphofructokinase • Triose phosphate isomerase

Phosphofructokinase Phosphofructokinase (PFK) is a glycolytic enzyme that catalyzes the irreversible transfer of a phosphate from ATP to fructose-6-phosphate. This is the most important control point of glycolysis. Important point: The phosphofructokinase reaction is the rate-limiting step in glycolysis. The reaction, which is shown below, requires an input of energy from ATP. fructose-6-phosphate + ATP fructose-1,6-bisphosphate + ADP phosphofructokinase This allosteric enzyme is stimulated by ADP and AMP and is inhibited by ATP and citrate. In other words, the enzyme is most active when the energy of a cell is low. Fructose-2,6- bisphosphate is an important allosteric activator of this enzyme and an allosteric inhibitor of fructose-1,6-bisphosphatase, which physiologically reverses this reaction at the end of gluconeogenesis (glucose synthesis). Aldolase converts fructose-1,6-bisphosphate (6-carbon metabolite) into two 3-carbon metabolites, dihydroxyacetone phosphate and glyceraldehyde-3-phosphate. This is called the aldolytic reaction of glycolysis. Aldolase is plentiful in skeletal and heart muscle tissues. Glycolysis occurs in the cytoplasm in the absence of oxygen and involves the following: 1. Two molecules of ATP are used to phosphorylate glucose and start glycolysis. 2. The phosphorylated molecule is then broken down in a series of reactions into two, three carbon molecules (lysis). 3.Two molecules of NAD+ capture H and are reduced to 2 molecules of NADH . 4. Four molecules of ATP are produced by substrate phosphorylation. 5. The end product pyruvate may then either undergo aerobic respiration in the mito¬chondria or anaerobic respiration (fermentation). *** Net Gain of 2 ATP 1. Phosphoglucose isomerase catalyzes the isomerization of glucose-6-phosphate to Notes fructose-6-phosphate. 2. Triose phosphate isomerase interconverts dihydroxyacetone phosphate and glyceraldehyde-3 -phosphate.

Your patient has Alzheimer's disease and asks you about this new article read on blood clotting problems. He mentions that they talked of an enzyme that has been found to be deficient in AD patients. The lack of this enzyme would prevent him from dissolving clots at a normal rate. Appropriately enough, he forgot the name of this enzyme. Help this patient, by telling him what enzyme he is thinking of. • Prothrombin • Thrombin • Fibrinogen • Plasmin

Plasmin -- it is also called fibrinolysin Plasmin is normally present in the blood in an inactive form called plasminogen. Substances known as plasminogen activators (for example, urokinase produced in the kidney) can convert plasminogen to plasmin, which will cleave the peptide bond in fibrin, leading to its breakdown and dissolve clots. Fibrinogen is a soluble protein normally present in the plasma that is essential to the blood clotting process. Fibrinogen is converted into an insoluble, thread-like polymer called fibrin by the enzyme thrombin. Thrombin is produced from the inactive plasma protein precursor prothrombin, which is formed in the liver. In the presence of thromboplastin and calcium ions, prothrombin is converted to thrombin. Note: Research has shown that thrombin acts upon the arginyl-glycine linkages (specific peptide bonds) in fibrinogen to produce a fibrin monomer.

Which of the following enzymes is not involved in unwinding, unzipping, and rezipping the DNA molecule during replication? • Topoisomerases • Helicases • Gyrases • Polymerases

Polymerases *** Polymerases are used in replication itself. The hydrolysis of DNA (deoxyribonucleic acid) will yield: • Phosphoric acid • Deoxyribose (sugar) • Nitrogenous base (adenine, guanine, thymine, and cytosine) The hydrolysis of RNA (ribonucleic Acid) will yield: • Phosphoric acid • Ribose (sugar) • Nitrogenous bases (adenine, guanine, uracil, and cytosine) 1. Ribose and uracil are the only differences between the products of RNA and DNA hydrolysis. 2. DNA is double-stranded; RNA is single-stranded. 3. Replication forks are sites at which DNA synthesis (replication) is occur-ring. 4. Helicases unwind the helix. Topoisomerases are responsible for unwind-ing supercoiled DNA to allow DNA polymerase access to replicate the gen-etic code. The enzyme DNA gyrase re-forms the supercoiled structure once the replication fork has passed.

In your practice, you see quite a few HIV/AIDS patients. These patients have the unique ability in that they can: • Produce (+) ssRNA from a (—) ssRNA molecule • Produce (—) ssRNA from a (+) ssRNA molecule • Produce DNA from an mRNA molecule • Produce dsRNA from an ssRNA molecule

Produce DNA from a mRNA molecule *** Using the enzyme "reverse transcriptase" Reverse transcriptase is a DNA polymerase that uses RNA as its template. Thus, the enzyme is able to make genetic infolination flow in the reverse (RNA -- DNA) of its normal direction (DNA -- RNA). Certain RNA viruses contain within the viral particle a unique RNA-directed DNA polymerase that is called reverse transcriptase. On infection, the single-stranded RNA viral genome and the enzyme enter the host, and the reverse transcriptase catalyzes the synthesis of a DNA strand complementary to the viral RNA. Reverse transcriptase enzymes are found naturally in certain viruses called retroviruses. These are viruses in which the genetic information is carried on an RNA molecule. When one of these viruses infects a host cell, it uses this enzyme to make a complementary DNA (cDNA) copy of its genetic information, which is then incorporated into the host DNA. 1. The human immunodeficiency virus (HIV), the causative agent of AIDS, is a retrovirus. 2. The drug AZT (a thymidine analog) is a competitive inhibitor of the HIV reverse transcriptase. The wild-type reverse transcriptase seems to have a high affinity for AZT and other base analogs. 3. Reverse transcriptase is one of the enzymes used in genetic engineering, in which the enzyme can be used to obtain a copy of a particular gene from the relevant mRNA.

The ground substance of the extracellular matrix is made up of • Type II collagen • Type III collagen • Proteoglycan molecules • Fibrillin

Proteoglycan molecules - which are about 95% polysaccharide and 5% protein Proteoglycans consist of a core protein with glycosaminoglycans (GAGs) attached in a brush-like fashion. The linkage of GAGs to the core protein involves a specific trisaccharide composed of two galactose residues and one xylose residue. The protein cores are rich in serine and threonine residues, which allow multiple GAG attachments. Major functions include: lubricants, extracellular matrix, and being a molecular "sieve." Glycoproteins are proteins that have a carbohydrate covalently attached to them. The carbohydrate portion of most glycoproteins differs from that of proteoglycans in that it is shorter and branched. They serve as enzymes, hormones, antibodies, and structural proteins. Glycoproteins are often components of cell membranes and are involved in cell-to-cell interactions. Glycolipids (or sphingolipids) are found in the cell membrane with the carbohydrate portion extending into the extracellular space. They are derived from the lipid ceramide, and this class of compounds includes cerebrosides, globosides, and gangliosides.

All of the following are true of oxidative deamination reactions EXCEPT one. Which one is the EXCEPTION? • Provide a-ketoacids for energy • Provide ammonia for urea synthesis • Occur mainly in the liver and kidney • Provide a detoxification mechanism

Provide a detoxification mechanism Deamination is also an oxidative reaction that occurs under aerobic conditions in all tissues but especially the liver and kidneys. During oxidative deamination, an amino acid is con¬verted into the corresponding keto acid (for energy) by the removal of the amine functional group as ammonia and the amine functional group is replaced by the ketone group. The am¬monia eventually goes into the urea cycle. Oxidative deamination occurs primarily on glutamic acid because glutamic acid was the end product of many transamination reactions. Glutamate dehydrogenase is an enzyme of the oxidoreductase class that catalyzes the oxidative deamination of glutamate. Ammonia is released, and a-ketoglutarate is formed. Glutamate dehydrogenase is unusual in that it can use either NAD or NADP as a coenzyme. The reversible reaction has a major function in both the synthesis and degradation of glutamic acid and, via transaminases, other amino acids as well. *** Important: Both asparate aminotransferase (AST) and alanine aminotransferase (ALT) are transaminases (aminotransferases). They are not involved in oxidative deamination reactions. In contrast to transamination reactions that transfer amino groups, oxidative deamination results in the liberation of the amino group as free ammonia. 1. Glutaminase deaminates glutamine to glutamate and ammonium ion; asparaginase deaminates asparagine to aspartate and ammonium ion. 2. Glutamate is unique in that it is the only amino acid that undergoes rapid oxidative deamination. 3. Histidine is deaminated by histidase to form ammonium ion (NH+ ) and urocanate. 4. Serine and threonine are deaminated by serine dehydratase. Serine is converted to pyruvate, and threonine to a-ketobutyrate; ammonium ion is released.

A zymogen is converted to the active enzyme form through which of the following ways: • Removal of a peptide fragment • Addition of a peptide fragment • Addition of an amino group • Removal of an amino group

Removal of a peptide fragment Zymogens are enzymatically inactive precursors of proteolytic enzymes. The digestive enzymes that hydrolyze proteins are produced and secreted as zymogens in the stomach and pancreas. They are converted to their active forms by removal of a peptide fragment in the lumen of the digestive tract. Proteolytic enzymes, are synthesized as inactive zymogen precursors to prevent unwanted destruction of cellular proteins, and to regulate when and where enzyme activity occurs. Note: The release and activation of the pancreatic zymogens is mediated by the secretion of cholecystokinin and secretin. A good example of what occurs when some zymogens become active enzymes inside the cells is seen in acute pancreatitis, in which the premature activation of some of the pan-creatic enzymes, such as trypsin, phospholipase A2 and elastase, produce the autodiges-

Genetic recombination experiments depend heavily upon the action of which two enzymes? • Restriction endonucleases • Alkaline phosphatase • DNA ligases • Creatine kinase

Restriction endonucleases DNA ligases The nuclease is used to cleave both the DNA to be cloned and a plasmid DNA. The specificity of the nuclease is such that, when mixed, the DNA to be cloned and the plasmid DNA will anneal (base pair) and can then be joined together by a DNA ligase. Important point: Restriction enzymes are site-specific endonucleases. Southern blotting is a technique that can be used to detect mutations in DNA and can also identify DNA restriction fragments. It combines the use of restriction enzymes and DNA probes. Advances in this technology (DNA cloning) are revolutionizing many aspects of medicine, agriculture, and other industries. Commercial products of recombinant DNA technology include human insulin (for diabetes), anticoagulants (tissue plasminogen factor), erythropoietin (for anemia), and human growth hormone (for dwarfism). 1. The first organism used for DNA cloning was E. coli, and it is still the Notes most common host cell. Bacterial cloning vectors include plasmids, bacteriophages, and cosmids. 2. Some other enzymes that are used in recombinant DNA technology (gene cloning) are: • DNA polymerase I -- fills in the gaps in duplexes by step-wise addition of nucleotides to 3'-end. • Reverse transcriptase -- makes a DNA copy of an RNA molecule. • Exonucleases -- remove nucleotides from 3'-ends of a DNA strand.

Which material comprises most of the RNA in the cell? • Messenger RNA • Transfer RNA • Ribosomal RNA

Ribosomal RNA *** Transfer RNA is next, followed by messenger RNA. Types of RNA: 1. Messenger RNA (mRNA) molecules carry information (genetic code) from DNA in the nucleus to ribosomes in the cytoplasm, where polypeptides and proteins are synthesized (translation) -- mRNA is the template for protein synthesis and contains the codon. 2. Transfer RNA (tRNA) molecules carry the amino acids to ribosomes, where the amino acids are linked together in the order specified by mRNA to form particular polypeptides and proteins. Note: Amino acyl-tRNA synthetase is a group of ligases (enzymes) that ensures that the correct amino acid is attached to the tRNA with the correct anticodon to be used during protein synthesis. Individual enzymes are highly specific for one amino acid. No error checking occurs during the translation process on the ribosome. 3. Ribosomal RNA (rRNA) molecules are the major component of ribosomes, which are the physical and chemical structures on which protein molecules are actually assembled. Remember: Transcription is the process in which DNA serves as a template for the assembly of molecules of RNA (all three types). This process involves the enzyme RNA polymerase.

Which of the following blood equations is correct? • Serum = plasma - fibrinogen • Plasma = serum - fibrinogen • Serum = hematocrit + plasma • Hematocrit = fibrinogen - plasma

Serum = plasma - fibrinogen Human blood constitutes about 8% of the body's weight. Blood consists of cells and cell fragments in an aqueous medium, the blood plasma. The proportion of cellular elements, known as hematocrit, in the total volume is approximately 45%. The blood is the most important transport medium in the body. Blood maintains homeostasis and plays a decisive role in defending the body against pathogens. Serum is the clear, thin, and sticky fluid portion of the blood obtained after removal of the fibrin clot and blood cells. Serum differs from the plasma in that serum lacks fibrin and other coagulation products. Plasma is blood minus the formed elements. It is the fluid portion of the blood (plasma makes up 55% of the blood). Plasma also contains no cells. Plasma contains: • Proteins (7%) - consist of albumins, globulins, and fibrinogen. • Water (91%) • Other solutes (2%) - consist of metabolic end products, food materials, respiratory gases, hormones, and ions. - 1. Remember: The other 45% of the blood consists of formed elements ¬Notes'' erythrocytes (red blood cells), leukocytes (white blood cells), and thrombocytes (platelets). 2. The function of platelets in hemostasis is that they agglutinate and plug small ruptured vessels.

All reflex arcs have: • Three basic elements • Four basic elements • Five basic elements • Six basic elements

Six basic elements The reflex arc is a simple neural pathway connecting receptors to an effector. A receptor detects a stimulus or environmental change. An effector is an organ of response (i.e., skeletal muscle). It produces a response called a reflex. Reflexes are quick because they involve few neurons. Reflexes are either somatic (resulting in contraction of skeletal muscle) or autonomic (activation of smooth and cardiac muscle). All reflex arcs have six basic elements: a receptor, sensory (afferent) neuron, integration center (CNS), interneuron, motor (efferent) neuron, and effector. Spinal reflexes are somatic reflexes mediated by the spinal cord. Two important spinal reflexes influence the contraction of skeletal muscles. These are: 1. Stretch reflex - it is initiated at receptors called muscle spindles that are sensitive to muscle length and tension. This reflex stimulates the stretched muscle to contract. An example is the patellar reflex (knee jerk reflex), in which the striking of the patellar tendon at the knee causes the quadriceps muscles to contract and swing the lower leg forward. 2. Tendon reflex - it is initiated at receptors called neurotendinous organs (Golgi tendon organs) that are sensitive to tension that occurs as a result of muscular contraction or muscle stretch. This reflex stimulates the contracted muscle to relax. Note: When the stretch reflex stimulates the stretched muscle to contract, antag¬onistic muscles that oppose the contraction are inhibited. This occurrence is called reciprocal inhibition, and the neuronal mechanism that causes this reciprocal relationship is called reciprocal innervation.

The following list contains: Three (3) secretions from the enteric endocrine system that stimulate the pancreas Three (3) secretions from the pancreas acinar cells One (1) secretion from the pancreas duct cells Categorize them as to which ones are which: • Cholecystokinin • Amylase • Chymotrypsin • Trypsin • Secretin • Gastrin

Stimulators of the pancreas: Cholecystokinin, Secretin, Gastrin Pancreas acinar cell secretions: Amylase, Chymotrypsin, Trypsin Pancreas duct cell secretions: Bicarbonate ion Secretion from the exocrine pancreas is regulated by both neural and endocrine controls. During interdigestive periods, very little secretion takes place, but as food enters the stomach and, a little later, chyme flows into the small intestine, pancreatic secretion is strongly stimulated. Like the stomach, the pancreas is innervated by the vagus nerve, which applies a low-level stimulus to secretion in response to anticipation of a meal. Pancreatic secretions (daily secretion = 0.7-2.5; with a pH between 7.5 and 8.8) from pancreatic acinar cells include enzymes involved in protein breakdown (trypsin, chymotrypsin, and carboxypolypeptidase), carbohydrate breakdown (amylase), and fat breakdown (lipase, cholesterol esterase, phospholipase). Pancreatic enzymes are secreted in an inactive form called a zymogen, and are then activated in the small intestine. Note: Pancreatic duct cells secrete a fluid that is high in bicarbonate ion. The secretions of the exocrine gastric glands, composed of the mucous, parietal, and chief cells, make up the gastric juice (daily secretion 2-3 liters; with a pH between 1.0 and 3.0). Gastric secretions include HCL, mucus, pepsinogen, and intrinsic factor. Intestinal secretions (daily secretion unknown with a pH between 6.5 and 7.8), mainly mucus, are secreted by goblet cells and enterocytes. Bile (pH around 7.8) is produced by the liver and stored in the gallbladder. Bile aids in the emulsification, digestion, and absorption of fats. Cholecystokinin is a hormone produced by the wall of the upper part of the intestine. It stimulates the contraction of the gall bladder, releasing bile.

When a muscle is (?) the (?) reflex reacts. This reflex is considered (?) and the result is (?) • Contracted / Golgi tendon / monosynaptic / contraction • Stretched / Golgi tendon / disynaptic / relaxation • Stretched / stretch / monosynaptic / contraction • Contracted / stretch / disynaptic / relaxation • Stretched / stretch / monosynaptic / relaxation

Stretched / stretch / monosynaptic / relaxation The stretch reflex, also known as the myotatic reflex, responds to passive stretching of the muscle. The muscle stretch is detected by muscle spindles whose afferents (la fibers) synapse with lower motor neurons (a motor neurons) and interneurons (la inhibitory interneurons). The reflex is important for the automatic maintenance of posture and muscle tone. When the muscle is stretched, so is the muscle spindle. The muscle spindle depolarizes in response to stretching (senses the change in length) and sends action potentials to the spinal cord where it synapses with a motor neuron. This triggers the stretch reflex, causing the muscle to contract. The basic function of the muscle spindle is to convey information to the central nervous system concerning muscle length and tension. Important: The sensory receptors serving the stretch reflex are classified as proprioceptors. 1. The Golgi tendon reflex is the reverse of the stretch reflex. Golgi tendon Notes organs also depolarize in response to muscle stretch but inhibit the motor neuron, causing the muscle to relax. 2. The flexor-withdrawal reflex is a polysynaptic reflex that is used when a person touches a hot object or steps on a needle.

Which intestinal enzyme breaks down the 0-glycosidic bond between glucose and fructose? • Maltase • Lactase • Sucrase

Sucrase A disaccharide is a carbohydrate whose molecules contain two sugar units. Examples include: • Maltose ("beer sugar') - consists of two glucose molecules joined together by a reaction (condensation reaction) in which a molecule of water is removed. This reaction produces a bond between the two glucose molecules called a glycosidic bond. The intestinal enzyme maltase promotes the conversion of maltose into glucose. • Lactose ("milk sugar') - consists of glucose and galactose. The intestinal enzyme lactase promotes the conversion of lactose into glucose and galactose. • Sucrose ("table sugar') - consists of glucose and fructose. The intestinal enzyme sucrase (invertase) promotes the conversion of sucrose into glucose and fructose. Remember: The final digestion of these substances (disaccharides) to absorbable monosaccharides is completed by enzymes of the small intestine (maltase, sucrase, and lactase). These monosaccharides can then be absorbed by enterocytes. Monosaccharides can be linked by glycosidic bonds to create larger structures (disaccharides, oligosaccharides, and polysaccharides). These bonds form when the hydroxyl group on the anomeric carbon of a monosaccharide reacts with an —OH or —NH group of another compound (typically an alcohol, purine, pyrimidine, or in this case another sugar). Maltose, lactose, and sucrose consist of monosaccharides joined by an 0-glycosidic bond. 1. If oxygen is involved, this bond is classified as 0-glycosidic; if nitrogen Notes is involved, this bond is classified as N-glycosidic. 2. D-glucose is a monosaccharide, the most important of the aldohexoses.

All of the following statements concerning muscle spindles are true ----- 1 • They are found within the belly of muscles • They consist of small, encapsulated intrafusal fibers and run in parallel with the main muscle fibers (extrafusal fibers) • The finer the movement required, the smaller the number of muscle spindles in a muscle • They detect both static and dynamic changes in muscle length

The finer the movement required, the smaller the number of muscle spindles in muscle *** This is false; the finer the movement required, the greater the number of muscle spindles in a muscle. Muscle tone is "fine-tuned" by two sensory organs: 1. Muscle spindle (measures muscle length) - three components: 1. Specialized muscle fibers: (intrafusal fibers) 2. Sensory terminals: group Ia and II afferents 3. Motor terminals: gamma motor (efferent) neurons *** Activates alpha motor neuron when stretched. 2. Golgi tendon organ (measures muscle tension): innervated by a single-group Ib sensory (afferent) fiber. *** Inhibits alpha motor neuron. 1.The muscle spindle is a small, highly differentiated part of muscle tissue located within the belly of muscles and runs parallel with the main muscle fibers. 2. The annulospiral endings (sensory terminals) are wrapped around spec¬ialized muscle fibers that belong to the muscle spindle (intrafusal fibers) and are quite separate from the fibers that make up the bulk of the muscle (extrafusal fibers). 3. Motor (efferent) neurons can be further classified as alpha or gamma motor neurons. Alpha motor neurons innervate and stimulate skeletal muscle. Gamma motor neurons innervate the muscle spindle. 4. Activation of the gamma motor neuron maintains the spindle sensitivity.

CA patient comes to your office directly from an eye appointment. The ophthaN1- mologist has used tropicamide to induce mydriasis of the eye. What significance does this have on his or her dental appointment? • The patient will not be able to distinguish colors when you present him or her with the color choices for his or her dentures • The pupils are dilated, so the patient will be sensitive to the dental light if you don't control it well • The pupils are constricted, so the patient will have trouble seeing anything without high light • The patient has temporarily lost the ability to control his or her lenses, and so he or she will not be able to focus on anything

The pupils are dilated, so the patient will be sensitive to the dental light if you don't control it well. Remember: 1. Miosis is the constriction of the pupil of the eye. Miosis can be caused by a normal response to an increase in light, certain drugs, or pathological conditions. 2. Mydriasis is the prolonged abnormal dilation of the pupil of the eye induced by a drug or caused by a disease. In myopia (nearsightedness), the eye is too long for the refractive power of the lens, and far objects are focused at a point in front of the retina. The eye can focus on very near objects. This is caused by a cornea that is steeper, or an eye that is longer, than a normal eye. Nearsighted people typically see well up close but have difficulty seeing far away.To treat myopia, concave lenses are used. Farsightedness, or hyperopia, occurs when light entering the eye focuses behind the retina, instead of directly on it. This is caused by a cornea that is flatter, or an eye that is shorter, than a normal eye. Farsighted people usually have trouble seeing up close but may also have difficulty seeing far away as well. To treat hyperopia, convex lenses are used. Astigmatism occurs when the curvature of the lens is not uniform and is corrected with cylindric lenses. Presbyopia is the inability of the eye to focus sharply on nearby objects, resulting from the loss of elasticity of the lens with advancing age. Presbyopia is corrected with bifocals.

Which of the following are the same in RNA and DNA molecules? • The purines • The pyrimidines • Both the purines and pyrimidines • Neither the purines and pyrimidines

The purines *** The purines (A and G) are the same. In DNA, the pyrimidine bases are thymine (T) and cytosine (C). In RNA, the pyrimidine bases are uracil (U) and cytosine (C). *** The phrase "CUT down the pyramids" may help you remember that cytosine, uracil, and thymine are all pyrimidines. Remember: The backbone of the DNA molecule is constant throughout the entire molecule, and consists of the deoxyriboses linked by phosphodiester bridges (i.e., the 3'-OH group of the sugar of one is linked to the 5'-OH of the next sugar by a phosphate). The variable part of the DNA is the sequence of the bases, and the precise sequence of the purine and pyrimidine bases carry the genetic information to express the characteristics of the organism. The DNA chain has polarity with one end of the chain having a 5'-OH group while the other end has a 3'-OH group. 1. Purine bases that are consumed in the human diet in the form of DNA or RNA are mostly excreted in the form of uric acid. Xanthine oxidase catal¬yzes this formation of uric acid from purine bases. 2. The use of tetrahydrofolic acid (TFA) by several of the enzymes in pur¬ine and pyrimidine synthesis has made TFA metabolism a prime target for a number of antimetabolites, such as methotrexate, used in cancer chemo¬therapy. 3. Ultraviolet light produces pyrimidine dimers in DNA, which then inter¬feres with replication and transcription. These lesions are removed via the action of an exonuclease, an enzyme that excises a 12 by (base pair) frag¬ment surrounding the dimer. Then DNA polymerase I fills in the gap, and DNA ligase seals the seams.

All of the following statements about a person with type 1 diabetes mellitus are true EXCEPT one. Which one is the EXCEPTION? } • There is little or no insulin secretion • Dietary treatment may not suffice • There is hypoglycemia • Ketoacidosis and dehydration may develop

There is hypoglycemia *** This is false; there is hyperglycemia. Diabetes is a disease in which the body either fails to produce any insulin (type 1, also called insulin-dependent or juvenile-onset), or the insulin that the does produce is unable to ade¬quately trigger the conversion of food into energy (type 2, also called non-insulin-dependent or adult-onset). Symptoms of diabetes: • Excessive thirst • Frequent skin, bladder, or gum infections • Frequent urination • Irritability • Weight loss • Tingling or numbness in hands or feet • Blurred vision • Slow-to-heal wounds • Increased hunger • Extreme unexplained fatigue

Which Which of the following statements concerning glycosaminoglycans is true? • They contain branches of N-acetylneuraminic acid • They seldom contain sulfate groups • They are most often positively charged • They contain repeating disaccharides • They contain short oligosaccharide chains

They contain repeating disaccharides The most abundant heteropolysaccharides in the body are the glycosaminoglycans (GAGs). GAGs are long, linear carbohydrate chains that contain repeating disaccharide units, which usually contain a hexosamine and a uronic acid. GAGs often contain sulfate groups. The uronic acid and sulfate residues cause GAGs to be negatively charged. They are unbranched and do not contain N-acetylneuraminic acid. GAGs are highly negatively charged molecules, with extended conformation that imparts high viscosity to the solution. GAGs are located primarily on the surface of cells or in the extracellular matrix (ECM). Along with the high viscosity of GAGs comes low compressibility, which makes these molecules ideal for a lubricating fluid in the joints. At the same time, GAGs rigidity provides structural integrity to cells and provides passageways between cells, allowing for cell migration. 1. Glycosaminoglycans function as important structural components of connective tissue (which includes adipose tissue, cartilage, and bone as well as collagenous, elastic, and reticular fibers). Important: GAGs act as "molecular sponges" and hold water in the extracellular matrix. 2. Hyaluronic acid is unique among the GAGs in that it does not contain any sulfate and is not found covalently attached to proteins as are proteoglycans. 3. The majority of GAGs in the body are linked to core proteins, forming proteoglycans (also called mucopolysaccharides). 4. The bacterial cell wall contains a heteropolysaccharide made up of alternating N-acetylglucosamine and N-acetylmuramic acid units.

Which of the following is contained in a nucleoside? ) • Nitrogen base • Ribose/deoxyribose sugar • Phosphate • Two of the above • All of the above

Two of the above *** Nitrogen base and sugar. A nucleotide also contains the phosphate. A single base-sugar-phosphate unit is called a nucleotide. Without the phosphate group, the molecule is called a nucleoside. These individual nucleotides are linked together to form a polynucleotide chain (the link or bond is between a phosphate group of one nucleotide and the sugar of the next). If the polynucleotide chain contains the sugar ribose, the chain is called ribonucleic acid (RNA); if the contains the sugar deoxyribose, the chain is called deoxyribonucleic acid (DNA). Nucleic acids store and transmit information to synthesize the polypeptides and proteins present in the body's cells. Nucleic acids are complex molecules composed of structures known as nitrogenous bases (purines and pyrimidines), five-carbon sugars (pentoses), and phosphate groups (which contain phosphorus and oxygen). Important: The backbone of nucleic acids is made up of alternating phosphate and pentose units, with a purine or pyrimidine base attached to each. Remember: The catabolism of a nucleotide (single base-sugar-phosphate unit) results in no energy production in the form of ATP (as opposed to the catabolism of a lipid, protein, or carbohydrate, which does).

A sound wave will strike the first? ) • Membrane of the oval window • Membrane of the round window • Tectorial membrane • Tympanic membrane

Tympanic membrane Sound waves strike the tympanic membrane and cause it to vibrate. This causes the membrane of the oval window to vibrate, which causes the perilymph in the bony labyrinth of the cochlea and endolymph in the membranous labyrinth of the cochlea to move. This movement of the endolymph causes the basilar membrane to vibrate, which, in turn, stimulates hair cells on the organ of Corti to transmit nerve impulses along the cranial nerve. Eventually, nerve impulses reach the auditory cortex and are interpreted as sound. Parts of the Ear: External ear - consists of the external part (pinna) and the ear canal. • Auricle (pinna) - directs sound waves. • External auditory canal (meatus) - contains hair and cerumen (brown earwax); serves as a resonator. Middle ear (tympanic cavity) - an air-filled cavity in the temporal bone. • Auditory tube - equalizes pressure. • Ossicles (malleus, incus, stapes) - link together to transmit sounds to the oval win¬dow. Inner ear - formed by a membranous labyrinth within a bony labyrinth. • Vestibule (saccule and utricle) - associated with sense of balance. • Semicircular canals - concerned with equilibrium. • Cochlea (contains two membranes, vestibular and basilar) - portion of inner ear responsible for hearing. The spiral organ (organ of Corti) contains the receptors (called hair cells) for hearing. The cochlea is the basic functional unit of hearing because this portion transforms fluid vibrations from sound waves (mechanical energy) into a nerve impulse (electrical energy).

What is the substrate for glycogen synthesis? • UDP-glucose • TDP-glucose • ADP-glucose

UDP-glucose The synthesis of glycogen from glucose is carried out by the enzyme glycogen synthase. It is the key regulatory enzyme for glycogen synthesis and utilizes UDP-glucose as one substrate and the non-reducing end of glycogen as another. Note: Glycogen synthase is responsible for making the 1,4 linkages in glycogen. UDP-glucose is the substrate for glycogen synthesis. Glucose enters the cell and is phosphorylated to glucose-6-phosphate by hexokinase (in most tissues) or by glucokinase (in the liver). To initiate glycogen synthesis, the glucose-6-phosphate is reversibly converted into glucose- 1 -phosphate by phosphoglucomutase. This glucose-1- phosphate is then converted to UDP-glucose by the action of UDP-glucose pyrophosphorylase. 1. Glycogen synthase occurs in both phosphorylated and dephosphorylated Notes forms. The active enzyme, glycogen synthase, A is the dephosphorylated form. Glycogen synthase B is the phosphorylated form and is the inactive form of the enzyme. 2. Glycogen phosphorylase, which breaks down glycogen, also has two forms; (a) and (b); however, in this case the phosphorylation of this enzyme (which happens in liver cells) forms the active enzyme (a) and the dephos¬phorylation forms the inactive enzyme (b). Important: Both enzymes (glycogen synthase and phosphorylase) are phosphorylated at specific serine residues. 3. Until recently, the source of the first glycogen molecule that might act as a primer in glycogen synthesis was unknown. Recently, it has been discovered that a protein known as glycogenin is located at the core of glycogen molecules. Glycogenin has the unusual property of catalyzing its own glycosylation, attach¬ing C-1 of a UDP-glucose to a tyrosine residue on the enzyme. The attached glucose is believed to serve as the primer required by glycogen synthase.

0 blood type is referred to as: • Universal donor • Universal recipient • Neither of the above

Universal donor Type 0 people do not produce ABO antigens. Therefore, type 0 people's blood normally will not be rejected when it is given to others with different ABO types. As a result, type 0 people are universal donors for transfusions. AB-type people do not make any ABO antibodies. A-B type peolpe's blood does not discriminate against any other ABO type. Therefore, they are universal receivers for transfusions. All humans and many other primates can be typed by the ABO blood group. There are four types: A, B, AB, and 0. There are two antigens and two antibodies that are mostly responsible for the ABO types. The specific combination of these four components determines an individual's type. The table below (346) shows the possible permutations of antigens and antibodies with the corresponding ABO types ("yes" indicates the presence of a component, and "no" indicates its absence in the blood of an individual). For instance, type A people have the A antigen on the surface of their red cells (as shown in the table above). As a result, anti-A antibodies will not be produced because they would cause the destruction of their own blood. However, if B-type blood is injected into their systems, anti-B antibodies in the plasma will recognize the blood as alien and burst or agglutinate the introduced red cells in order to cleanse the blood of alien protein.

Iron, the most important mineral in the formation of hemoglobin, is resorbed mainly in the (?) and is only resorbed as (?) • Large intestine, Fe+3 • Large intestine, Fe+2 • Upper small intestine, Fe+3 • Upper small intestine, Fe+2

Upper small intestine (duodenum), Fe+2(ferrous, bivalent) Iron is quantitatively the most important trace element. The human body contains 4-5 grams of iron, which is almost exclusively present in protein-bound form. Approximately 75% of the total amount is found in heme proteins, mainly hemoglobin and myoglobin. In addition to hemoglobin and myoglobin, 15% to 25% of iron is stored in the liver, spleen, and bone marrow, mainly in the form of intracellular iron-protein complexes called ferritin and hemosiderin (a complex of ferritin, denatured ferritin, and other proteins). Iron is resorbed almost entirely in the upper part of the small intestine, primarily in the duodenum. Here iron immediately combines in the blood plasma with a beta globulin apotransferrin, to form transferrin, which is then transported in the plasma. Iron is bound loosely with transferrin and can be released to any of the tissue cells at any point in the body. Approximately 60% of excess iron is stored in the liver. The iron stored in ferritin is called storage iron. Important: Iron can only be resorbed by the bowel in bivalent form (i.e., as Fe+2). For this reason, reducing agents in food such as ascorbate (vitamin C) promote iron uptake. 1. The dominant factor controlling absorption of iron from the GI tract is Notes the saturation of mucosal cells with iron. 2. Hemochromatosis is an iron-storage disease that results in the deposition of iron-containing pigments in the peripheral tissues with cha-racteristic bronzing of the skin, diabetes, and weakness. 3. Bilirubin is a product of heme degradation.

Carbonic anhydrases are -containing enzymes that catalyze the reversible reaction between carbon dioxide hydration and bicarbonate dehydration. • Manganese • Selenium • Zinc • Mercury

Zinc Carbon dioxide (CO2) is a key metabolite in all living organisms. Carbon dioxide exists in equilibrium with bicarbonate (HCO3-), which is poorly soluble in lipid membranes compared to carbon dioxide; carbon dioxide can freely diffuse in and out of the cell, while bicarbonate must be transported. The conversion of bicarbonate to carbon dioxide facilitates its transport into the cell, while the conversion of carbon dioxide to bicarbonate helps trap the carbon diox¬ide in the cell. The interconversion of carbon dioxide and bicarbonate proceeds slowly at physiological pH, so organisms produce enzymes to speed up the process. Carbonic anhy¬drases are zinc-containing enzymes that catalyze the reversible reaction between carbon dioxide hydration and bicarbonate dehydration. Carbonic anhydrase catalyzes the following reaction: H2O + CO2 <---> HCO3- Carbonic anhydrase is one of the fastest known enzymes (one molecule of carbonic anhydrase can process one million molecules of CO2 each second) and is found in great concentration in erythrocytes. Carbonic anhydrase is an enzyme that enables red blood cells to transport carbon dioxide from the tissues to the lungs. 1. Within the erythrocyte, carbonic anhydrase facilitates the combination of carbon dioxide and water to form carbonic acid. 2. Carbonic anhydrase also functions in the kidney with the reabsorption of bicar¬bonate ion. 3. Although not required for carbon dioxide and water to form carbonic acid, carbonic anhydrase greatly increases the reaction in both respects (formation and dissociation). 4. Most of the carbon dioxide (CO) is transported in the blood as bicarbonate ion (HCO3) It is converted to carbonic acid (H2CO3) more rapidly in whole blood than in plasma. The reason for this is that whole blood contains erythro¬cytes with carbonic anhydrase while plasma does not contain erythrocytes.