Physiology/Biochem

reducing sugar

-any monosaccharide w/ a hemiacetal ring (since they can be oxidized, they are considered reducing agents) Glucose Maltose Lactose Galactose Fructose

Mean corpuscular hemoglobin

-hemoglobin amount per red blood cell -*measured in picograms (pg)*

D or L configuration

-look at the farthest chiral C away from the aldehyde -if OH is on the rt-- D -if OH is on the left--L

Hypotonic

A hypotonic solution has a lower concentration of solutes than another solution. In biology, a solution outside of a cell is called hypotonic if it has a lower concentration of solutes relative to the cytosol. Due to osmotic pressure, water diffuses into the cell, and the cell often appears turgid, or bloated.

All of the following hormones use adenylyl Cyclades-cAMP second messenger system:?

Adrenocorticotropic hormone (ACTH) Calcitonin Glucagon Somatostatin

Pentose Phosphate Pathway

A metabolic process that produces NADPH and ribose 5-phosphate for nucleotide synthesis.

Temporal lobe

A region of the cerebral cortex responsible for hearing and language.

occipital lobe

A region of the cerebral cortex that processes visual information

Which of the following RNA mutations is least likely to have a significant effect on the product protein?

A substitution of the third nucleotide of a codon due to the wobble effect 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

What does fluoride inhibit

Enolase Creates PEP

Which of the following processes is not involved in the formation of urine?

Excretion excretion - urine is excreted once it is formed, excretion is not part of formation

Mechanisms that the body uses to control the bloods acid bass balance

Excretion of carbon dioxide pH buffers are found in the blood Excess acid is excreted by the kidneys

Fast vs slow twitch muscle fibers

Fast twitch fibers are about twice as large in diameter than small twitch fibers Slow twitch fibers have a greater resistance to fatigue than fast twitch muscle fibers The enzymes of oxidative phosphorylation are considerably more active in slow twitch fibers than in fast twitch fibers Fast twitch fibers can deliver extreme amounts of power for a few seconds to a minute versus slow twitch fibers

As you complete the seating of a crown, you ask your patient to tap lightly on the articulating paper. Which of the following statements correctly describes the physiology responsible for a patient's light tapping on the articulating paper?

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 the muscle fibers that it innervates The size principle: motor units are recruited in order of the size of the motor unit. If only a small amount of tension is needed to perform a movement, then only small motor units will be activated. If greater force is required, more and large motor units will be recruited. Fractionation means that it is not necessary to activate all of the motor units in a muscle.

isotonic solution

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: A 0.9% solution of sodium chloride or a 5% glucose solution are both approximately isotonic to plasma.

oncogene

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 allele leads to unregulated growth. This is in contrast with tumor suppressor genes, in which both alleles must be defective 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 different 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 carcinomas and rhabdomyosarcoma Previous Flip Card Next

In your practice, you see quite a few HIV/ AIDS patients. These patients have a virus that has the unique ability to:?

Produce DNA from an mRNA molecule using the enzyme reverse transcriptase Reverse transcriptase is a DNA polymerase that uses RNA as its template Reverse transcriptase enzymes are found naturally in certain viruses called retroviruses

Products of COX pathway

Prostaglandins Prostacyclin Thromboxanes

Biotin is a prosthetic group of:?

Pyruvate carboxylase Acetyl-CoA carboxylase Propionyl-CoA carboxylase And other ATP-dependent carboxylases

Facts about the DNA backbone

It is highly polar It is constant throughout the molecule It consists of deoxyriboses linked by phosphodiester bridges or phosphodiester bonds It is hydrophilic

Characteristics of the pentose phosphate pathway

It produces CO2 It is controlled by the inhibition of the glucose 6 phosphate dehydrogenase by NADPH It produces ribose 5 phosphate It involves the breakage and formation of C-C bonds No ATP is consumed or produced in this cycle

Facts about heparin

It serves as a powerful anticoagulant 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 Small quantities are produced by basophil cells of the blood 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) It is usually in small concentrations in the blood Heparin is a naturally occurring sulfates glycosaminoglycan that is used to reduce clotting tendency of patients Inhibits the coagulation process by stimulating the inhibitor ANTITHROMBIN 3, in the absence of heparin, antithrombin 3 combines with several clotting factors, yielding complexes devoid of proteolytic activity's

Which of the following amino acids carry a positive charge on the side chain which makes them basic?

Lysine Histidine Arginine 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. 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 functions of amino acids in proteins are determined by the noncovalent interactions and the covalent bonds that their side chains can form: The small amino acids (glycine and alanine) occupy little space. In proteins they are often found in places where two polypeptide chains have to come close together. The branched-chain amino acids valine, leucine and isoleucine have hydrophobic side chains. The hydroxyl amino acids serine and threonine form hydrogen bonds with their hydroxyl group. This group also forms covalent bonds with carbohydrate in glycoproteins and with phosphate in phosphoproteins. The sulfur amino acids cysteine and methionine are quite hydrophobic, although cysteine also has weak acidic properties. The aromatic amino acids phenylalanine, tyrosine and tryptophan are hydrophobic, although the side chains of tyrosine and tryptophan can also form hydrogen bonds. The acidic amino acids glutamate and aspartate have a carboxyl group in the side chain that is negatively charged at pH 7. The corresponding carboxamide groups in glutamine and asparagine are not acidic but can form strong hydrogen bonds. The basic amino acids lysine, arginine and histidine carry a positive charge on the side chain, although the pK value of the histidine side chain is quite low. Proline is a freak among amino acids with its nitrogen tied into a ring structure as a secondary amino group. Being stiff and angled, it is often found at bends in the polypeptide.

glucose, fructose, and galactose are classified as?

Monosaccharides

myopia vs hyperopia

Myopia, or nearsightedness, occurs when an eye is larger than normal, causing it to be naturally focused up close. Reading vision is usually great without glasses but distance vision is blurred. The prefix "Hyper-" means "above", "higher", or" further". Hyperopia means "further out vision", or farsightedness.

Which of the following is the pace setting enzyme of glycolysis?

Phosphofructokinase

The common precursor of all three aromatic amino acids is:?

Chorismate Among the essential amino acids, the aromatic amino acids (phenylalanine, tyrosine, and tryptophan) form by a pathway in which CHORISMATE occupies a key branch point

By puncturing this artery, you have hit the vessel with the greatest:

Pressure

Which complex contains cytochromes b and C1 and an Fe-S center?

Complex 3

What contributes to intracellular edema?

Edema or swelling is the accumulation of excess fluid trapped in the body tissues. Most commonly edema occurs in the extracellular fluid compartment, but intracellular edema is also possible. Intracellular edema is defined as excess fluid accumulation in the intracellular spaces. It can occur in situations like hypotonic fluid overload, ischemia, or inflammation. Intracellular edema is caused by the following conditions: Hyponatremia due to a rapid reduction in the concentration of plasma sodium below normal (about 142 mEq/L). Depression of the metabolic systems of the tissues Lack of required nutrition to the body cells Inflammation that can increase cell membrane permeability Extracellular edema is a result of accumulation of fluid in the extracellular spaces. It can be caused by the following conditions: Abnormal leakage of capillary fluid to the interstitial spaces. Failure of the lymphatic function to return fluid from the interstitium back into the blood, as seen in lymphedema. Lymphedema may occur in case of cancer, surgery, certain infections, or absence of lymphatic vessels. Note: Excessive capillary fluid filtration is the most common clinical cause of accumulation of interstitial fluid. The factors that cause excess capillary fluid filtration are: Increased capillary filtration coefficient Increased capillary hydrostatic pressure Decreased plasma colloid osmotic pressure

Ketone

RCOR

Which process is most affected by levels of ADH?

Reabsorption

Reflexes have five basic elements

Sensory receptors Sensory afferent neurons Interneurons Motor efferent neurons Effector organs

nonreducing sugar

Sugars that cannot be oxidized because all anomeric carbons are involved in glycosidic bonds. Sucrose

reflexes of clinical importance are grouped into four types

Superficial reflexes: involves skin and the mucous membrane, corral and sneeze reflexes Deep tendon reflexes: myotatic reflexes: knee jerk or Achilles' tendon reflex Visceral or organic reflexes: accommodation reflex and bladder and rectal reflexes Abnormal or pathologically reflexes: babinski reflex which indicates a lesion of the corticospinal tract in adults

This drop in blood pressure will cause what to happen?

Sympathetic impulses to increase

Syneresis

Syneresis (also spelled 'synæresis' or 'synaeresis'), in chemistry, is the extraction or expulsion of a liquid from a gel, as when serum drains from a contracting clot of blood. Another example of syneresis is the collection of whey on the surface of yogurt.

Which of the following best describes an "uncompetitive inhibitor"?

essentially a noncompetitive inhibitor that can bind only when the substrate is attached

Which of the following equations correctly defines blood flow through the vasculature?

flow = (initial pressure - final pressure ) / resistance Blood flow is directly proportional to the pressure difference between the two ends of the vessel (the pressure gradient) and is inversely proportional to the resistance of the vessel. This relationship indicates that: the greater the pressure gradient , the greater the flow rate; and the flow rate decreases with increased resistance Factors influencing resistance are expressed as: 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 plays a key role in one carbon metabolism, and is essential for the biosynthesis of the purines and the pyrimidine, thymine?

folic acid Tetrahydrofolate's main function in metabolism is transporting single-carbon groups (i.e. a methyl group, methylene group, or formyl group). These carbon groups can be transferred to other molecules as part of the modification or biosynthesis of a variety of biological molecules. Folates are essential for the synthesis of DNA, the modification of DNA and RNA, the synthesis of methionine from homocysteine, and various other chemical reactions involved in cellular metabolism.[95] These reactions are collectively known as folate-mediated one-carbon metabolism.[8

Keratan sulfate

found in bone, cartilage, cornea of the eye Most heterogeneous GAG

The pitch of a sound is related mainly to which of the following characteristics of a 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

reduction

gain of electrons

Your patient's medical history says that she has von Gierke's disease. She is missing the enzyme ___________, which converts ___________.

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, is present 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.

Elastin has an aberrant amino acid composition, with high proportions of:

glycine, alanine and proline Elastin has high proportions of glycine (31%), alanine (22%), and proline (11%). Some hydroxyproline (1%; a derivative of proline) is also present, but there is no hydroxylysine. Like collagen, elastin contains covalent crosslinks that are derived from allysine. Therefore, lysyl oxidase is required for the synthesis of elastin as well as of collagen. The covalent crosslinks of elastin are similar to those of collagen except for desmosine, which is present in elastin but not collagen. 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.

allosteric enzymes

have both an active site for substrate binding and an allosteric site for binding of an allosteric effector (activator, inhibitor)

Gastrin

hormone secreted in the stomach that stimulates secretion of HCl and increases gastric motility Gastrin is a hormone that is produced by 'G' cells in the lining of the stomach and upper small intestine. During a meal, gastrin stimulates the stomach to release gastric acid. This allows the stomach to break down proteins swallowed as food and absorb certain vitamins.

The first heart sound ("Lub") is associated with the closure of the:

mitral and tricuspid 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. background image It is louder and longer than the second heart sound. Ventricular systole starts with the first heart sound. Ventricular diastole ends with the first heart sound. The second sound ("Dub") is associated with the closure of the semilunar valves (aortic and pulmonary 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. background image Diastole begins with the second heart sound. The aortic valve closes before the pulmonary valve; this causes "splitting" of the second heart sound.

Which of the following characteristics is shared by simple and facilitated diffusion of glucose?

occurs down an electrochemical gradient *** Both types of transport occur down an electrochemical gradient ("downhill") and do not require metabolic energy. 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 membrane. 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 required 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 (primary active transport) or another molecule with a favorable concentration gradient (secondary active transport; e.g., cotransporters and antiporters). 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 is regulated by insulin. Glut-5 transports fructose in the intestine and testis.

oxyntic cells

of or denoting the secretory cells which produce hydrochloric acid in the main part of the stomach, or the glands which they compose

PFK

rate limiting enzyme in glycolysis Fructose 6 phosphate ———-> fructose 1,6 bisphosphate

parietal lobe

receives sensory input for touch and body position

hypotonic solution

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.

Classification of enzymes: Oxidoreductases: catalyze redox reactions Transferases: transfer functional groups Hydrolases: cause hydrolysis reactions Lyases: break C-O, C-C, or C-N bonds Isomerases: rearrange functional groups Ligases: join two molecules, for example, DNA ligase joins pieces of DNA background image Substrate concentration, pH, temperature and enzyme concentration all have an effect on the activity of an enzyme. The enzymatic model that assumes that enzymes have flexible conformations is called induced fit. The inactive precursor of an enzyme is called a proenzyme. A catalytically inactive protein formed by removal of the cofactor from an active enzyme is called an apoenzyme.

Very true

Vitamins that can be taken with a risk of overdose:

Vitamin K 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

Vitamin B1 can be obtained from the diet by eating:

Yeast, lean pork, and legumes

Heparin

anticoagulant found in blood and tissue cells Also a GAG

Which of the following equations is correct?

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).

Brunner's glands

are found in the sub-mucosa of the duodenum and secrete alkaline mucous

Which structures are the site of highest resistance in the cardiovascular system?

arterioles

frontal lobe

associated with reasoning, planning, parts of speech, movement, emotions, and problem solving

Which type of RNA is least abundant?

mRNA Ribosomal rna is most abundant followed by transfer RNA

Which of the following functions as a coenzyme vital to tissue respiration?

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.

Your needle passed through the artery layers in which order?

tunica adventitia, tunica media, tunica intima

Spatial summation occurs when:

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: Spatial summation occurs when two excitatory inputs arrive at a postsynaptic neuron simultaneously. Together these two inputs produce greater depolarization. It is the result of a converging circuit and is dependent upon the simultaneous arrival of impulses from multiple presynaptic fibers. Temporal summation occurs when two excitatory inputs arrive at a postsynaptic 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. Previous Flip Card Next

Your dental assistant comes in all smiles, she said she's prego, you recommend to keep this mineral high because it helps her immune system. she often comes in w/ loads of perfume 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? -phosphorus -cobalt -copper -zinc

zinc (most abundant trace mineral besides iron) Zinc supports a healthy immune system, wound healing, and helps maintain sense of smell. It is also important for DNA synthesis.

All amino acids have a carboxyl group and an amino group, both bound to the same carbon. This carbon is called the:

α-carbon

Which of the following represents the pH of a solution that has a 10^-4 concentration of OH ion?

10

For the following questions, use the same answer choices. Which of the following has the thickest layer of muscle? Which of the following is the major regulator of blood flow? Which of the following contain valves? Which of the following are large vessels that contain deoxygenated blood? Is there an EXCEPTION to this rule? Which has higher compliance, veins or arteries?

1. arteries 2. arterioles 3. veins 4. 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. These 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 deoxygenated blood. Systemic veins - function as conduits for the transport of deoxygenated 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 and umbilical 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 coalesce into progressively larger veins.

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?

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. 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. 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 of the lungs. Note: The volume of blood flow per minute (5 L/min) is the same in both circuits. Remember: Mean arterial blood pressure = Cardiac output × Total peripheral resistance Vascular compliance = Increase in Volume/Increase in pressure 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.

A sequence of DNA reads A-T-T-G-C-A. how many hydrogen bonds would you expect to see holding its sequence in complimentary strand?

14 (2 in each AT pairing and 3 in each GC)

Which of the following solutions has an osmotic pressure different from the other two solutions?

1M 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.

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. The overall electron chain transport reaction is:?

2 Hydrogens + 2 electrons + 1/2 Oxygen —-> H2O + energy (ATP) The majority of the energy conserved during catabolism reactions occurs near the end of the metabolic series of reactions in the electron transport chain. Notice that 2 hydrogen ions, 2 electrons and an oxygen molecule react to form as a product water with energy released in an exothermic reaction. This relatively straight forward reaction actually requires eight or more steps. The energy released is coupled with the formation of three ATP molecules per every use of the electron transport chain

Theoretically in most human cells, one glucose molecule produces enough usable chemical energy to synthesize:?

36-38 ATP

chiral carbon

A carbon atom attached to four different atoms or groups of atoms.

prosthetic group

A cofactor or coenzyme that is covalently bonded to a protein to permit its function

Para-aminohippuric acid (PAH)

A small organic chemical (N-(4-aminobenzoyl)glycine) which may be used as a biological marker in certain renal function studies because it is transported from the blood to the urine by toxin pumps in the renal tubule, an example of renal tubular secretion; - it is generally used to assess the adequacy of renal perfusion (blood flow to the nephrons). It is informative to contrast the properties of inulin with those of para-aminohippuric acid (PAH). PAH is partially filtered from plasma at the glomerulus and not reabsorbed by the tubules, in a manner identical to inulin. PAH is different from inulin in that the fraction of PAH that bypasses the glomerulus and enters the nephron's tubular cells (via the peritubular capillaries) is completely secreted. Renal clearance of PAH is thus useful in calculation of renal plasma flow (RPF), which empirically is (1-hematocrit) times renal blood flow. Of note, the clearance of PAH is reflective only of RPF to portions of the kidney that deal with urine formation, and, thus, underestimates the actual RPF by about 10%.[34]

Benedict's test

A test for the presence of reducing sugars. The appearance of a red precipitate from the original blue dye indicates the presence of REDUCING SUGARS and thus could also indicate kidney problems in the case of excess reducing sugars being found in the urine. Benedict's reagent (often called Benedict's qualitative solution or Benedict's solution) is a chemical reagent and complex mixture of sodium carbonate, sodium citrate and copper(II) sulfate pentahydrate.[1] It is often used in place of Fehling's solution to detect the presence of reducing sugars. The presence of other reducing substances also gives a positive result.[2] Such tests that use this reagent are called the Benedict's tests. A positive test with Benedict's reagent is shown by a color change from clear blue to brick-red with a precipitate.

A sequence of DNA is "TAGTATCAT. What is the complementary RNA sequence?

AUCAUAGUA

As an action potentiometer reaches a skeletal muscle cell, what is the order of activation by which the signal is transmitted internally through the muscle cell so that contraction results?

Acetylcholine Calcium Troponin Tropomyosin Myosin heads When an action potential arrives at a muscle cell, the action potential causes calcium to be released from the sarcoplasmic reticulum. As calcium is increased it begins to bind to troponin C. After calcium binds with troponin, tropomyosin moves from its blocking position, permitting actin and myosin to interact

Strictly speaking, the all-or-none principle refers to the:

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 potential 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.

Which of the following is the enzyme that produces two distinct carbon based molecules?

Aldolase

ADH also called vasopressin and oxytocin are synthesized in neuroendocrine cells located within the SUPRAOPTIC and PARAVENTRICULAR NUCLEI of the hypothalamus. The synthesized hormones are packaged in granules that are transported down the axon of the cell and stored in nerve terminals located in the NEUROHYPOPHYSIS (posterior pituitary) ADH is formed primarily in the SUPRAOPTIC NUCLEI and oxytocin is formed primarily in the PARAVENTRICULAR NUCLEI of the hypothalamus ADH increases the water permeability of the collecting ducts and distal tubules. Without ADH, there would be extreme loss of water into the urine

All are true

Cellulose is an unbranched polymer of glucose residues bonded by B 1,4 linkages and it is the main component of the plant cell wall. Dextrin are the intermediated produced during the hydrolysis of starch. Chitin is a structural polysaccharide found in the exoskeleton of arthropods Pectin is a polymer of galactouronic acid found in fruits

All are true

Growth hormone is also called SOMATOTTROPHIC HORMONE or SOMATOTROPIN, and is synthesized and secreted by cells called somatotropes Growth hormone stimulates body growth, secretion of IGF-1 and lipolysis; it however inhibits the actions of insulin on carbohydrate and lipid metabolism A major target of growth hormone is the liver, where it causes the liver to form several small proteins called somatomedins that have the potent effect of increasing al aspects of bone growth Somatomedins are also known as insulin like growth factors due to the similar effects of insulin on growth Excessive growth hormone can lead to gigantism and acromegaly, (Acromegaly is a disorder that results from excess growth hormone (GH) after the growth plates have closed)

All are true

Peripheral nerve fibers can sometimes regenerate if the soma or cell body is not damaged and some of the neurilemma remains intact The neurilemma forms a regeneration tube through which the growing axon reestablishes 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 reestablished Nerve fibers of the brain and spinal cord are are not enclosed by a neurilemma. This is why regeneration of severed axons is more difficult in the CNS (brain and spinal cord).

All are true

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 Rods are more abundant than cones The retina is the innermost layer of the eye

All are true

Testosterone and pituitary follicle simulating hormone are required for normal sperm production Only seretoli cells express the androgen receptor and the FSH receptors, so these hormones regulate spermatogenesis indirectly through their actions on Sertoli cells

All are true

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.

All are true

The stomach mucosa consists of two important types of tubular glands namely oxyntic glands and pyloric glands Oxyntic glands are composed of: Mucous neck cells which secrete mainly mucus Chief cells which secrete pepsinogen, an inactive precursor of pepsin Pyloric glands are composed of G cells which secrete gastrin

All are true

Vitamin K deficiency most like occurs in newborns. Humans get some of their Vitamin K as PHYLLOQUINONE and some as MENAQUINONE produced by intestinal bacteria Unlike the other fat soluble vitamins, vitamin k is not stored to any great extent

All are true

When blood is centrifuged in the presence of anticoagulant, blood cells account for 40-50% of the total volume, and the remainder yellowish fluid is called PLASMA. Besides water, plasma contains 0.9% inorganic ions, 7% protein, and 0.8% other organic molecules. The major PLASMA proteins are albumin, globulins, fibrinogen, and blood clotting factors. Most plasma proteins except ALBUMIN are glycoproteins Albumin is one of the most hydrophilic proteins

All are true

Common subunit hemoglobin chains:?

Alpha Beta Gamma Delta A molecule of hemoglobin is composed of the following: Globin: Consists of four polypeptide chains: two alpha and two beta chains (for adults) The normal fetal globin portion of Hb consists of two alpha and two gamma chains Four ring shaped heme molecules (non protein groups) Each heme is a nitrogen containing organic pigment molecule that has a single atom of iron in the reduced state (Fe+2 or ferrous iron) in its center, which can combine with one molecule of oxygen.

Weak bonds are involved in all the following except?

Amino acid linkage

Ammonia is produced from the metabolism of a variety of compounds. 1. Which compound listed below is quantitatively the most important source of ammonia?

Ammonia From amino acids: many tissues, but particularly the liver, form ammonia from amino acids by the aminotransferase and glutamate dehydrogenase reactions.

Which of the following are the main constituents of starch?

Amylopectin and amylose The main storage of polysaccharides are: Starch in plants Glycogen in animals The two main constituents of starch are amylose and mainly amylopectin. Amylopectin has alpha 1,4 and alpha 1,6 linkages. Amylose simply has alpha 1,4 linkages.

intrafusal fibers

Are encapsulated in sheaths to form muscle spindles Innervated by gamma motor neurons (efferent) Two types of intrafusal fibers Nuclear bag fibers Detect fast, dynamic changes in muscle length and tension Innervated by group Ia afferents: fastest in the body Nuclear chain fibers Detect static changes in muscle length and tension Innervated by the slower group II afferents as well as the group Ia afferents

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:

Arginine and lysine The histone proteins consist of five classes, namely H1, H2A, H2B, H3, and H4. These proteins are rich in positively charged basic amino acids-lysine and arginine. These positively charges reduce electrostatic repulsion by attracting negatively-charged phosphate groups of DNA forming a tighter DNA packing. 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. background image Chromatin also contains small amounts of a wide variety of nonhistone proteins. Most of these are transcription factors (e.g., the steroid receptors) and their association with the DNA is more transient. Activation of DNA for replication or transcription requires breakup of the nucleosome structure. Phosphorylation of histone serine and threonine residues is part of the process for replication, while acetylation of histone lysine residues is used for transcriptional activation.

Which of the following factors has no direct effect on pulmonary ventilation?

Arterial [HCO3] Pulmonary ventilation is the total volume of gas per minute, inspired or expired. HCO3 does not directly affect pulmonary ventilation. HCO3 does have influence, but that is through pH and H+. There are no HCO3 sensors Peripheral chemoreceptors located in the carotid and aortic bodies receives stimuli that increases breathing rate including PO2, PCO2, and pH Central chemoreceptors are located in the medulla. The medulla has H+ receptors and H+ concentrations controlled by diffusion of CO2 through the blood nemesis barrier and conversion to H+ and HCO3; so PCO2 indirectly stimulates central chemoreceptors

Glutamate can be synthesized by the addition of ammonia to α-ketoglutarate. All of the following amino acids can be derived from glutamate EXCEPT one. Which one is the EXCEPTION?

Asparginine α-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.

Isotopes of an element:

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 Previous Flip Card Next

water soluble vitamins

B vitamins and vitamin C

Which one of the following reflexes is the atrial reflex that controls the heart rate?

Bainbridge reflex The Bainbridge reflex or atrial reflex is a neural reflex of increasing heart rate in response to an increase in central venous pressure and atrial volume. Stretch receptors located in both atria initiate the Bainbridge reflex by transmitting afferent signals through the vagus nerves to the medulla of the brain. Then efferent signals are transmitted back through vagal and sympathetic nerves to increase the heart rate and strength of heart contraction. Thus, this reflex helps prevent pooling of blood in the veins, atria, and pulmonary circulation. Note: The baroreceptor reflex system works to maintain arterial blood pressure at constant levels. Baroreceptors are stretch receptors present in the carotid arteries and aortic arch. The baroreceptors detect changes in blood pressure and signal to the brain to increase or decrease the cardiac output (heart rate and inotropy) and peripheral resistance accordingly so as to keep pressure constant. Changes in heart rate induced by a change in blood volume are controlled by the combined actions of the Bainbridge and baroreceptor reflexes. When the heart rate is low, an intravenous infusion increases the heart rate via the Bainbridge reflex. However, when the heart rate is high, an intravenous infusion invokes both of these reflexes and the resulting effect is a slowing of the heart rate. The regulation of heart rate is controlled by the following mechanisms: • The baroreceptors and autonomic nervous system • The Bainbridge reflex • The chemoreceptor reflexes • The ventricular receptor reflexes • The thoracic pressure changes brought upon on respiration on venous return

Which of the following structures plays a role by associating with the corticospinal system to control complex patterns of motor activity?

Basal ganglia

A patient of yours presents with symptoms similar to Parkinson's disease. He 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?

Basal ganglia The basal ganglia include several deep telencephalic nuclei (including the caudate nucleus, putamen, and globus pallidus). The basal ganglia interacts with the cerebral cortex, subthalamic nucleus, substantia nigra, and thalamus. 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 and Huntington's disease, the person has unwanted movements, such as involuntary jerking movements of an arm or leg or spasmodic movement of facial muscles. The term striatum, derived from the striated appearance of these nuclei, refers only to the caudate nucleus and putamen. The striations are produced by the fiber bundles formed by the anterior limb of the internal capsule, as it separates the caudate nucleus and putamen. The combination of putamen and globus pallidus is often referred to as the lentiform 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. This communication occurs via two opposing pathways → a direct and an indirect path both which use dopamine as a neurotransmitter. Dopamine is inhibitory in the indirect path and excitatory in the direct path with an overall net excitatory role. The basal ganglia are located deep into 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).

Which of the following is a severe thiamine-deficiency syndrome found in areas where polished rice is the major component of the diet?

Beri beri Beriberi is a disease in which the body doesn't have enough vitamin B-1 (thiamin). Deficiency results in severe muscle weakness and wasting away Risk factors include a diet of mostly white rice, as well as alcoholism, dialysis, chronic diarrhea, and taking high doses of diuretics Thiamine in the human body has a half-life of 18 days and is quickly exhausted, particularly when metabolic demands exceed intake. A derivative of thiamine, thiamine pyrophosphate (TPP), is a cofactor involved in the citric acid cycle, as well as connecting the breakdown of sugars with the citric acid cycle. The citric acid cycle is a central metabolic pathway involved in the regulation of carbohydrate, lipid, and amino acid metabolism, and its disruption due to thiamine deficiency inhibits the production of many molecules including the neurotransmitters glutamic acid and GABA.[36] Additionally thiamine may also be directly involved in neuromodulation.[3

Side effects of excess fluoride intake:

Bone fracture (fluoride in high concentration increases the risk of stress fractures by impairing mineralization of the enamel Mottled (spots on) enamel GI tract damage Fluoride helps in prevention of dental caries as it increases the resistance of the enamel against degradation by microbial acids. It strengthens enamel by hardening and stabilizing the enamel matrix, which is calcium phosphate based.

Carbonic acid/ bicarbonate is the most important physiological buffer system in the body Proteins also participate in pH buffering, mainly through histidine side chains

Both are true Hemoglobin is a major intracellular buffer

oxidative phosphorylation is the major source of ATP in aerobic organisms The generation of GTP from succinyl CoA is an example of substrate level phosphorylation in which the production of high energy phosphate is coupled to the conversion of substrate to product, rather than resulting from oxidative phosphorylation

Both are True

All the major anterior pituitary hormones except for growth hormone exert their principal effects by stimulating target glands such as the thyroid gland, adrenal cortex, ovaries, testicles, and mammary glands. Growth hormone, in contrast to other hormones, does not function through a target cell but exerts its effects directly on all or almost all tissues of the body

Both are true

Cholecalciferol is not the active form of vitamin D and needs to be converted to active 1,2,5-dihydroxycholecalciferol (calcitriol) by successive hydroxylations in the liver and kidney Vitamin D is nutritionally essential only for people who stay out of the sun

Both are true

Glucagon, a hormone secreted by the alpha cells of the islets of langerhaans when blood glucose concentration falls, has several functions that are diametrically opposed to those of insulin The most important function of glucagon is to increase the blood glucose concentration, an effect that is exactly the opposite of insulin.

Both are true

Increasing hematocrit results in increased blood viscosity. The viscosity of plasma is about 1.5 times that of water.

Both are true

Km is the substrate concentration at which the enzyme is half-saturated with its substrate. Km is also the substrate concentration at which the reaction is half maximal.

Both are true

Membrane proteins are globular proteins Proteins account for about one half of the total mass in most membranes

Both are true

Replication is the process of completely duplicating the DNA within a cell. The primary enzyme in the process is DNA polymerase, which reads a single stand of DNA from the 3 end toward the 5 end while forming the new complementary continuous stand from the 5 end towards the 3 end RNA intermediates are involved to prime the DNA polymerase and then are later replaced by DNA

Both are true

The collagen fibers provide bone with great tensile strength, while the inorganic salts allow bone to withstand compression. 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.

Both are true

The first half of the monthly menstrual cycle is referred to as the follicular phase of the ovary. The second half of the monthly menstrual cycle is known as the luteal phase of the ovary. This phase is dominated by hormonal secretions of the corpus luteum.

Both are true

The liver synthesizes all of the so-called nonessential amino acids The liver plays an important role in glucose metabolism by engaging in gluconeogenesis

Both are true

There are two major groups of descending tracts from the brain: the corticospinal, or pyramidal tracts, and the extrapyramidal tracts. The pyramidal tracts descend directly without synaptic interruption, from the cerebral cortex to the spinal cord.

Both are true

arachidonic acid an unsaturated fatty acid is the major compound from which prostaglandins, prostacyclin, thromboxanes, and leukotrienes are derived To form leukotrienes the lipoxygenase pathway utilizes the enzyme lipoxygenase

Both are true

dextrans are polysaccharides of glucose produced extracellually by bacteria and yeast The enzyme used to produce dextrans is glucosyl transferase (dextran sucrase) and the substrate sucrose A side product of dextran production is fructose which is formed into levans (fructans) and stored intracellularly as reserve nutrients Streptococcus mutans can produce dextran from sucrose. Dextran is sticky and contributes to the cariogencity of Streptococcus mutans

Both are true

The nonessential amino acids are synthesized either from common metabolic intermediates or from other amino acids. Only leucine and lysine are purely ketogenic.

Both are true Amino acids can also be classified as ketogenic, glucogenic, or both according to the nature of their metabolic end products. The seven amino acids (phenylalanine, tyrosine, isoleucine, leucine, tryptophan, threonine and lysine) that are degraded entirely or in part to acetoacetyl-CoA and/or acetyl-CoA can yield ketone bodies in the liver, where acetoacetyl-Co-A is converted to acetoacetate and then to acetone and β-hydroxybutyrate. These are the ketogenic amino acids. The amino acids that are degraded to pyruvate, α-ketoglutarate, succinyl-CoA, fumarate, and/or oxaloacetate can be converted to glucose and glycogen. They are the glucogenic amino acids. Note: The division between ketogenic and glucogenic amino acids is not sharp, five amino acids (tryptophan, phenylalanine, tyrosine, threonine and isoleucine) are both ketogenic and glucogenic. Only leucine and lysine are purely ketogenic.

. The primary physiological control of the salivary glands is by the parasympathetic nervous system. Control of salivary secretion is exclusively neural.

Both are true Control of salivary secretion is exclusively neural. In contrast, control of most other GI secretions is primarily hormonal.

Both hemoglobin in RBCs and myoglobin in the muscles employ heme as a prosthetic group. Myoglobin consists of a single polypeptide with a noncovalently bound heme group while hemoglobin has four polypeptides, each with its own heme.

Both are true Humans need oxygen-binding proteins because molecular oxygen is poorly soluble in body fluids. The functions of oxygen transport from lungs to the tissues and oxygen storage in tissues are carried out by the homologous heme proteins, hemoglobin and myoglobin respectively. Both hemoglobin in RBCs and myoglobin in the skeletal muscles employ heme as a prosthetic group (type of cofactor that is tightly bound to an enzyme and required for biological activity). Myoglobin consists of a single polypeptide with a noncovalently bound heme group while hemoglobin has four polypeptides, each with its own heme. Adult hemoglobin (HbA) has two alpha chains and two beta chains and fetal hemoglobin (HbF) has two alpha chains and two gamma chains. 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 hemoglobin at low pO2. This makes myoglobin well suited for its biological function within muscle cells, which is to store oxygen and make it available to the mitochondria at the time of oxygen deprivation such as during strenuous exercise. Important: The heme iron in hemoglobin and myoglobin binds molecular oxygen only in the ferrous (Fe2+) state. Its oxidation to the ferric (Fe3+) form produces useless methemoglobin. The enzyme methemoglobin reductase reduces methemoglobin back to normal hemoglobin, using the coenzyme NADH as a reductant.

The temperature of the body is regulated by neural feedback mechanisms that operate primarily through the hypothalamus. Shivering is the most potent mechanism for increasing heat production.

Both are true Normally, body temperature is maintained by a neural-feedback system controlled by hypothalamic temperature-regulating centers. The anterior hypothalamic preoptic area contains temperature sensing neurons. The hypothalamus integrates thermal information from most body tissues and maintains normal core temperature by several mechanisms. In response to cold, heat production is increased through shivering and nonshivering thermogenesis, and heat loss is decreased through vasoconstriction induced by posterior hypothalmic sympathetic centers. In response to heat, environmental heat loss is increased through sweating. *** Shivering is the most potent mechanism for increasing heat production. The human body has the remarkable capacity for maintaining its core temperature somewhere between 98°F and 100°F regardless of ambient temperatures on a range between 68°F and 130°F.

All cells, including neurons, have a resting membrane potential that is typically around (-)70 mV. An action potential is propagated with the same shape and size along the entire length of the axon.

Both are true 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: Leakage of potassium and sodium through nerve membranes. There are channel proteins in the nerve membrane through which potassium and sodium ions can leak, called a potassium-sodium "leak" channel. The emphasis is on potassium because, on average, the channels are far more permeable to potassium than to sodium, normally about 100 times as permeable. This differential in permeability is exceedingly important in determining the level of the normal resting membrane potential. The sodium/potassium pump establishes the sodium and potassium gradients across the membrane using ATP. Important: This pump is an electrogenic pump because more positive charges are pumped to the outside than to the inside (three Na+ ions to the outside for each two K+ ions to the inside), leaving a net deficit of positive ions on the inside; this causes a negative potential inside the cell membrane. Remember: The action potential is propagated rather than merely being conducted; it is regenerated as it moves along the axon. In this way an action potential remains the same size and shape as it is conducted. Visceral smooth muscle and cardiac pacemaker cells lack a stable resting membrane potential.

Motor signals are transmitted directly from the cortex to the spinal cord through the corticospinal tract and indirectly through multiple accessory pathways that involve the basal ganglia, cerebellum and various nuclei of the brain stem. The most important output pathway from the motor cortex is the corticospinal tract, also called the pyramidal tract.[refer to AS card 195-I for illustration]

Both are true The corticospinal tract (aka, pyramidal tract) is a group of fibers that carries messages for voluntary motor movement (fine skilled movements of skeletal muscle) to the lower motor neurons in the brain stem and spinal cord. The corticospinal tract originates about 30% from the primary motor cortex, 30% from the premotor and supplementary motor areas and 40% from the somatosensory areas posterior to the central sulcus. 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. background image Descending pathways can be subdivided into (1) a lateral system, which ends on motor neurons to limb muscles and on the lateral group of interneurons, and (2) a medial system, which ends on the medial group of interneurons. The lateral system includes the lateral corticospinal tract and part of the corticobulbar tract. These pathways influence the contralateral motor neurons that supply the musculature of the limbs, especially the digits and the muscles of the lower part of the face and the tongue. The medial system includes the ventral corticospinal, lateral and medial vestibulospinal, reticulospinal and tectospinal tracts. These pathways mainly affect posture and provide the motor background for movement of the limbs and digits.

The most important feature of the hemoglobin molecule is its ability to combine loosely and reversibly with oxygen Oxygen does not combine with the two positive bonds of the iron in the hemoglobin molecule. Instead it binds loosely with one of the so called coordination bonds of the iron atom

Both are true The primary function of hemoglobin in the body is to combine with oxygen in the lungs and then to release the oxygen readily in the peripheral tissue capillaries. Hemoglobin is the oxygen bearing protein of red blood cells and exists in two conformational states: Tense and relaxed The T confirmation has a weaker affinity for oxygen while the R confirmation has a stronger affinity for oxygen As oxygen binds to one monomer of hemoglobin, the tetramer's conformation shifts from the T (tense) state to the R (relaxed) state. This shift promotes the binding of oxygen to the remaining three monomer's heme groups, thus saturating the hemoglobin molecule with oxygen.[

The organic matrix of enamel is made from noncollagenous proteins only and contains several enamel proteins and enzymes. Of the enamel proteins, 90% are a heterogenous group of low-molecular-weight proteins known as amelogenins.

Both are true The remaining 10% consists of nonamelogenins such as enamelin and ameloblastin. Amelogenins: are hydrophobic proteins rich in proline, histidine and glutamine. Represent the main protein present in forming enamel; expression stops when enamel reaches full thickness. Loss of function: A thin hypoplastic enamel layer is formed that lacks enamel rods. Ameloblastin: this protein is present in much smaller amounts compared with amelogenin; it is found mostly in newly formed (secretory stage) enamel and more so at the outer surface than in deeper areas closest to the DEJ. Loss of function: terminal differentiating ameloblasts detach from the dentin and enamel formation aborts. Enamelin: this protein is the largest and the least abundant of the enamel matrix proteins; is present only at the growing enamel surface. Loss of function: not known. 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.

Glycogenolysis

Breakdown of glycogen into glucose in the liver and muscles

Aldehyde

CHO

Cardiac function is the volume of blood pumped each minute, and is expressed by which equation?

CO = SV x HR 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 to 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 (increased preload increases stroke volume). The contractility is the force that the muscle can create at the given length - increased contractility increases stroke volume. Afterload is the arterial pressure against which the muscle will contract (increased afterload decreases stroke volume). 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.

The entry of which of the following into the presynaptic terminal triggers the release of neurotransmitter?

Calcium 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, causing a change to the cell membrane's ion permeability and subsequent membrane potential. 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. Both electrical and chemical synapses are important means of cellular communication in the nervous system. Electrical synapses directly connect the cytosol of two neurons and allow rapid bidirectional current flow between neurons. They act as low-pass filters. Standard chemical synaptic transmission involves the release of transmitter from a presynaptic terminal, diffusion of transmitter across a synaptic cleft and binding of the transmitter to receptors on the opposed postsynaptic membrane. Note: The entry of calcium into the presynaptic terminal triggers the release of neurotransmitter. Note: Gap junctions are the morphological correlate of electrical synapses. Gap junctions contain channels formed by hemichannels called connexons. Connexons are formed by proteins called connexins

Which of the following serves as a principal source of carbon for nonessential amino acids?

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 the hydroxylation of the essential amino acid phenylalanine. Remember: The essential amino acids include: valine, threonine, leucine, methionine, isoleucine, lysine, phenylalanine, histidine and tryptophan. The nonessential amino acids include: alanine, asparagine, cysteine, glutamine, proline, tyrosine, arginine, aspartate, glutamate, glycine and serine. Note: Although cysteine's carbon skeleton can be formed from carbohydrates, cysteine requires the essential amino acid methionine to supply the sulfhydryl group. Important: Nonessential amino acids can be synthesized from the corresponding α-keto acids, an α-amino acid (as the NH3+ donor), a specific transaminase enzyme and pyridoxal phosphate ([PLP], the coenzyme form of vitamin B6). These amino acids include alanine, aspartate and glutamate. The other nonessential amino acids are synthesized by amidation (glutamine and asparagine). Amino acids are degraded to carbon dioxide, water and urea. The separation of the amino nitrogen from the carbon skeleton is an early event in the catabolism of most amino acids. In most cases, the amino group is initially transferred to α-ketoglutarate in a transamination reaction. The glutamate formed in these reactions is oxidatively deaminated by glutamate dehydrogenase, forming free ammonia. Note: Because ammonia is toxic, it has to be converted to nontoxic urea in the urea cycle. This pathway is present only in the liver. Note: The carbon skeletons of the amino acids are channeled either into gluconeogenesis (glucogenic amino acids) or into ketogenesis (ketogenic amino acids).

In which of the following structures are Chondroitin sulfates chiefly locate?

Cartilage Aorta Cell membranes

Vitamin B12 is also known as

Cobalamin

Pantothenic acid is a component of:?

Coenzyme A Pantothenic acid, also called vitamin B5 is a water-soluble B vitamin and therefore an essential nutrient. All animals require pantothenic acid in order to synthesize coenzyme A (CoA) - essential for fatty acid metabolism - as well as to in general synthesize and metabolize proteins, carbohydrates, and fats.

Saltatory conduction happens in myelinated neurons only. Which of the following are effects of saltatory conduction compared to conventional conduction?Select all that apply.

Conduction is faster and 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: Increases velocity of nerve transmission in myelinated fibers. 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: Diameter of the nerve fiber - the larger the diameter, the faster the conduction velocity because an increase in diameter reduces resistance to current flow down the axon. Presence of myelin sheath - which of course, increases conduction velocity.

What two reactions require Vitamin B12

Conversion of Methylmalonic Acid to Succinyl CoA which is important for fatty acid synthesis., Transfer of methyl group from THF. B12-methyl then transfers to homocysteine which turns into methionine.

Which of the following is a part of active cytochrome oxidase?

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 Lysyl oxidase is an extracellular copper-dependent enzyme that catalyzes formation of aldehydes from lysine residues in collagen and elastin precursors.[14][15] These aldehydes are highly reactive, and undergo spontaneous chemical reactions with other lysyl oxidase-derived aldehyde residues, or with unmodified lysine residues. This results in cross-linking collagen and elastin, which is essential for stabilization of collagen fibrils and for the integrity and elasticity of mature elastin. The importance of lysyl oxidase-derived cross-linking was established from animal studies in which lysyl oxidase was inhibited either by nutritional copper-deficiency or by supplementation of diets with β-aminopropionitrile (BAPN), an inhibitor of lysyl oxidase.[17] This resulted in lathyrism, characterized by poor bone formation and strength, hyperextensible skin, weak ligaments, and increased occurrence of aortic aneurysms. These abnormalities correlated well with decreased cross-linking of collagen and elastin. Developmentally, reduced lysyl oxidase levels have been implicated in Menkes disease

Which of the following is the metabolic pathway in which there is a shuttling of glucose and lactate between muscle and liver during exercise?

Cori 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. The lactate is taken up by the liver and converted to glucose, which is released back into the circulation The cycle's importance is based on the prevention of lactic acidosis in the muscles under anaerobic conditions

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 that controls skilled voluntary movement is the: [refer to AS card 195-I for illustration]

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.

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. Craig has a higher than normal heart rate (tachycardia). Gary's ventricles contract nearly simultaneously with the atria. Ashley's right ventricle does not contract on the lateral side. Jimmy's entire left ventricle does not contract. [refer to AS card 160-I for illustration]

Craig- Sinoatrial node (the pacemaker of the heart) Gary- Atrioventricular node (the portion responsible for delaying impulses as they pass from the atria to the ventricles) Ashley- Purkinje fibers (they are not transmitting impulses to the lateral side of the right ventricle) Jimmy- Atrioventricular bundle (the AV bundle is divided, and the left bundle is not transmitting impulses). Note: 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 superior lateral 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 in the posterior wall of the right atrium behind the tricuspid valve within the lower right interatrial septum. An impulse is delayed in the AV node for about 0.13 seconds to allow the atrial blood to empty into the ventricles before ventricular contraction occurs. Aside from the AV node, the atria and ventricles are electrically isolated. AV bundle (bundle of His): originates in the AV node, passes subendocardially down the right side of the interventricular septum for about 1 cm and then divides into the right and left bundle branches. Purkinje fibers: originate from the right and left bundle branches, extending to the papillary muscles and lateral walls of the ventricles. The wave of depolarization travels extremely fast through the bundle branches and Purkinje fibers (total elapsed time of 0.03 seconds).

All of the following are the most useful enzymes for the diagnosis of acute myocardial infarction

Creatine kinase Lactate dehydrogenase Alanine transaminase In the diagnosis of acute myocardial infarction, enzyme determinations can provide only estimates of the extent of the damage, whereas an ECG can locate the site of the infarction. However, an ECG does not distinguish between old defects and a recent infarction, whereas enzyme elevations are diagnostic for recent and ongoing tissue damage. *** Creatine kinase (specifically CK-2 along with CK-3) is the first heart enzyme to appear in the blood after a heart attack, followed by AST 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. In the heart: Creatine kinase (CK): CK-2 along with CK-3 Lactate dehydrogenase (LDH): specifically H subunits Aspartate transaminase (AST) background image Levels of lipase and amylase are elevated in acute pancreatitis and their main use is the differential diagnosis in patients who present with severe abdominal pain of sudden onset. CK is used for the diagnosis of muscle diseases. Along with LDH, AST and myoglobin levels, CK level is elevated in dermatomyositis, polymyositis and muscular dystrophies. Elevated LDH with more or less normal AST and CK levels is typical for pulmonary infarction. Glutamyl transferase (GGT) is used as a sensitive indicator of biliary obstruction. Acid phosphatase (ACP) and prostate-specific antigen (PSA) are tumor markers used for the diagnosis and follow-up of patients with prostatic cancer. Previous Flip Card Next

Genetic recombination experiments depend heavily upon the actions of which enzymes?

DNA ligases And restriction endonucleases

To bring his blood pressure down to normal, he could attempt to do what to the total peripheral resistance?

Decrease it

All of the following factors and conditions that decrease insulin secretion

Decreased blood glucose Fasting Somatostatin Alpha adrenergic activity Insulin lowers blood sugar by binding to tyrosine kinase receptors on strained muscle and adipose membranes resulting in a cascade that trans located GLUT-4. Glut 4 transporters allow facilitated diffusion of glucose into the muscle and fat cells

Niacin: Vitamin B3 characteristics

Deficiency in Niacin causes Pellegra, a disease which is caused by a lack of the vitamin niacin (vitamin B3).[2] Symptoms include inflamed skin, diarrhea, dementia, and sores in the mouth.[1] Areas of the skin exposed to either sunlight or friction are typically affected first.[1] Over time affected skin may become darker, stiffen, peel, or bleed.[1][3] Niacin also serves as a precursor for NAD and NADP and is involved in DNA repair Niacin is part of the metabolizing process of forming serotonin from tryptophan. Therefore, niacin deficiency can directly impact mood by affecting your production of serotonin. Foods with niacin: yeast, liver, meats, peanuts, cereals, and legumes

All of the following statements concerning transamination reactions are true

Description DescriptionTransamination, a chemical reaction that transfers an amino group to a ketoacid to form new amino acids. This pathway is responsible for the deamination of most amino acids. This is one of the major degradation pathways which convert essential amino acids to non-essential amino acids transaminases (aminotransferases) catalyze the transfer of amino groups; all transaminases require the coenzyme pyridoxal phosphate. 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 α-keto acid.

When arterioles are acted on by nitric oxide or adenosine, they will:

Dialate Important: Arterioles are the primary resistance vessels and determine the distribution of cardiac output. Arteriolar resistance is regulated by the autonomic nervous system. Remember: Alpha1-adrenergic receptors are found on the arterioles of the skin and splanchnic circulations. Beta2-adrenergic receptors are found on arterioles of skeletal muscle. Beta1-adrenergic receptors are found primarily in the heart muscle and kidneys. Beta blockers are commonly prescribed for their antihypertensive effects. 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. Previous Flip Card Next

Which of the following is the best known stimulus for increasing the rate of thyroid stimulating hormone (TSH) secretion by the anterior pituitary gland?

Exposure to cold Thyroid stimulating hormone secretion is stimulated by the thyroid releasing hormone.

Riboflavin is a precursor of:?

FMN and FAD Riboflavin is also known as Vitamin B2 It's only biological function is as a precursor of flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN) Riboflavin deficiency is most common in alcoholics

Your patient has a defective mitral valve, allowing backflow. Which of the following cardiac phases will be least affected by this defect?

Filling phase

Which process occurs in Bowman's capsule?

Filtration

. Which two of the following processes in the formation of urine involve the most similar amounts of fluid transport?

Filtration and reabsorption filtration and reabsorption - about 99% of the filtrate is reabsorbed

Which two processes supplement each other, working in the same "direction"?

Filtration and secretion filtration and tubular secretion - both send substances from blood to tubules

Which of the following pituitary hormones regulate Serotoli cells of the seminiferous tubules of the testes?

Follicle simulating hormone Sertoli cells are activated by the follicle simulating hormone. FSH is essential for the initiation of spermatogenesis

Growth and preparation of the chromosomes for replication occurs in which phase of the cell cycle?

G1 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 G0 (G zero). Many G0 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)

In a cotton candy eating competition you consume 14 moderately sized and overpriced bags of threaded sugar. This caused your portal vein to drop tremendous loads of glucose to your hepatocytes soon after. Which of the following enzymes functions only when this happens?

Glucokinase

Gluconeogenesis

Glucose synthesis from non carbohydrate sources

sources of ammonia

Glutamine Amine Amino acids

Which compound is converted to ammonia mainly in the kidney?

Glutamine 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.

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 are:

Glycogen Cellular respiration Creatine phosphate: the phosphate group in creatine phosphate is attached by a "high energy" bond like that in ATP. Creatine phosphate derives it's high-energy phosphate from ATP and can donate the phosphate back to ADP to form ATP.

Glycogen synthesis for glucose

Glycogenesis

Glycosaminoglycans

Glycosaminoglycans[1] (GAGs) or mucopolysaccharides[2] are long linear polysaccharides consisting of repeating disaccharide (double sugar) units. Except for keratan, the repeating unit consists of an amino sugar, along with a uronic sugar or galactose.[3] Because GAGs are highly polar and attract water, they are used in the body as a lubricant or shock absorber. Mucopolysaccharidoses are a group of metabolic disorders in which abnormal accumulations of glycosaminoglycans occur because of enzyme deficiencies.

BPG (2,3-bisphosphoglycerate)

Greatly reduces hemoglobin's affinity for O2 by binding allosterically. Stabilizes T-state. Transfer of O2 can improve because increased delivery in tissues can outweigh decreased binding in the lungs. When 2,3-BPG binds to deoxyhemoglobin, it acts to stabilize the low oxygen affinity state (T state) of the oxygen carrier. Infants have a low affinity for 2,3 BPG resulting in a higher binding affinity for oxygen.

The major regulatory enzyme of cholesterol synthesis is:

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 absorption depends upon the presence of bile salts in the intestinal lumen

Which of the following enzymes are involved in unwinding, unzipping, and rezipping the DNA molecule during replication?

Helicases unwind the DNA Topioisomerases are responsible for unwinding supercoiled DNA DNA hyraxes reforms the supercoiled structure once the replication fork has passed

Mean Corpuscular Volume (MCV)

Hematocrit/ red blood cell count

The most common form of adult hemoglobin in the adult human being is:?

Hemoglobin A Hemoglobin H is an abnormal hemoglobin composed of four beta chains, it is usually associated with a defect in three of the four alpha chains resulting in alpha-thalassemia (a blood disorder that reduces how well the body produces healthy red blood cells and normal hemoglobin. Hemoglobin S is an abnormal hemoglobin in which valine has replaced b 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 (e.g. exercise) Hemoglobin M: is a group of abnormal hemoglobin in which a single amino acid substitution favors the formation of methemoglobin and is thus associated with methemoglobinemia Hemeglobin C is an abnormal hemoglobin in which lysine has replaced glutamic acid, causing reduced plasticity of the red blood cells

Mean Corpuscular Hemoglobin Concentration (MCHC)

Hemoglobin/ hematocrit

The general term for reactions that prevent or minimize loss of blood from the vessels if they are injured or ruptured is:?

Hemostasis 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 which leads to clotting. The process stops bleeding without stopping blood flow through the injured vessel

Which of the following is the first step to use energy rather than produce it?

Hexokinase

Your patient presents with stage 2 hypertension. His blood pressure is 150 mmHg/99 mmHg, confirming his diagnosis. 1. Is his pulse pressure normal, high, or low?

High

Which of the following glycosaminoglycans can be found functioning in synovial fluid?

Hyaluronic acid

GnRH (gonadotropin-releasing hormone) is produced by the:

Hypothalamus

A patient of yours suffers from phenylketonuria (PKU). Your dental assistant offers her a bottle of soda. The patient, a dental student, responds by saying: Which supplement would you expect this patient to be taking?

I cannot have this because it contains phenylalanine, which I am unable to metabolize Tyrosine 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.

Which class of antibody is the first antibody to appear in the circulation after antigen stimulation?

IgM

Venous return (VR) is the flow of blood back to the heart. Under steady-state conditions, venous return must equal _______ when averaged over time because the cardiovascular system is essentially a closed loop.

In ventricular contraction, preload is stretch of the fibers by blood during ventricular filling. Afterload is the arterial pressure against which the ventricle ejects the blood. An increase in myocardial fiber length, as occurs with augmented ventricular filling (preload) during diastole, produces a more forceful ventricular contraction. This relationship between fiber length and strength of contraction is known as the Frank-Starling relationship or Starling's law of the heart. Preload value is related to right atrial pressure. The most important determining factor for preload is venous return. Afterload for the left ventricle is determined by aortic pressure; afterload for the right ventricle is determined by pulmonary artery pressure. Contractility is an expression of cardiac performance at a given preload and afterload. Contractility can be modulated by the autonomic nervous system. Increases in heart rate will also increase cardiac output, EXCEPT at very high heart rates where there will be less time for filling. Sympathetic activation of the heart will increase heart rate, conduction velocity in the heart and contractility of the cardiac muscle. The myocardium functions only aerobically and in general, it uses substrates in proportion to their arterial concentration.

Nucleoside

Includes a nitrogen base and a ribose or deoxyribose sugar A nucleotide however also contains a phosphate

Which of the following structures of the eye functions like a shutter in the camera analogy, allowing more or less light into the eye?

Iris The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. The cornea, with the anterior chamber and lens, refracts light, with the cornea accounting for approximately two-thirds of the eye's total optical power.

polysynaptic reflex

Is a complex reflex in which one or more interneurons are interposed between afferent and efferent neurons. A polysynaptic reflex arc may have hundreds of synapses

Etner-Doudoroff Pathway

Is an alternative to glycolysis and is used by many obligate aerobic bacteria and results in the net production of 1 ATP molecule per glucose metabolized These bacteria lack 6-phosphofructokinase or aldolase

Hemochromatosis

Is an iron storage disease that results in the deposition of iron containing pigments in the peripheral tissues and is characterized by the bronzing of skin, diabetes and weakness

Embden-Meyerhof pathway

Is another name for glycolysis by which glucose is converted to pyruvate. Glycolysis occurs in the cytosol of all living cells and does not require oxygen This is the most common pathway and is used by a large number of anaerobic and facultatively anaerobic bacteria Oral bacteria use this pathway This glycolytic pathway results in the net production of 2 ATP molecules per glucose metabolizes

The isoelectric point

Is the pH at which the number of positive and negative charges on a molecule equal each other The isoelectric point (pI, pH(I), IEP), is the pH at which a molecule carries no net electrical charge or is electrically neutral in the statistical mean. The standard nomenclature to represent the isoelectric point is pH(I).[1] However, pI is also used.[2] For brevity, this article uses pI. The net charge on the molecule is affected by pH of its surrounding environment and can become more positively or negatively charged due to the gain or loss, respectively, of protons (H+).

All amino acids found in proteins are of the:

L configuration 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 cell (plasma) membrane is a fluid mosaic of:

Lipids and proteins The cell membrane is composed mainly of lipids and proteins. The lipids form a bilayer with peripheral and integral proteins spanning the membrane The membrane is said to be a fluid mosaic since lipids and proteins can diffuse laterally within the plane of the membrane

Most plasma proteins are derived from the:

Liver Most plasma proteins are derived from the liver. In all, the liver synthesizes about 25 g of plasma proteins every day, which accounts for nearly 50% of the total protein synthesis in the liver. Only the immunoglobulins are not produced by the liver. They are synthesized by plasma cells. Most plasma proteins (exception: albumin) are glycoproteins. They circulate for several days and are eventually removed from the circulation when their oligosaccharide chains are worn down.

The misinformed structures of the hindbrain consists of:?

Medulla oblongata Pons Cerebellum

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.

Medulla/concentration/hyperosmotic/elevated The renal medulla is the interior portion of the kidney where the primary functions of the organ occur: the filtering of waste materials and elimination of fluid from the body. The kidney filters blood and sends waste materials to the bladder to become excreted urine. The counter current multiplier or the counter current mechanism is used to concentrate urine in the kidneys by the nephrons of the human excretory system. The nephrons involved in the formation of concentrated urine extend all the way from the cortex of the kidney to the medulla and are accompanied by vasa recta.

Which valve is unique in having a different number of cusps than the others? [refer to AS card 167-I, 167 B-I for illustration]

Mitrial 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 during systole 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. The first heart sound (S1) corresponds to closure of the AV valves; the second heart sound (S2) corresponds to closure of the semilunar valves.

The liver releases glucose back into the circulating blood during exercise. Which organs take to this extra glucose?

Muscle Brain Glucose is the only fuel source for red blood cells, cornea, lens because these cells have no mitochondria Kidney, medulla, testes, leukocytes, white muscle fibers use a lot of glucose because these cells have very few mitochondria

Muscle spondlesy

Muscle spindles are stretch receptors within the body of a muscle that primarily detect changes in the length of the muscle. They convey length information to the central nervous system via afferent nerve fibers. This information can be processed by the brain as proprioception. The finer the movement required, the greater the number of muscle spindles in a muscle Tone of muscle is regulated by the muscle spindles which measure length and the golgi tendon organ which is innervated by a single group In sensory afferent fibers golgi tendon organ is a proprioceptor, sense organ that receives information from the tendon, that senses TENSION. When you lift weights, the golgi tendon organ is the sense organ that tells you how much tension the muscle is exerting.

Plasma osmolarity

Osmolarity is affected by changes in water content, as well as temperature and pressure. Drinking can also inhibit vasopressin secretion, even before it produces a detectable decrease in plasma osmolarity or sodium. This effect does not depend on the water reaching the stomach, and is unrelated to changes in blood pressure or blood volume.

Which of the following is an etiology off conductive hearing loss?

Otitis media: An infection of the air-filled space behind the eardrum (the middle ear). An ear infection is usually caused by bacteria or viruses. Otosclerosis: An inherited disorder that causes hearing loss due to the ear's inability to amplify sound. There are three small bones that connect to the ear drum to help amplify sound waves. When someone has this condition, one of the bones is unable to vibrate freely. Impacted cerumen: Impacted cerumen (se-ROO-men) is when earwax (cerumen) builds up in the ear and blocks the ear canal; it can cause temporary hearing loss and ear pain.

Use the same answer options for the following questions. The ventricles are completely depolarized during which isoelectric portion of the ECG? This portion of the ECG represents atrial depolarization. This portion of the ECG represents the segment between depolarization of the atria and depolarization of the ventricl

P wave: represents atrial depolarization prior to the atria's contraction T wave: represents ventricular repolarization QRS complex: represents ventricular depolarization 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 ventricular 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.

Parasympathetic fibers innervate the heart by way of the vagus nerves.

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. background image The SA node serves as the cardiac pacemaker to initiate the cardiac impulse. This impulse is propagated from the SA node to the atria and ultimately reaches the AV node. After a delay in the AV node, the cardiac impulse is propagated throughout the ventricles. Velocity of conduction: highest in Purkinje system; slowest in AV node. The properties of automaticity (the ability to initiate its own beat) and rhythmicity (the regularity of pacemaker activity) allow a perfused heart to beat even when it is completely removed from the body. Automaticity: greater in SA node than in AV node which is greater than in Purkinje system.

The principal hormone for serum calcium regulation is:?

Parathyroid hormone Calcium levels are regulated primarily by the parathyroid hormone and also by vitamin D and calcitonin. Parathyroid hormone and vitamin D increase serum calcium, while calcitonin decreases blood calcium levels Patients with hyperparathyroidism will have decreased renal calcium excretion and will also be predisposed to an increased likelihood of bone fracture because PTH's primary purpose is to increase the concentration of serum calcium.

The activity level of which enzyme controls the rate of glycolysis? - 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.This allosteric enzyme is up-regulated by ADP and AMP and is inhibited by ATP, H+ 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).

Which of the following enzymes is responsible for dissolving blood clots?

Plasmin Plasmin (aka fibrinolysin) 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 dissolution of 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. Deficiency in plasmin can lead to thrombosis and defective wound healing.

The major intracellular cation is:

Potassium Functionally, the body's water is effectively compartmentalized into two major fluid compartments: 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: Interstitial fluid (ISF) surrounds the cells, but does not circulate. It comprises about ¾ of the ECF. Plasma circulates as the extracellular component of blood. Plasma makes up about ¼ of the ECF. 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, mucous, e

Leukotrienes

Potent bronchoconstrictors and cause airway wall edema, increasing mucus production. They also attract eosinophils into the tissues and amplify the inflammatory process

The famous relationship stated in the Henderson Hasselbach equation can be used to:

Predict the pH that acid buffers work best at

The ground substance of the extracellular matrix is made of:?

Proteoglycan molecules Proteoglycans consists of a core protein with glycosaminoglycans attached in a brush like fashion and are 95% polysaccharide and 5% protein Major functions include: lubricants, extracellular matrix, and being a molecular sieve

Which of the following cells in the body metabolize glucose only through anaerobic pathways

Red blood cells Though they are never really in an oxygen deprived environment, they do not have mitochondria and therefore cannot send pyruvate to the citric acid cycle

Sugars that contain aldehyde groups that are oxidized to carboxylic acids are classified as: - Nonreducing sugars - Reducing sugars - Polar sugars - Nonpolar sugars

Reducing sugars Benedict's test: Aldehyde + Benedict's reagent ——-> carboxylate + brick red precipitate (Cu2O),(s)

A zymogen is converted to its active enzyme form by which of the following mechanisms?

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, so as to regulate when and where the enzyme becomes activated. Note: The release and activation of the pancreatic zymogens is mediated by the secretion of cholecystokinin, secretin and the parasympathetic nervous system.

As the acidic stomach contents pass into the small intestine, the low pH triggers secreting of the hormone _______ into the blood.

Secretin

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 Those cells in the anterior (ventral) horn transmit motor impulses

Molecules that can easily penetrate a biological membrane are usually

Small and nonpolar The most important property of the lipid bilayer is that it is a highly impermeable structure. Only water and gases such as oxygen and carbon dioxide can easily pass through the bilayer This means that large and small polar molecules cannot cross without the assistance of other structures

The effectors of the autonomic nervous system include:?

Smooth muscle Glands Cardiac muscle The autonomic nervous system (ANS) is a motor system that controls smooth muscle, cardiac muscle and glands. It helps maintain homeostasis and coordinates responses to external stimuli. Its components are the sympathetic, parasympathetic and enteric nervous systems. Autonomic motor pathways have preganglionic and postganglionic neurons. Preganglionic neurons reside in the CNS, whereas postganglionic neurons lie in peripheral ganglia.

The thick ascending limb of the loop of Henle is called the "diluting segment" because

Sodium chloride (NaCl) is reabsorbed without water

The primary action of local anesthetics in producing a conduction block is to decrease the permeability of the ion channels to:

Sodium ions Local anesthetics selectively inhibit the peak permeability of sodium, whose value is normally about five to six times greater than the minimum necessary for impulse conduction. The following sequence is a proposed mechanism of action of local anesthetics: Displacement of calcium ions from the sodium channel receptor site, which permits... Binding of local anesthetic molecule to this receptor site, which thus produces... Blockade of the sodium channel, and a... Decrease in sodium conductance, which leads to... Depression of the rate of electrical depolarization, and a... Failure to achieve the threshold potential level, along with a... Lack of development of propagated action potentials, which is called... Conduction blockade The mechanism whereby sodium ions gain entry to the axoplasm of the nerve, thereby initiating an action potential, is altered by local anesthetics. The nerve membrane remains in a polarized state because ionic movements responsible for the action potential fail to develop. Nerve block produced by local anesthetics is called a nondepolarizing nerve block. background image Local anesthetics reversibly block nerve impulse conduction and produce reversible loss of sensation at their administration site. The site of action of local anesthetics is at the lipoprotein sheath of the nerves. Local anesthetics are clinically effective on both axons and free nerve endings. Important: Small, myelinated nerve fibers which conduct pain and temperature sensations are affected first, followed by touch, proprioception, and skeletal muscle tone. Emergence from a local anesthetic nerve block follows the same diffusion patterns as induction does; however, it does so in reverse order. Recovery is usually a slower process than induction because the anesthetic is bound to the drug receptor site in the sodium channel and therefore is released more slowly than it is absorbed. Potassium, calcium, and chloride conductance's remain unchanged.

Your patient has just finished her 2-hour appointment and is eager to get out of 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 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, 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, alters 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.

Which intestinal enzyme breaks down the O-glycosidic bond between glucose and fructose?

Sucrase

The most common pathway of glycolysis is:?

The Embden-Meyerhof pathway

Glycolysis

The breakdown of glucose to two molecules of pyruvic acid

Caries activity is directly proportional to?

The consistency of fermentable carbohydrates ingested The frequency of ingesting fermentable carbohydrates The oral retention of fermentable carbohydrates ingested 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 byproduct. 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.

Characteristics of saliva

The important properties of saliva are a large flow rate relative to the mass of gland, low osmolarity, high K+ concentration and organic constituents - including enzymes (amylase, lipase), mucin and growth factors. The inorganic composition is entirely dependent on the stimulus and the rate of salivary flow, which is stimulated during a meal. The major components are Na+, K+, HCO3-, Ca2+, Mg2+ and Cl-. Note: In humans, salivary secretion is always hypotonic due to the fact that the salivary ductal cells reabsorb sodium and chloride in exchange for potassium and bicarbonate. The organic constituents of saliva, proteins and glycoproteins, are synthesized, stored and secreted by the acinar cells. The major products are amylase (an enzyme that initiates starch digestion), lipase (important for lipid digestion), glycoprotein (mucin, which forms mucus when hydrated) and lysozyme (attacks bacterial cell walls to limit colonization of bacteria in the mouth). Note: Saliva supplies calcium and phosphate, which are important for remineralization 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.

Which is true about protein structure?

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. The two cysteine residues that react to form the disulfide bond (a covalent 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. Many proteins are composed of two or more polypeptide chains, generally referred to as subunits, which associate through noncovalent interactions and occasionally, disulfide bonds to form protein quaternary structures. It has been known for long that the functions of proteins are closely related to their quaternary structure.

Glycogen is primarily found in

The liver and skeletal muscles

Nephron

The nephron is the basic structural and functional unit of the kidney. The nephron's chief function is to regulate the concentration of water and soluble substances like sodium salts by filtering the blood, reabsorbing what is needed and excreting the rest as urine. Two general classes of nephrons are cortical nephrons and juxtamedullary nephrons. Cortical nephrons have their renal corpuscle in the superficial renal cortex, while the renal corpuscles 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.

Your patient just returned from an ophthalmology appointment where she received TROPICAMINDE to induce MYDRIASIS. What significance does this have on her dental appointment?

The patient will be extra sensitive to the overhead dental light MYDRIASIS is prolonged abnormal dialation of the pupil of the eye induced by a drug or caused by a disease and causes the eyes to become extra sensitive to light

Hematocrit

The percent of the volume of whole blood that is composed of red blood cells as determined by separation of red blood cells from the plasma usually by centrifugation.

Which of the following statements concerning the two principal laws of thermodynamics is true?

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: Heat flows spontaneously from a hot body to a cool one One cannot convert heat completely into useful work 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 (DG) is negative. Chemical reactions in which the products have more free energy than the reactants are endergonic. For these reactions, the ΔG is positive, and heat is consumed as a reactant. Previous

Which of the following are the same in RNA and DNA molecules?

The purines A and G are the same however the pyrimidine bases are different

Krebs Cycle (Citric Acid Cycle) characteristics

The pyruvate that enters this cycle is generated by the glycolysis of glucose or protein catabolism The cycle starts with the 4-carbon compound oxaloacetate, adds 2 carbons from Avery-CoA, loses 2 carbons as CO2 and regenerates the 4-carbon compound oxaloacetate This cycle is controlled by the regulation of several enzyme activities. The most important of these regulated enzymes are citrate synthase, isocitrate dehydrogenase and alpha ketoglutarate dehydrogenase complex The enzymes involved in the citric acid cycle are found in the mitochondria

Prostaglandins characteristics

They have a very short half life They generally act locally on or near the tissue that produced them 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 Prostaglandins are synthesized by a broad variety of tissues Prostaglandin belong to a subclass of lipids known as the eicosanoids Prostaglandins inhance inflammatory effects whereas aspirin diminishes them

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, especially cones, so images are focused on the fovea can be seen in greater detail

The determination of the prothrombin time is the most important laboratory test for the evaluation of the vitamin K status

True Prothrombin Prothrombin (coagulation factor II) is proteolytically cleaved to form thrombin in the clotting process. Thrombin in turn acts as a serine protease that converts soluble fibrinogen into insoluble strands of fibrin, as well as catalyzing many other coagulation-related reactions.

A large percentage of biotin requirement in humans is supplied by intestinal bacteria

True

Acetylcholine - in most instances, acetylcholine has an excitatory effect; however, it is known to have inhibitory effects at some peripheral parasympathetic nerve endings, such as inhibition of the heart by the vagus nerves

True

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.

True

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.

True

Carbonic anhydrases are zinc containing enzymes

True

Dna is hydrophilic mRNA is the most abundant

True

During the upstroke of the action potential, the cell depolarizes, or becomes less negative. The depolarization is caused by inward current (i.e., 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).

True

Edema tends to develop when plasma albumin concentration falls below 2g/dL

True

Enamel hypoplasia is a defect in the formation of the enamel matrix. Enamel hypoplasia is a general term referring to all quantitative defects of enamel thickness. They range from single or multiple pits to small furrows and wide troughs to entirely missing enamel. Note: Hypocalcification and opacities are qualitative defects. 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. 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.

True

Final electron is oxygen and it is reduced to water

True

For reasons still not understood, at the time of puberty, the secretion off hypothalamic GnRH breaks through the childhood inhibition and adult sexual life begins

True

Hematocrit refers to the volume percentage of red blood cells (erythrocytes) in blood. E.g. a hematocrit of 40 means that blood volume is composed of 40% erythrocytes and the remainder is plasma, leukocytes and thrombocytes. The average hematocrit value is about 42% in men and 38% in women. Generally, low values are indicative of anemia, while high values are observed in polycythemia. Hematocrit is measured by centrifugation of heparinized blood in a calibrated tube, which allows for a direct reading of the percentage of erythrocytes. An increase in hematocrit causes an increase in whole blood viscosity. At normal hematocrit, the viscosity of whole blood is about 3-4 cp (centipoise, or mPa·s), which signifies that three to four times as much pressure is required to push blood through a blood vessel as it would to push water. In polycythemia (hematocrit increases to 60 or 70), the viscosity of blood is about 10 times the viscosity of water, and blood flow through blood vessels becomes sluggish. Note: Blood is viscous because of the large number of red cells suspended in plasma. Each of these cells exerts frictional pull against the blood vessel wall and against adjacent cells. Other minor factors affecting the viscosity of blood are plasma protein content and types of plasma proteins. The viscosity of plasma is about 1.5 that of water.

True

In bacteria ribosomes are either free floating in the cytoplasm or attached to the plasma membrane and in eukaryotes they are either free floating in the cytoplasm or bound to the membrane of the endoplasmic reticulum

True

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 α-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).

True

Metabolic acidosis is caused either by an overproduction of organic acids or by an inability of the kidneys to excrete excess acid

True

Oxytocin is secreted by the posterior portion of the pituitary (neurohypophysis) in response to dialation of the cervix and to suckling

True

Phosphodiester bonds hold together the same strain Complementary strands are held together by hydrogen bone

True

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 be absorbed by enterocyytes.

True

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 unmyelinated nerve fibers. All axons of the PNS have a sheath of Schwann cells (and thus a neurilemma, made up of the outer layer of Schwann cells) around them. When a Schwann cell is wrapped successively around an axon, it becomes a myelin sheath. In the CNS, the sheath cells are called oligodendrocytes. 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.

True

Thin filaments are composed of actin

True

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 relationship, 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 decreases venous return.

True

Vitamin B12 binds tightly to INTRINSIC FACTOR and in this form, it is absorbed from the ileum. In the blood it binds tightly to TRANSCOBALAMIN II and other plasma proteins. This cobalamin-transcobalamin II complex is taken up into the cells by receptor mediated endocytosis. TRANSCOBALAMIN II directs the vitamin to the tissues in which it is needed and prevents renal excretion.

True

When a muscle is stretched, the stretch reflex reacts. This reflex is considered monosynaptic, and the result is contraction.

True

High levels of Creatine kinase and lactate dehydrogenase and aspartate amino transferase indicate Myocardial Infraction

True Aspartate aminotranferase levels can also detect alcohol hepatitis and alanine aminotransferase is used to detect viral hepatitis

In a normal person, about 90% of all erythropoietin is formed on the kidneys and the remainder is formed mainly in the liver

True Erythropoietin is a glycoprotein that causes the production of red blood cells

GABA is believed to cause an inhibitory effect

True Inhibitory neurotransmitters encourage the hyperpolarization of the postsynaptic cell, making it less likely to generate an action potential. This hyperpolarized state is achieved either by increasing Cl- flow into the cell (GABAA receptors) or increasing K+ flow out of the cell (GABAB receptors).

anti-diuretic hormone and oxytocin are secreted by the posterior pituitary.

True Posterior pituitary: The back portion of the pituitary, a small gland in the head called the master gland. The posterior pituitary secretes the hormone oxytocin which increases uterine contractions and antidiuretic hormone (ADH) which increases reabsorption of water by the tubules of the kidney.

Sensory receptors can be classified in terms of the types of energy that they transduce or according to the sources of the input.

True Sensory receptors can be classified in terms of the type of energy that they transduce (e.g., photoreceptors transduce light, mechanoreceptors transduce displacement and force) or according to the source of the input (e.g., exteroreceptors signal external events, proprioceptors signal the position of the body part with respect to space or another body part). Sensory receptors include exteroreceptors, interoreceptors and proprioceptors. Stimuli are environmental events that excite sensory receptors. Responses are the effects of stimuli and sensory transduction is the process by which stimuli are detected. Note: Interoreceptors (aka, visceroreceptors) are associated with the viscera or organs and provide information about the internal environment. For example, mechanoreceptors detect distension of the gut and fullness of the bladder. 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.

In cardiac muscle, the action potential is caused by opening of two types of channels.

True The action potential in a ventricular muscle fiber, averages about 105 millivolts, which means that the intracellular potential rises from a very negative value, about -85 millivolts, between beats to a slightly positive value, about +20 millivolts, during each beat. After an initial spike, the membrane remains depolarized for about 0.2 second, exhibiting a plateau, followed at the end of the plateau by abrupt repolarization. Important point: The presence of the plateau in the action potential causes ventricular contraction to last as much as 15 times as long in cardiac muscle as in skeletal muscle. At least two major differences between the membrane properties of cardiac and skeletal muscle account for the prolonged action potential and the plateau in cardiac muscle: First, the action potential of skeletal muscle is caused almost entirely by sudden opening of large numbers of so-called fast sodium channels that allow a tremendous amount of sodium to enter the muscle fiber. These channels are called fast channels because they remain open only for a very short period of time and then abruptly close. At the end of this closure, repolarization occurs and the action potential is over within another thousandth of a second or so. In cardiac muscle, the action potential is caused by opening of two types of channels: (1) the same fast sodium channels as those in skeletal muscle and (2) an entirely different population of slow calcium channels, which are also called calcium-sodium channels. This second population of channels differs from the fast sodium channels in that they are slower to open and, even more important, remain open for several tenths of a second. Secondly, a major functional difference between cardiac muscle and skeletal muscle that helps account for both the prolonged action potential and its plateau is the fact that immediately after the onset of the action potential, the permeability of the cardiac muscle membrane for the potassium ions decreases about five-fold, an effect that does not occur in skeletal muscle. Important: The strength of cardiac muscle contraction is directly proportional to intracellular Ca2+ concentration. background image The refractory period of atrial muscle is much shorter than that for the ventricles (about 0.15 second for the atria compared with 0.25 to 0.30 second for the ventricles). Therefore, the rhythmical rate of contraction of the atria can be much faster than that of the ventricles. 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.

Glomerular filtration rate is the best overall index of kidney function.

True The glomerular filtration rate (GFR) is the rate at which the glomeruli filter blood, normally about 120 ml/minute. Clinically, the GFR is evaluated by measuring plasma [creatinine]. GFR depends on: Permeability of capillary walls Vascular pressure Filtration pressure Clearance

Lactic acid fermentation is a reaction which occurs in cells without mitochondria or in cells when oxygen is limited

True Reaction occurs in cells without mitochondria (RBC) or in cells when oxygen is limited (muscle cells during excercise). The entire purpose of this reaction is to convert the NADH produced in step 6 of glycolysis back to NAD+ so that glycolysis can continue This is simply a redox reaction in which pyruvate is reduced to lactate by the enzyme lactate dehydrogenase

One of the two nitrogen atoms in urea comes from ammonia via carbomoyl phosphate; and the other from aspartate

True The aspartate nitrogen is derived either from ammonia, through the glutamate dehydrogenase reaction followed by transamination with oxaloacetate, or directly from transamination reaction

In Vitamin A deficiency, columnar epithelia are transformed into heavily keratinized squamous epithelia in a process known as SQUAMOUS METAPLASIA The retinoids, (retinal and retinoic acid) are the active forms of Vitamin A. Retinal is the prosthetic group of the RHODOPSINS, the visual pigments of rods and cones. Retinoic acid is a gene regulator that acts through nuclea receptors similar to the steroid hormones

True. All are true

Which layer is innervated by the autonomic nervous system?

Tunica media

Which layer is thicker: tunica media or tunica adventitia?

Tunica media

What is the substrate for glycogen synthesis?

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 α-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. background image Glycogen synthase occurs in both phosphorylated and dephosphorylated forms. The active enzyme, glycogen synthase A, is the dephosphorylated and active form and is activated (dephosphorylated) by insulin. Glycogen synthase B, is the phosphorylated and inactivated form of the enzyme and is inactivated (phosphorylated) by epinephrine (in muscle and liver) and glucagon (in liver). 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 dephosphorylation forms the inactive enzyme (b). Glycogen phosphorylase is activated (phosphorylated) by glucagon and epinephrine and inactivated (dephosphorylated) by insulin. Important: Both enzymes (glycogen synthase and phosphorylase) are phosphorylated at specific serine residues.

O blood is referred to as:?

Universal donor Type O people do not produce AB antigens. Therefore, type O people's blood normally will not be rejected when it is given to others with different blood types Blood type AB is the universal recipient

Manifestations of the allergy induced histamine

Vasodilation particularly of small blood vessels Bronchoconstriction Increased capillary permeability Secretion of HCL

Pernicious anemia is caused by the malabsorption of:

Vitamin B12 Vitamin B12 deficiency anemia, of which pernicious anemia (PA) is a type,[8] is a disease in which not enough red blood cells are produced due to a deficiency of vitamin B12. Pernicious anemia refers to anemia that results from lack of intrinsic factor. Intrinsic factor (IF), also known as gastric intrinsic factor (GIF), is a glycoprotein produced by the parietal cells of the stomach. It is necessary for the absorption of vitamin B12 Lack of intrinsic factor is most commonly due to an autoimmune attack on the cells that create it in the stomach.

Which vitamin plays a role in amino acid metabolism?

Vitamin B6 Vitamin B6 is part of the vitamin B group of essential nutrients. Its active form, pyridoxal 5′-phosphate, serves as a coenzyme in some 100 enzyme reactions in amino acid, glucose, and lipid metabolism.[1] PLP is a cofactor in the biosynthesis of five important neurotransmitters: serotonin, dopamine, epinephrine, norepinephrine, and gamma-aminobutyric acid (GABA). PLP is also involved in the synthesis of histamine. Transaminases break down amino acids with PLP as a cofactor. The proper activity of these enzymes is crucial for the process of moving amine groups from one amino acid to another.

Which of the following is a cofactor required for the hydroxylation of lysine and proline?

Vitamin C Vitamin C deficiency primarily affects connective tissue Vitamin C is essential for the normal elaboration and maintenance of bone matrix, cartilage, and dentin

A patient 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?

Vitamin E Vitamin E is also called TOCOPHEROL Vitamin E prevents free radicals from oxidizing compounds such as polyunsaturated fatty acids It is the least toxic of the fat soluble vitamins (Vitamin D is the most toxic)

Vitamin B1 deficiency of thiamine deficiency is associated with what diseases

Wernicke encephalopathy: is the presence of neurological symptoms caused by biochemical lesions of the central nervous system after exhaustion of B-vitamin reserves, in particular thiamine (vitamin B1). Korsakoff Syndrome: is an amnestic disorder caused by thiamine deficiency (vitamin B1 deficiency) associated with prolonged use of alcohol.

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? What are the normal values for daily glomerular filtrate amount and excretion amount, respectively?

Your plasma osmolarity is lower than normal, and you will likely excrete a large amount of dilute urine • 150 to 250 L; 1-2 L 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.

Inulin

a polysaccharide completely excreted by the kidney; used to measure kidney function Inulin is uniquely treated by nephrons in that it is completely filtered at the glomerulus but neither secreted nor reabsorbed by the tubules. This property of inulin allows the clearance of inulin to be used clinically as a highly accurate measure of glomerular filtration rate (GFR) — the rate of plasma from the afferent arteriole that is filtered into Bowman's capsule measured in ml/min.

Which enzyme is derived from osteoblasts and its serum level rises in bone conditions with increased osteoblastic activity?

alkaline phosphatase Alkaline phosphatase is abundant in bone, placenta, intestine and the hepatobiliary system. Each of these organs contains a different isoenzyme. The bone and liver enzymes are the most abundant in the normal serum. The bone enzyme is derived from osteoblasts and its serum level rises in bone conditions with increased osteoblastic activity: rickets, osteomalacia, hyperparathyroidism, osteitis deformans, neoplastic diseases with bone metastases and healing fractures. Note: The liver enzyme level is increased in patients with biliary obstruction.

Starch molecules are broken down by enzymes known as?

amylases Amylase is the name given to glycoside hydrolase enzymes that break down starch into glucose molecules. Amylase is also known as ptyalin. Although the amylases are designated by different Greek letters, they all act on α-1,4-glycosidic bonds.

All G proteins exist in two forms?

an active GTP-bound form that acts on the effector and an inactive GDP-bound form that does not G proteins (guanine nucleotide-binding proteins) play a pivotal role in the signal transduction pathways for numerous hormones and neurotransmitters. The G protein is loosely bound to the cytoplasmic surface of the plasma membrane and it consists of three subunits designated α, β and ᵞ. The α subunit has a nucleotide binding site that can accommodate either GDP or GTP. β and ᵞ subunits function as a single unit, but the α subunit is only loosely associated with βᵞ. The inactive G protein is associated with the unstimulated receptor, with GDP bound to the α subunit. Hormone binding induces a conformational change both in the receptor and the attached G protein. This conformational change greatly reduces the affinity of the α subunit for GDP. GDP dissociates away and is quickly replaced by GTP. Once GTP is bound, the G protein leaves the receptor and breaks up into the α-GTP subunit and the βᵞ complex. Both the α-GTP subunit and the βᵞ complex diffuse along the inner surface of the plasma membrane, where they bind to target proteins known as effectors. background image The GTP bound a subunit of the G protein activates adenylate cyclase. Active adenylate cyclase converts ATP to cAMP. cAMP further binds and activates PKA. Active protein kinase A (PKA) phosphorylates specific proteins which up or down-regulates cellular processes depending on the cell type. The components of the activated G protein are membrane-bound messengers that transmit a signal from the receptor to the effector. All G proteins exist in two forms: an active GTP-bound form that acts on the effector and an inactive GDP-bound form that does not.

A patient of yours lists a selective β-blocker in her medication list. You know that this is for her hypertension. What is the mechanism of this drug?

blocks β1-adrenergic receptors in the heart, causing a decrease in heart rate and force of contraction β-blockers "block" the effects of adrenaline on the body's β-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. β-blockers also block the impulses that can cause an arrhythmia. The body has two main beta receptors: β1 and β2. Some β-blockers are selective, which means that they block β1 receptors more than they block β2-receptors. β1-receptors are responsible for heart rate and the strength of your heartbeat Nonselective β-blockers block both β1 and β2-receptors. β2-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: α-receptors: α1: located in sympathetic postsynaptic nerve terminals- increase vascular smooth muscle contraction α2: located in sympathetic presynaptic nerve terminals; beta cell of pancreatic islets- inhibit NE release; inhibit insulin release β-receptors: β1: located in the heart - increase cardiac output β2: located in liver; smooth muscle vasculature, bronchioles and uterus - increase hepatic glucose output; decrease contraction of blood vessels, bronchioles and uterus Important: Norepinephrine stimulates mainly α-receptors. Epinephrine stimulates both a and β-receptors.

If a patient's SA and AV nodes fail, what is the most likely situation the patient will be in? [refer to AS card 160-I for illustration]

both the atria and ventricles will continue to contract on the pace of the bundle of His (30-40 impulses per minute) The bundle of His (AV bundle) 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 ventricles. The AV node together with the bundle of His make up the AV nodal tissue. The AV nodal tissue is considered supraventricular (above the ventricles). The AV nodal tissue has an intrinsic rate of 40-60 beats per minute. If the SA node is injured, AV nodal tissue can take over control of heart rate and rhythm. The bundle of His (AV bundle) passes subendocardially down the right side of the interventricular septum for about 1 cm and then divides into the right and left bundle branches. The right bundle branch, a direct continuation of the bundle of His, proceeds down the right side of the interventricular septum. The left bundle branch, which is considerably thicker than the right, arises almost perpendicular from the bundle of His and perforates the interventricular septum. On the subendocardial surface of the left side of the interventricular septum, the left bundle branch splits into a thin anterior division and thick posterior division. The right bundle branch and the two divisions of the left bundle branch ultimately subdivide into a complex network of conducting fibers, called Purkinje fibers that spread out over the subendocardial surfaces of both ventricles. Collectively, the bundle branches and Purkinje network comprise the ventricular conduction system. Note: 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 activity at a rate of 30-40 impulses per minute. If the SA and AV nodes are injured, the ventricular conducting system can take over control of heart rate and rhythm.

The carbonic acid formation by the conversion of CO2 and H2O during aqueous humor production is catalyzed by which of the following enzymes?

carbonic anhydrase Carbonic anhydrase (CA) is a zinc-containing enzyme that catalyzes the reversible reaction involving hydration of carbon dioxide and dehydration of bicarbonate. The enzyme is present in high concentration in the red blood cells, gastrointestinal mucosa, kidney tubules, and epithelial cells of many glands.

A peptide bond forms between the ______ group of one amino acid and the ______ group of the adjacent amino acid.

carboxyl; amino Amino acids are joined together in proteins by peptide bonds. 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.

An electrocardiogram is a graphic illustration of the:

cardiac conduction system 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: The P wave is the electrical recording from the body surface of atrial depolarization and precedes atrial contraction. The T wave of an electrocardiogram wave segment represents the repolarization of the ventricles. The QRS complex represents ventricular depolarization. The first heart sound represents closure of the AV valves at the onset of systole. 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. background image An ECG that shows extra P waves before each QRS complex indicates partial heart block (or second-degree block). 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.

All preganglionic neurons are ________in both the sympathetic and the parasympathetic nervous systems.

cholinergic All preganglionic neurons are cholinergic in both the sympathetic and the parasympathetic nervous systems. Either all or almost all of the postganglionic neurons of the parasympathetic system are also cholinergic. Conversely, most of the postganglionic sympathetic neurons are adrenergic, except for the postganglionic sympathetic nerve fibers to the sweat glands, to the piloerector muscles of the hairs and to a very few blood vessels which are cholinergic. Note: Those fibers that secrete acetylcholine are said to be cholinergic. Those that secrete norepinephrine are said to be adrenergic. 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

Which of the following components of the electron transport chain accepts only electrons?

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 that 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).

monosynaptic reflex

direct communication between sensory and motor neuron

Iron, the most important mineral in the formation of hemoglobin, is absorbed mainly in the __________ and is only absorbed as ___________. -ascending colon, Fe3+ -sigmoid colon, Fe2+ -duodenum, Fe2+ -jejunum, Fe2+

duodenum, Fe2+ Iron is quantitatively the most important trace element Approximately 75% of the total amount is found in her proteins, mainly hemoglobin and myoglobin Iron is absorbed 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

Normally, which phase would have the highest ventricular pressure?

ejection phase (isovolumetric contraction would have an increasing pressure right up until the ejection where the pressure would be the highest

Trypsinogen is activated either by trypsin or by the duodenal enzyme:

enteropeptidase The presence of amino acids (from protein digestion) in the small intestine (specifically the duodenum) stimulates the release of cholecystokinin (CCK). This hormone causes the release of the pancreatic zymogens (e.g., trypsinogen, chymotrypsinogen, proelastase, procarboxypeptidases and prophospholipases) and the contraction of the gallbladder to deliver bile to the duodenum. Trypsinogen is activated either by trypsin or by enteropeptidase Trypsin converts trypsinogen, chymotrypsinogen, proelastase and procarboxypeptidase A and B to their active forms. Important point: Trypsin can act as an activator for all zymogens of pancreatic proteases.

weak bonds

hydrogen bonds, ionic bonds, van der waals forces, hydrophobic interactions 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 (α-helix and β-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.

Patients with vitamin C deficiency (scurvy) form a collagen with insufficient:

hydroxyproline The hydroxylation of prolyl and lysyl side chains in procollagen requires ascorbic acid (vitamin C). As a result, patients with vitamin C deficiency (scurvy) form a collagen with insufficient hydroxyproline that denatures spontaneously at room temperature. Collagen accounts for approximately 25% of the body protein in adults and 15% to 20% in children. It is most abundant in strong, tough connective tissues. Type I collagen is by far the most abundant collagen in the body. It has a most unusual amino acid composition, with 33% glycine and 10% proline. It also contains hydroxyproline and hydroxylysine.

hypertonic solution

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 cell 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. 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.

Releasing hormones are synthesized in the:?

hypothalamus

A competitive inhibitor of an enzyme:

increases Km without affecting Vmax Inhibitor and substrate compete for the same binding site on the enzyme • Vmax remains the same • Is overcome by increasing substrate • Km is increased

stretch reflex

involuntary contraction of a muscle due to rapid stretching of that muscle A typical example of a stretch reflex is the patellar or knee jerk reflex that elicits a knee jerk upon tapping on the patellar tendon

The bicuspid or mitral valve is located between which two chambers of the heart?

left atrium and left ventricle

Oxidation

loss of electrons

Von Gierke's Disease

most common glycogen storage disease defect in glucose 6 phosphatase leads to periods of very low blood sugar between meals needs continuous feeding to maintain blood sugar levels glucose 6 phosphate builds up in the cell and cannot be broken down into glucose - so the liver enlarges and is damaged over time Glycogen storage disease type I (GSD I) is an inherited disease that results in the liver being unable to properly break down stored glycogen. This impairment disrupts the liver's ability to break down stored glycogen that is necessary to maintain adequate blood sugar levels. GSD I is divided into two main types, GSD Ia and GSD Ib, which differ in cause, presentation, and treatment. GSD Ia is caused by a deficiency in the enzyme glucose-6-phosphatase, while GSD Ib is caused a deficiency in the enzyme glucose-6-phosphate translocase.

Thick filaments are composed of

myosin

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__________.

neuromuscular junction, motor end plates, acetylcholine

The two classes of acetylcholine receptors in autonomic ganglia are:

nicotinic and muscarinic The main type of neuron in autonomic ganglia is the postganglionic neuron. These cells receive synaptic connections from preganglionic neurons and they project to autonomic effector cells. The classic neurotransmitter of autonomic ganglia, whether sympathetic or parasympathetic, is acetylcholine. The two classes of acetylcholine receptors in autonomic ganglia are: Nicotinic Receptors Stimulated by ACh and nicotine, not stimulated by muscarine Found at all ganglionic synapses Also found at neuromuscular junctions and the adrenal medulla Produce excitation The fast EPSP (excitatory postsynaptic potentials) results from activation of nicotinic receptors, which cause ion channels to open Blocked by hexamethonium and curare Muscarinic Receptors Stimulated by ACh and muscarine, not stimulated by nicotine Found at target organs when ACh is released by postganglionic neurons (all of parasympathetic and some sympathetic) including heart, smooth muscle and glands The slow EPSP is mediated by muscarinic receptors that inhibit the M current, a current produce by conductance of potassium Blocked by atropine Note: Those fibers that secrete acetylcholine are said to be cholinergic. Those that secrete norepinephrine are said to be adrenergic. 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. Important: All preganglionic neurons are cholinergic in both the sympathetic and the parasympathetic nervous systems. Either all or almost all of the postganglionic neurons of the parasympathetic system are also cholinergic. Conversely, most of the postganglionic sympathetic neurons are adrenergic, except for the postganglionic sympathetic nerve fibers to the sweat glands, to the piloerector muscles of the hairs, and to a very few blood vessels which are cholinergic.

Which of the following patients has the least chance of edema formation?

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.

Hematocrit

percentage of blood volume occupied by red blood cells

serum

plasma without clotting factors Plasma contains no cells

chondroitin sulfate

provides support and adhesiveness in cartilage, bone, skin, and blood vessels Most abundant glycosaminoglycans

Reabsorption of glomerular filtrate would be most affected if modifications were made to the permeability of which section of the nephron?

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. Excretion Rate = Filtration Rate - Reabsorption + Secretion

The kidneys regulate acid-base balance by the:

secretion of hydrogen ions into the renal tubules and the reabsorption of bicarbonate ions There are three primary systems that regulate the hydrogen ion concentration in the body fluids: 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. The respiratory center, which regulates the removal of CO2 (and therefore H2CO3) from the extracellular fluid. The kidneys, which can excrete either acid or alkaline urine, thereby readjusting the extracellular fluid hydrogen ion concentration toward normal during acidosis or alkalosis. *** The kidneys, although providing the most powerful of all the acid-base regulatory systems, require many hours to several days to readjust the hydrogen ion concentration.

Fibrinogen

soluble protein present in blood plasma, from which fibrin is produced by the action of the enzyme thrombin. Fibrinogen (factor I) is a glycoprotein complex, made in the liver, that circulates in the blood of all vertebrates. During tissue and vascular injury, it is converted enzymatically by thrombin to fibrin and then to a fibrin-based blood clot. Fibrin clots function primarily to occlude blood vessels to stop bleeding.

AUG

start codon The start codon codes for methionine

In contrast to hemoglobin and myoglobin where the iron is always in the ferrous state (Fe2+), the heme iron of the cytochromes:

switches back and forth between Fe2+ and Fe3+ The cytochromes contain iron in the form of an iron-porphyrin, usually the heme group. In contrast to hemoglobin and myoglobin where the iron is always in the ferrous state, the heme iron of the cytochromes switches back and forth between Fe2+ (ferrous) and Fe3+ (ferric) states. Also in most cytochromes (but not cytochrome a/a3), the heme iron is bound to two amino acid side chains rather than one. This prevents the binding of molecular oxygen, carbon monoxide and other potential ligands.

Which of the following parameters is decreased during exercise?

total peripheral resistance (TPR) 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.

The action potential is generated by the rapid opening and subsequent voltage inactivation of voltage-dependent ______ channels and the delayed opening and closing of voltage-dependent ______ channels.

• Na+, K+ The action potential is generated by the rapid opening and subsequent voltage inactivation of voltage-dependent Na+ channels and the delayed opening and closing of voltage-dependent K+ channels.

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

The primary functional unit of the sympathetic and parasympathetic nervous systems is the: [refer to AS card 212-I, 212 A-I for illustration]

• two-neuron motor pathway Remember: The primary functional unit of the sympathetic and parasympathetic nervous systems is the two-neuron motor pathway, which consists of a preganglionic neuron, whose cell body is located in the CNS, and a postganglionic neuron, whose cell body is located in one of the autonomic ganglia.