Endocrine system/metabolism - unit two bio/biochem MCAT

What are the four process that occur in aerobic respirations?

1. glycolysis 2. pyruvate decarboxylation 3. Citric Acid Cycle (also called the TCA cycle or KREBS cycle) 4. Electron transport chain

What are the 8 endocrine glands?

1. hypothalamus 2. pituitary- anterior and posterior 3. thyroid 4. parathyroid- involved in calcium regulation 5. adrenal gland - cortex: makes things like cortisol - medulla: epinephrine 6. Pancreas 7. gonads (ovaries and testes) 8. pineal gland

The endocrine system consists of organs, known as glands, that secrete hormones. Hormones are signaling molecules that are secreted directly into the bloodstream to distant target tissues. At target tissues, hormones bind to receptors, inducing a change in gene expression or cellular functioning. Not all hormones share the same structure and function. In order to understand how each hormone functions, it is first important to understand basic hormone structure. Hormones can be subdivided into three categories based on different criteria. What are the three different hormone categories based on their chemical identities?

1. peptide hormones. 2. steroid hormons 3. amino acid derivatives (also known as amine hormones)

What is the role of the parathyroid gland?

Four spots that are collectivity known as the parathyroid glands are located right behind the thyroid gland in the neck. Its main role is regulating the body's blood calcium level through the parathyroid hormone (PTH) - the level of calcium in our body is hugely important bc calcium has many roles such as muscle contraction, bone growth, etc. And all of those functions are really sensitive to the level of calcium that is floating around in our body.

what is the role of glucagon? when is it released?

Mnemonic: Glucagon levels are high when glucose is gone

What are the roles of T3 and T4? what occurs when T3 and T4 levels are increased? decreased?

triiodothyronine (T3) and thyroxine (T4) are both produced by the iodination of the amino acid tyrosine in the follicular cells of the thyroid. The numbers 3 and 4 refer to the number of iodine atoms attached to the tyrosine. Thyroid hormones are capable of resetting the basal metabolic rate of the body by making energy production more or less efficient, as well as altering the utilization of glucose and fatty acids. Increased amounts of T3 and T4 will lead to increased cellular respiration. this leads to increased protein and fatty acid turnover by speeding up both synthesis and degradation of these compounds. High plasma levels of thyroid hormones will lead to decreased TSH and TRH synthesis; negative feedback prevents excess secretion of T3 and T4 as shown in the pic.

What are the three classes of hormones based on their function?

1. Autocrine hormones 2. Panacrine hormones 3. Endocrine hormones

what is hypothyroidism? hyperthyroidism?

A deficiency of iodine or inflammation of the thyroid may result in hypothyroidism, in which thyroid hormones are secreted in insufficient amounts or not at all. The condition is characterized by lethargy, decreased body temp, slowed respiration and heart rate, cold intolerance, and weight gain. Thyroid hormones are required for appropriate neurological and physical development in children. Most children are tested at birth for appropriate levels bc a deficiency will result in intellectual disability and developmental delay (cretinism) An excess of thyroid hormones, which may result from a tumor or thyroid overstimulation, is called hyperthyroidism. We can predicts the clinical course of this syndrome by considering the opposite of each of the effects seen in hypothyroidism; heightened activity level, increased body temp, increase respiratory and heart rate, heat intolerence, and weight loss.

What are steroid hormones? can they travel freely in the blood stream? are their effects short or long lived? can they pass through the plasma membrane freely?

Derivative of Cholesterol 1. Cortisol 2. Aldosterone 3. Testosterone 4. Estradiol 5. Cholesterol are all very hydrophobic (not water soluble), so they CANNOT travel freely in the blood. They need the help of binding proteins. BUT they can travel through the plasma membrane easily considering they are nonpolar molecules. Hense there receptors are usually located in the intracellular (in the cytosol) or intranuclear (in the nucleus) - note that hormones are generally inactive while attached to a carrier protein and must dissociate fro the carrier to function. Therefore, levels of carrier proteins can change the levels of active hormones. Generally lead to slow acting, longer lasting effects. KEY CONCEPT: peptide hormones have surface receptors and act via second messenger systems. Steroid hormones bind to intracellular receptors and function by binding to DNA to alter gene expression. Mnemonic: Insulin is a peptide hormone, and it has to be released at every meal in order to be active. Thus, it has a fast onset but it short lived (like most peptide hormones). Estrogen and testosterone are steroid hormones that promote sexual maturation. This is a slower, but longer lasting change (as is true for most steroid hormones)

Now turning our attention to the four other hormones that have tropic effects in the body. What causes the release of the four tropic hormones from the anterior pituitary and what are their effects?

FLAT are the four tropic hormones released from the anterior pituitary.

Overall what is the net results from the citric acid cycle? How much ATP is made from NADH? FADH2?

For one glucose (which is 2 acetyl CoA molecules or two rounds of the citric acid cycle) 6 NADH 2 FADH2 2 ATP 4 CO2 the majority of the CO2 we exhale comes from this cycle.

what is the role of growth hormone? what is gigantism? dwarfism? acromegaly? when is it released? when is it not released?

GHRH from the hypothalamus stimulates GH from the anterior pituitary gland. Somatostatin (SST) inhibits GH secretion. Its release is stimulated by starvation (protein deficiency), fasting (hypoglycemia), stress, exercise, and excitement. GH acts directly on target tissues and as a trophic hormone to the liver, which releases Insulin-like Growth Factor (IGF). GH is names for exactly what it does: it promotes the growth of bones and muscle. This sort of growth is energetically expensive and requires large quantities of glucose. Growth hormone prevents glucose uptake in certain tissues (those that are not growing) and stimulates the breakdown of fatty acids. This increase the availability of glucose overall, allowing for muscles and bone to use it. GH release is stimulated by GHRH from the hypothalamus. Bone growth originates in special regions of the bone known as epiphyseal plates, which seal shut during puberty. An excess of GH release in childhood (before this closer) can cause gigantism, and a deficit results in dwarfism. In adults, the situation is slightly different. Bc the long bones are sealed, GH still has an effect but it is primarily in the smaller bones. The resulting medical condition is known as acromegaly. The bones most commonly affected are those in the hands, feet, and head. Patients with acromegaly tend to seek medical help bc they have had to buy larger shoes, cannot wear rings, and can no longer fit into their hats.

What is glycolysis? where does it occur? what goes in/comes out?

Glucose --> (2) Pyruvate + 2 ATP + 2 NADH All cells carry out glycolysis. Bc all cells carry out glycolysis it has to occur in an area that all cells have - hence it occurs in the cytoplasm. One glucose (which is a 6 carbon sugar) is broken down into (2) pyruvate (which is a 3 carbon sugar). In this process 2 ATP and 2 NADH molecules are produced. If the cell has mitochondria and oxygen the energy carriers from glycolysis (NADH) can feed into the aerobic respiration pathway. If they do not have either mitochondria or oxygen (such as in erythrocytes (RBC) or exercising skeletal muscle, respectively) glycolysis may occur anaerobically, although some of the available energy is lost (i.e. fermentation) Glycolysis is the first step of cellular respiration - the process by which sugars that have been consumed are converted into useful energy. ALSO NOTE: while glucose represents the primary monosaccharide use by cells, other monosaccharides such as galactose and fructose can also contribute to ATP production by feeding into glycolysis or other metabolic processes. SO OVERALL 1. location: cytoplasm 2. Input: glucose (6-C) output: (2) pyruvate (3-C) 3. ATP: 2 NADH:2

what are the functions of NADPH? is it the same as NADH?

KEY CONCEPT: NADPH and NADH are not the same thing. NAD+ is an energy carrier; NADPH is used in biosynthesis, in the immune system, and to help prevent oxidative damage

What is the function of the pancreas? what cells does it contain and what hormones do they secrete?

Located in the upper part of the abdomen and it is involved in the regulation of blood sugar. It does this through the hormones insulin and glucagon. The pancreas is vitally important bc without insulin and glucagon we can't regulate how much sugar is in our body's blood verse the cells which could lead to major diseases like diabetes. The pancreas has both exocrine and endocrine functions. Exocrine tissues secrete substances directly onto ducts; the pancreas produces a number of digestive enzymes, as discussed in ch 9 bio. From an endocrine standpoint, small clusters of hormone-producing cells are groups together into isles of langerhans throughout the pancreas, as shown in the pic. Islets contain three distinct types of cells: alpha (α) beta (β), and delta (δ) cells. Each cell type secretes a different hormone: α cells secrete glucagon, β cells secrete insulin, and δ cells secrete somatostatin.

What are glucocorticoids?

OVERVIEW 1. Hypothalamus senses low glucocorticoid levels in the blood- 2. Releases CRF (corticotropin releasing factor) to pituitary gland 3. Pituitary releases ACTH (Adrenocorticotropic hormone) 4. ACTH travels to adrenal cortex and tells it to release glucocorticoids 5. Glucocorticoids support BP, GI functions, Mental Functions, Help control the immune response mechanisms

What is the role of the hypothalamus?

OVERVIEW - Maintains homeostasis - Regulates temperature, heart rate, blood pressure - Governs emotional behaviors - Secretes hormones that act on pituitary gland it is the control center of the endocrine system and its located in the forebrain above the pituitary gland and below the thalamus In addition to acting out the pituitary gland (which we will get into) it actually makes some hormones itself. It makes ADH and oxytocin - ADH (also called vasopressin) is the antidiuretic hormone and it's a main regulator of our fluid volume in our body. It increases reabsorption of water in the collecting ducts of the kidneys. ADH is secreted in response to increased plasma osmolarity, or increased concentration of solutes within the blood. - Oxytocin is a hormone that stimulates the uterus to contract for females during pregnancy - it also secretes 5 other hormones which act on the anterior pituitary gland. These hormones are all tropic hormones. 1. Gonadotropin-releasing hormone (GnRH) 2. Growth hormone-releasing hormone (GHRH) 3. Somatostatin (SST) also known as GHIH 4. Thyroid-releasing hormone (TRH) 5. Dopamine (DA) also known as Prolactin-inhibiting factor (PIF) 6. Corticotropin-releasing hormone (CRH) SIDE NOTE: the hypothalamus interacts with the two sections of the pituitary gland in different ways. - it interacts with the anterior pituitary via tropic hormones. The hypothalamus secretes hormones in to the hypophyseal portal system, which is a blood vessel system that directly connects the hypothalamus with the anterior pituitary. Thus, hormones from the hypothalamus travel directly to the anterior pituitary and can not be found in appreciable concentrations in the systemic circulation. Also note that the hypophysis is an alternative term for the pituitary. Once hormones have been released from the hypothalamus in to this portal bloodstream, they travel down the pituitary stalk and bind to receptors in the anterior pituitary, stimulating the release of those hormones. - on the other hand, the posterior pituitary does not receive tropic hormones through the hypophyseal portal system. Rather, neurons in the hypothalamus send their axons down the pituitary stalk directly in to the posterior pituitary, which can then release oxytocin and ADH. BRIDGE: the hypothalamus contains a number of nuclei in its three sections, called the lateral, ventromedial, and anterior hypothalamus. These nuclei play roles in emotional experience, aggressive behavior, sexual behavior, metabolism, temp regulation, and water balance

What is the role of the adrenal glands?

OVERVIEW - Sit on top of kidneys, each one made of the adrenal cortex (outer part) and adrenal medulla (inner region) - Hormones released by adrenal CORTEX are vital for life, unlike ones released by adrenal medulla - Cortex produces cortisol, regulating and supporting # of functions e.g. cardiovascular and anti-inflammatory → Cortex also produces aldosterone (rest. for maintaining blood volume and pressure) - Medulla releases adrenaline and noradrenaline (helps fight or flight response by increasing heart rate and blood flow + constriction blood vessels = higher blood pressure) The adrenal glands are located right on top of the kidneys. We can further divide the adrenal glands into two parts, the outer part is the cortex and the inner part is the medulla. The reason for the distinction is bc the inside and outside of the adrenal glands have two different functions. - the adrenal cortex secretes corticosteroids. these are steroid hormones that can be divided into three functional classes: glucocorticoids, mineralocorticoids, and cortical sex hormones. - the two major steroids made in the adrenal cortex are cortisol and aldosterone. Cortisol is one of the body's stress hormones. so it functions to increase blood sugar in times of stress so we have energy, and it also has some anit-inflammatory functioning. and then aldosterone is one of the major regulating hormones of our body's blood volume and how much fluid is in our veins and arteries. - The medulla makes a class of hormones called catecholamines. The two major ex of catecholamines are epinephrine and norepinephrine. Sometimes epinephrine is called adrenaline. These catecholamines are really involved in our body's fight or flight response.

Our body is composed of a lot of different parts. There are a lot of organ systems, each of which has organs, and all of those organs are made of tissues, and those tissues are made up of cells. But how do all of these different parts communicate?

Our body can communicate with all of the different parts either through electrical signals or chemical signals One of the ways these parts communicate is through the nervous system and through the pre-laid tracks of nerves. - but not every part of the body is connected by nerves. For ex. How would the brain go about communicating with part of the kidney? there isn't a nerve directly connecting the two. Therefore the other way is through the endocrine systems. - the endocrine system is a system of organs that are called glands. And those glands secrete little chemical messages called hormones. These hormones are released into the bloodstream so that they can circulate from one part of the body to another parts of the body in order to initiate an effect. Glands --> hormones --> effect The endocrine system has many different glands one of the major endocrine glands is the hypothalamus - the hypothalamus is located in the forebrain, and as a member of the brain it receives a lot of signals form the nervous system. So those signals from the nervous system are funneling into the brain and the hypothalamus then, as a kind of dual member of the endocrine system, funnels those signals into the pituitary glands. Bc of this duel role between the nervous system and the endocrine system, it often gets the tagline as the control center of the endocrine system.

What is the role of the parathyroid hormone (PTH)?

PTH is secreted by the parathyroid in response to decreased plasma Ca2+ levels. It acts on bone, kidney, and intestines to increase Ca2+ back to normal. The hormone produced by the parathyroid gland is aptly named parathyroid hormone (PTH). PTH serves as an antagonistic hormone to calcitonin, raising blood calcium levels; specifically , it decreased excretion of calcium by the kidneys, increasing absorption of calcium in the gut (via vitamin D), and increases bone resorption, thereby freeing up freeing up calcium, as shown in the pic. Like the hormones we have already seen, PTH is also subject to feedback inhibition. As levels of plasma calcium rise, PTH secretion is decreased. Parathyroid hormone also promotes phosphorus homeostasis by increasing the resorption of phosphate from bone and reducing reabsorption of phosphate in the kidney (thus promoting its excretion in the urine) PTH also activates vitamin D, which is required for the absorption of calcium and phosphate in the gut. The overall effect of PTH, therefore, is a significant increase in blood calcium levels with little effect on phosphate (the absorption of phosphate in the gut and its excretion in the kidney somewhat cancel each other.) KEY CONCEPT: Just like glucagon and insulin, PTH and calcitonin are antagonistic to each other. We should think of these hormones as a pair with the primary function of regulating calcium levels in the blood. PTH increases serum calcium levels, whereas calcitonin decrease calcium levels.

What are peptide hormones? what are the hormones that fall under the group peptide and protein hormones? can they travel freely in the blood?

Peptide hormones are made up of amino acids, ranging in size from quite small (such as ADH) to relatively large (such as insulin). made in a version called a pro-hormone first which gets packaged and cleaved to become an activated hormone in the golgi ex. Insulin, Glucagon, TRH, CRH, GHRH, GH, ACTH, Prolactin, FSH, LH, ADH, Oxytocin Do not usually need binding proteins to travel through the blood (hence you can say they are hydrophilic) BUT there are unable to cross the plasma membrane on their own considering they are charged molecules. Instead, they must act through a second messenger system - known as a signaling cascade where at each step there is a possible amplification. Some common second messengers are cyclic adenosine monophosphate (cAMP), inositol triphosphate (IP3), and calcium. The effects of peptide hormones are usually rapid but short-lived bc these hormones act through second messenger cascades, which are transient. It is quicker to turn them on or off compared with steroid hormones, but their effects do not last without relatively constant stimulation Bc peptide hormones are generally water-soluble, peptide hormones can travel freely in the bloodstream and usually do not require carriers. This is in stark contrast to steroid hormones, which are lipid-soluble.

We are going to first discuss the role of the anterior pituitary direct hormones. What is the role of prolactin? what causes its release?

Prolactin stimulates breast development and milk production. When the hypothalamus is releasing pattern-prolactin-inhibiting factor (PIF), which is actually dopamine, prolactin secretion is inhibited or decreased. BUT when dopamine (PIF) is not being released from the hypothalamus, the block is removed from the anterior pituitary and it will begin releasing prolactin. Prolactin is more important in females than in males; it stimulates milk production in the mammary glands. Milk production in the male is always pathologic. During pregnancy, estrogen and progesterone levels are high. In addition, prolactin, a hormone that increases milk production, is also secreted by the anterior pituitary. Prolactin is an unusual hormone in that the release of dopamine from the hypothalamus decreases its secretion. The high levels of estrogen and progesterone allow for the development of milk ducts in preparation for lactation, but it is not until shortly after the expulsion of the placenta, when estrogen, progesterone, and dopamine levels drop, that the block on milk production is removed and lactation actually begins. Milk ejection occurs when the newborn infant latches on to the breast. Nipple stimulation causes activation of the hypothalamus (through the nervous system) resulting in two different reactions. 1. first oxytocin is released from the posterior pituitary, resulting in contraction of the smooth muscle of the breast and ejection of milk through the nipple. 2. second, the hypothalamus stops releasing dopamine onto the anterior pituitary, which allows prolactin release, causing the milk and regulation of the milk supply.

What is pyruvate decarboxylation?

Pyruvate(3-C) --> Aceytl CoA (2-C) + CO2 + NADH Pyruvate needs to enter the mitochondria where it can continue aerobic respiration therefore we need to "decarboxylate" it, hence pyruvate losses a carboxyl group (C=O) forming Acetyl CoA and CO2. Acetyl CoA can then either enter the citric acid cycle if ATP is needed or can be used for fatty acid synthesis if sufficient ATP is present 1. Location: Mitochondrial Matrix 2. Input: Pyruvate (a 3 carbon molecule) output: Acetyl CoA (a 2 carbon molecule) 3: NADH: 1 CO2: 1 ALSO NOTE: once pyruvate is produced it has 3 fates 1. conversation to Acetyl CoA by pyruvate dehydrogenase if ATP is needed 2. conversation to lactate by lactate dehydrogenase if no O2 is present 3. conversation to oxaloacetate by pyruvate carboxylase. This occurs when glucose is needed. Oxylaoacetate can feed into gluconeogenesis which is a metabolic pathway that results in the generation of glucose from certain non-carbohydrate carbon substrates.

What is gluconeogenesis and where does it occur?

Synthesis of glucose from non-carbohydrate substrates. Primarily in the liver. glycogenolysis and gluconeogenesis are promoted by glucagon and epinephrin with act to raise blood sugar levels and are inhibited by insulin which cants to lower blood sugar levels. During fasting, glycogen reserves drop dramatically in the first 12 hours, during which time gluconeogenesis increases. After 24 hours, it represents the sole rouse of glucose. Important substrates from gluconeogenesis are: - glycerol 3-phosphate (from stored fats, or triacylglycerols, in adipose tissue) - lactate (from anaerobic glycolysis) - glucogenic amino acids (from muscle proteins)

what hormones does the anterior pituitary release?

The AP produces 7 hormones. (all of which are protein/peptide hormones) 1. Follicle-stimulating hormone (FSH) 2. Luteinizing hormone (LH) 3. Adrenocorticotropic hormone (ACTH) 4. Thyroid-stimulating hormone (TSH) 5. Prolactin 6. Endorphines 7. Growth hormone (GH) four of these hormones are tropic and three are direct. MNEMONIC: FLAT PEG the four hormones in FLAT are all tropic and the three in PEG are direct KEY CONCEPT: whereas most hormones in the anterior pituitary require a factor from the hypothalamus to be released, prolactin is an exception. As long as the hypothalamus releases PIF (which is actually dopamine) not prolactin will be released. It is the absence of PIF that allows prolactin to be released. ALSO the pituitary gland it's known as the "master gland" bc it takes the stimulation from the hypothalamus and directs it to all of the other endocrine glands. Therefore, their function is ultimately dependent on the pituitary gland working well.

What is the citric acid cycle? where does it occur?

The citric acid cycle, also called the Krebs cycle or the tricarboxylic acid (TCA) cycle, occurs in the mitochondrial matrix. The main function of the cycle is the oxidation of Acetyl CoA to CO2 and H2O. In addition, the cycle produces the high energy electron carrying molecules NADH and FADH2. GTP is also produced which can be converted to ATP. Acetyl CoA can be obtained from the metabolism of carbohydrates, fatty acids, and amino acids, all of which converge on the final common pathway of the citric acid cycle. Acetyl CoA can be formed the following ways 1. fatty acid oxidation (β oxidation) 2. amino acid catabolism - certain amino acids (ketogenic amino acids) can lose their amino group via transamination which forms ketone bodies. These ketone bodies can then be converted to Acetyl CoA. [while the brain normally uses glucose for energy, under conditions such as starvation, ketone bodies can become the brain's major source of energy] 3. Pyruvate Dehydrogenase

What is the role of oxytocin and ADH? what causes there release?

The posterior pituitary contains the nerve terminals of neurons with cell bodies in the hypothalamus. As mentioned easier, the posterior pituitary receives and stores two hormones produced by the hypothalamus: ADH and oxytocin. ADH is secreted in response to low blood volume (as sensed by baroreceptors) or increased blood osmolarity (as sensed by osmoreceptors), as shown in the pic. Its action is at the level of the collecting duct, where it increase the permeability of the duct to water. This increases the reabsorption of water from the filtrate in the nephron. This results in greater retention of water, which results in increased blood volume and higher blood pressure. Oxytocin is secreted during childbirth and allows for coordinated contractions of uterine smooth muscle. Its secretion many also be stimulated by sucking, as it promotes milk ejection through contraction of smooth muscle in the breast. Finally, oxytocin may be involved in bonding behavior. Oxytocin is unusual in that it has a positive feedback loop; the release of oxytocin promotes uterine contractions, which promotes more oxytocin release, which promotes stronger uterine contractions, and so on. Positive feedback loops can usually be identified by a spiraling forward scheme and usually have definitive endpoint - in their case, delivery. KEY CONCEPT: the two hormones released from the PP are actually synthesize in the hypothalamus and simply released form the PP gland. The PP does not synthesize any hormones itself.

What is the role of the thyroid gland? what hormones does it release and when?

The thyroid gland it located in your neck and it is under the control of the anterior pituitary gland. It is controlled by the thyroid-stimulating hormone (TSH) which is released from the anterior pituitary gland. The thyroid gland has two major functions: setting basal metabolic rate and promoting calcium homeostasis. It mediated the first by releasing triiodothyronine (T3) and thyroxine (T4), while it carries out the second effect through the release of calcitonin. this role of regulating the body's metabolism is crucial bc that's how our body gets energy.

What is the pentose phosphate pathway?

also called the hexose monophosphate shunt (HMP) occurs in the cytoplasm of most cells, generating NADPH and sugars for biosynthesis (derived from ribose 5-phosphate) generates ribose-5-phosphate for nucleotide synthesis and NADPH for reducing power in anabolic pathways such as fatty acid synthesis.

what are cortical sex hormones?

androgens and estrogens

how are amino acid derivative hormones synthesized?

are made by modifying amino acids, such as the addition of iodine to tyrosine (in thyroid hormone production)

What is glycogenolysis?

breakdown of glycogen to glucose

what is the role of calcitonin? when is it released?

calcitonin is released from parafollicular cells (c cells) in the thyroid gland in response to high levels of calcium in the blood. If we were to examine thyroid tissue used a light microscope, we would see two distinct cell populations within the gland. Follicular cells produce thyroid hormones and C-cells (also called parafollicular cells) produce calcitonin Calcitonin decreased plasma calcium levels in three ways: by increasing calcium excretion from the kidney, by decreasing calcium absorption from the gut, and by increasing storage of calcium in the bone. High levels of calcium in the blood simulates secretion of calcitonin from the C-cells. Mnemonic: Calcitonin tones down calcium levels in the blood KEY CONCEPT: calcium is an exceptionally important ion. The critically important functions of calcium include: - bone structure and strength - release of neurotransmitters from neurons - regulation of muscle contraction - clotting of blood (calcium is a cofactor) In addition, calcium also plays role in cell movement and exocytosis or cellular material

endocrine hormones

chemicals secreted by endocrine glands directly into the blood and function at a distance

What are amine hormones (amino acid derivative hormones)? can they travel freely in the blood? where are their receptors located? what are some examples? are their effects short or long lived?

derivatives of tyrosine - Thyroid hormones need binding proteins to help them travel in the blood 1. Thyroxine (T4) 2. Triiodothyronine (T3) 3. Norepinephrine 4. Epinephrine 5. Dopamine thyroid hormones Catecholamine Biogenic Amines

We can also classify hormones by target tissue - what are direct hormones? tropic hormones?

direct hormones: are secreted into the blood stream and travel to a target tissue, where they have a direct effect tropic hormones: cause secretion of another hormone that then travels to the target tissue to cause an effect.

What is the role of endorphins released from the anterior pituitary?

endorphins decrease the perception of pain. for ex. after completing a marathon, many people will say they are on an endorphin "high" or "rush". endorphins mask the pain from having run 26.2 miles and can even induce a sense of euphoria (a feeling or state of intense excitement and happiness.) Many pharmaceutical agents, such as morphine, mimic the effect of these naturally occurring pain killers.

what is glycogenesis?

formation of glycogen from glucose glycogen is a branched polymer of glucose and it is how glucose is stored. Glycogen synthesis and degradation occur primarily in the liver and skeletal muscles, although other tissues short smaller quantities. Involves glycosyl α-1,4 and the branching enzyme α-1,6 transferase MNEMONIC: α-1,4 keeps the same branch moving "4ward"; α-1,6 (one-six) "puts a branch in the mix" insulin and ATP increase glycogenesis epinephrine, glucagon (liver) , and AMP (muscles) inhibit it.

panacrine hormones

function regionally and act on near by cells for example of this is the topic hormones released from the hypothalamus that act on the pituitary gland

what is the role of insulin? when is it secreted?

insulin is antagonistic to glucagon and is therefore secreted when blood glucose levels are high, as shown in the pic. Insulin induces muscle and liver cells to take up glucose and store it has glycogen for later use. In addition, bc it is active when glucose levels are high, insulin stimulates anabolic processes such as fat and protein synthesis. KEY CONCEPT: insulin decrease plasma glucose. Glucagon increases plasma glucose. Growth hormone, glucocorticoids, and epinephrine are also capable of increasing plasma glucose. These hormones that raise blood glucose levels are commonly called counterregulatory hormones.

autocrine hormones

local hormones that are secreted and bind to the same cell

What are mineralocorticoids?

mineralocorticoids are used in salt and water homeostasis; their most profound effects are on the kidneys. The most noteworthy mineralocorticoid is aldosterone, which increase sodium reabsorption in the distal convoluted tubule and collecting duct of the nephron. Water follows the sodium cations into the bloodstream, increasing blood volume and pressure. Since water and sodium ions flow together, plasma osmolarity remains unchanged; this is in contrast to ADH, which only increases water reabsorption (decreasing plasma osmolarity). Aldosterone also decreases the reabsorption of potassium and hydrogen ions in these same segments of the nephron, promoting their excretion in the urine. Unlike the glucocorticoids, aldosterone is primarily under the control of the renin-angiostensin-aldosterone system, as shown in the pic. Decreased blood pressure causes the juxtaglomerular cells of the kidney to secrete renin, which cleaves an inactive plasma protein, angiotensinogen, to its active form, angiotensin I. Angiotensin I is then converted into angiotensin II by angiotensin-converting enzyme (ACE) in the lungs. Angiotensin II stimulated the adrenal cortex to secrete aldosterone. Once blood pressure is restored, there is a decrease drive to stimulate renin release, thus serving as the - feedback mechanism for this system.

What are the complexes in the ETC and what enters at each complex?

pg 366 biochem book

regulation

pg 373 also question 10.4 #1

What occurs in the electron transport chain? where does it occur? what goes in/comes out?

the ETC is the final common pathway of aerobic respiration that utilized the harvested electrons from different fuels in the body. It is important to make the distinction that it is not the flow of electrons but the proton gradient it generates that ultimately produces ATP. The ETC is a series of oxidation-reduction reactions that transfer high energy electrons all the way down the chain to oxygen. O2 is the final electron acceptor in the ETC. NADH and FADH2 are electron donors and oxygen is the electron acceptor. The final step of aerobic respiration is actually two steps: electron transport along the inner mitochondrial membrane and the generation of ATP via ADP phosphorylation. protons are pumped from the mitochondrial matrix to the inner membrane space creating a proton motive force, an electrochemical proton gradient that is used to power oxidative phosphorylation. ATP synthase then uses this force to generate ATP by bringing them back into the matrix The ECT consist of 4 different complexes

What is fermentation and when does it occur?

when no oxygen is available fermentation is used to replenish NAD+ so that glycolysis can continue to create ATP - therefore it occurs in anaerobic conditions (such as in exercising muscles) or when the cells lack a mitochondria. In mammalian cells: Pyruvate --> Lactate + NAD+ In yeast cells: Pyruvate (3-C) --> Ethanol (2-C) + CO2 + NAD+