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APHY 102 Exam 1
Ch. 16 Endocrinology
| Question | Answer |
|---|---|
| what is the first great controlling system of the body? | the nervous system |
| what is the second great controlling system of the body? | the endocrine system |
| how does the the endocrine system control the body? | by influencing metabolic activities of cells by means of hormones |
| what are the 7 primary endocrine glands besides the gonads (ovary and testis)? | pituitary, thyroid, parathyroid, adrenal, pineal, pancreas, and thymus |
| what are some other tissues and organs that produce hormones? (recognize in multiple choice) | adipose cells, pockets of cells in small intestine walls, stomach, kidneys, heart |
| true or false, the pancreas and gonads produce both hormones and exocrine products? | true |
| what are the exocrine products of the pancreas? | 1.5–2 liters daily of digestive juice containing sodium bicarbonate and enzymes (lipase, amylase, proteases) |
| what are the endocrine products of the pancreas? | insulin; glucagon |
| what are the exocrine products of the gonads? | sperm or eggs (ova) |
| what are the endocrine products of the gonads? | steroid hormones that govern reproduction, sexual development, and secondary sex characteristics. besides testosterone and estrogen, gonads also secrete peptide hormones like inhibin and activin to regulate gonadotropin release |
| overview: which endocrine gland also has neural functions? | the hypothalamus has both neural functions and releases hormones |
| simersong hint: what surrounds most of ventricle three in the brain? | hypothalamus |
| simersong hint: what is the center of the secretion of hormones for the pituitary? | hypothalamus |
| simersong hint: what is in charge of regulating temperature and sleep and the messages that keep your ANS functioning? | hypothalamus |
| simersong hint: what is prompting you to notice hunger and thirst? | hypothalamus |
| what are autocrine (chemicals)? | chemicals that exert effects on the same cells that secrete them |
| what are paracrine (chemicals)? | locally acting chemicals secreted into extracellular fluid (ECF) that are short-lived and affect nearby cells other than those that secrete them |
| why are autocrines and paracrines not considered hormones? | hormones travel through the bloodstream and are comparatively long-distance chemical signals |
| what are hormones? | chemical substances secreted by cells into the extracellular fluids (the bloodstream) |
| what are 3 characteristics of hormones? (recognize for multiple choice) | regulate the metabolic functions of other cells, have lag times ranging from seconds to hours, tend to have prolonged effects |
| what are the 3 classifications of hormones? | amino acid based hormones, steroids, eicosanoids |
| what are eicosanoids? | lipids that are biologically active and have local hormone-like activity |
| what categories of amino acid-based hormones are there? | amines, thyroxin(e), peptide, and protein hormones (these relatively don't last long!) |
| what categories of steroids are there? | gonadal and adrenocortical hormones (these are relatively long lasting!) |
| what categories of eicosanoids are there? | leukotrienes and prostaglandins |
| hormone action: what 2 mechanisms enable hormones to alter target cell activity? | second messengers and direct gene activation |
| on what does the response of second messengers or direct gene activation depend? | depends on the type of the target cell being stimulated (thus allowing for specificity) |
| how are second messengers characterized? | involve regulatory G proteins and are amino acid-based hormones--CANNOT enter the cell |
| how are direct gene activation hormones characterized? | these are steroid hormones that DO enter the cell |
| what 5 effects can hormone mechanisms produce? | altering plasma membrane permeability, stimulate protein synthesis, activate or deactivate enzyme systems, induce secretory activity, stimulate mitosis (PMAT) |
| what is the 5-step process for second messengers? (1) | 1. ligand chemical/hormone is a first messenger that binds to its receptor |
| what is the 5-step process for second messengers? (2) | 2. G protein, activated, binds GTP and displaces GDP |
| what is the 5-step process for second messengers? (3) | 3. activated G protein activates effector enzyme adenylate cyclase |
| what is the 5-step process for second messengers? (4) | 4. adenylate cyclase generates cAMP (second messenger) from ATP |
| what is the 5-step process for second messengers? (5) | 5. cAMP activates protein kinases, which then cause cellular effects |
| which hormones act by way of the second messenger system? | catecholamines, ACTH (adrenocorticotropic), FSH (follicle stimulating), LH (luteinizing), glucagon, PTH (parathyroid), TSH (thyroid stimulating), calcitonin |
| what are catecholamines? | neurohormones produced by the adrenal glands and nervous system—primarily dopamine, norepinephrine (noradrenaline), and epinephrine (adrenaline)—that function as neurotransmitters and hormones |
| note for true or false: more than one hormone may have receptors in the same cell's membrane, so that that cell could respond to either hormone | true |
| what types of responses are triggered in the target cell by the second messenger system? | enzyme activation, cellular secretion stimulation, ion channels opening, etc. |
| how are peptide hormones and catecholamines (like insulin and epinephrine) different from lipid-soluble (lipophilic) hormones? | bind to receptors on the surface of cell membranes because they are hydrophilic (water-soluble) |
| enzyme amplification true or false: a single hormone molecule can lead to billions of molecules of second messengers | true |
| what are the key aspects of the PIP2-calcium signaling pathway? (1) | hormone binds to the receptor and activates G protein |
| what are the key aspects of the PIP2-calcium signaling pathway? (2) | G protein binds and activates phospholipase |
| what are the key aspects of the PIP2-calcium signaling pathway? (3) | phospholipase splits the phospholipid PIP2 into diacylglycerol (DAG) and IP3 (both act as 2nd messengers) |
| what are the key aspects of the PIP2-calcium signaling pathway? (4) | DAG activates protein kinases; IP3 triggers release of Ca2+ stores |
| what are the key aspects of the PIP2-calcium signaling pathway? (5) | Ca2+ (third messenger) alters cellular responses |
| what type of cellular responses is the PIP2-calcium signaling pathway associated with? | smooth muscle contraction, exocytosis (secretion), neuronal signaling, and cell proliferation |
| which amino acid-based hormones use the PIP mechanism? | catecholamines, TRH (thyrotropin-releasing), ADH (anti-diuretic), GnRH (gonadotropin-releasing) |
| from what are steroid hormones synthesized? | cholesterol |
| how many rings does a steroid backbone have chemically? | the steroid backbone of a hormone is a 4-ringed steroid backbone, to which functional groups attach |
| how do steroid hormones function? | prompt DNA transcription to produce mRNA. the mRNA is translated into proteins, which bring about a cellular effect |
| which hormones have their effects using mRNA/protein translation? | steroids and thyroid hormone(!) |
| what should I know off the bat about target cell specificity? | hormones circulate to all tissues but only activate cells referred to as target cells |
| what is the requirement for target cells to react to hormones? | they must have specific receptors to which the hormone binds |
| where will the receptors of target cells be? | they may be intracellular (in the case of steroids or thyroid hormones) or located on the plasma membrane for amino acid-based hormones, peptides, or catecholamines |
| what are some examples of target cell specificity? | ACTH receptors are only found on certain cells of the adrenal cortex; thyroxin(e) (thryoid hormone) receptors are found in nearly all cells of the body |
| what 3 factors influence target cell activation? | blood levels of the hormone, relative number of receptors on the target cell, the affinity(!) of those receptors for the hormone |
| what is up-regulation? | target cells form more receptors in response to the hormone |
| what is down-regulation? | target cells lose receptors in response to the hormone |
| for which process will cells become insensitive to a hormone when you take very high pharmacological doses? | down-regulation |
| what are the 2 forms in which hormones circulate in the blood? (know examples) | free (amino acid-based are free) or bound (steroids and thyroid hormone are attached to plasma proteins) |
| explain what it means to be a bound hormone? | hydrophobic hormones such as steroids and thyroid hormone are soluble in fats and can therefore dissolve in the plasma membrane to enter the cell. they are afraid of water and need a plasma protein while they're traveling in the watery blood |
| what method of stimulation do bound hormones use? | intracellular method of stimulation |
| what are intracellular methods of stimulation? | directly manipulating the interior of a cell to trigger responses, bypassing the cell membrane |
| what characterizes hydrophilic hormones such as amino-acid based hormones? | these travel free in the blood plasma but can't dissolve in lipid, so they have to stay outside the cell and use the second-messenger system of stimulation |
| true or false, hydrophoic hormones (steroids and thryoid hormones) aka bound hormones - enter the nucleus and needed transport proteins in the blood | true |
| true or false, hydrophilic hormones such as catecholamines and peptides are free and did not need transport proteins in the blood | true |
| how are hormones removed from the blood? | degrading enzymes, kidney filtration, or liver enzyme systems |
| what 2 things are reflected by concentrations of circulating hormone? | rate of release; speed of inactivation and removal from the body |
| what are the 3 types of hormone interactions at target cells? | permissiveness, synergism, and antagonism |
| what is permissiveness? | one hormone cannot exert its effects without another hormone being present: it needs permission to do its job |
| what is synergism? | more than one hormone produces the same effects on a target cell: they work together |
| what is antagonism? | one or more hormones opposes the action of another hormone: ex) insulin vs. glucagon |
| what controls blood levels of hormones, positive or negative feedback systems? | negative feedback systems, and vary only within a narrow desirable range |
| what 3 stimuli categories are hormones synthesized and released in response to? | humoral, neural, and hormonal stimuli (so yes - hormones can trigger other hormones!) |
| what are humoral stimuli? | secretion of hormones in direct response to changing blood levels of ions and nutrients (such as calcium ions in the blood) |
| can you illustrate the concentration of calcium ions int he blood? | declining blood Ca2+ concentration stimulates the parathyroid glands to secrete PTH (parathyroid hormone); PTH causes Ca2+ concentrations to rise and the stimulus is removed |
| what are neural stimuli? | when nerve fibers stimulate hormone release ex) preganglionic sympathetic nervous system fibers stimulate the adrenal medulla to secrete catecholamines |
| what are hormonal stimuli? | when there is a release of hormones in response to other endocrine organs producing hormones |
| what are some examples of hormonal stimuli? | the hypothalamic hormones stimulate the anterior pituitary, and in turn, pituitary hormones stimulate other target organs to secrete still more hormones |
| know the thryoid-related hormones pathway (1) | start at the hypothalamus which releases TRH (thyrotropin-releasing hormone) |
| know the thryoid-related hormones pathway (2) | TRH travels through the hypothalamo-hypophyseal portal system to the anterior pituitary gland (adenohypophysis) and stimulates it to release thyroid-stimulating hormone aka TSH or thyrotropin (notice R comes before S in alphabet) |
| know the thryoid-related hormones pathway (3) | TSH then travels in the blood vascular system to the thyroid gland and stimulates it to release thyroid hormone (aka T3 and T4) |
| be sure to recognize which is T3 and which is T4 | T3 is triiodothyronine and T4 is tetraiodothyronine; T4 alone is also called thyroxin(e) |
| example of negative feedback from target organs to pituitary | target organ hormone levels inhibits release of tropic hormones |
| how does the nervous system modify the stimulation of endocrine glands and their negative feedback mechanisms? | adjusts the set points of negative feedback loops |
| true or false: the nervous system can override normal endocrine controls | true |
| what is an example of the nervous system overriding endocrine controls? | blood glucose levels, normally maintained by the endocrine system, may under stress need to increase, so the hypothalamus and sympathetic nervous system are activated to supply ample glucose |
| what is the technical term for the pituitary? | hypophysis |
| how many lobes does the pituitary gland have? | 2 |
| how many major hormones does the pituitary gland secrete? | 9 |
| what are the 9 major hormones of the pituitary gland? | anterior lobe produces seven hormones—GH, PRL, ACTH, TSH, FSH, LH, and MSH—while the posterior lobe stores and releases two, ADH and oxytocin, which are produced by the hypothalamus |
| what is the technical name for the posterior lobe of the pituitary gland and what comprises it? | neurohypophysis is neural tissue with the infundibulum (pituitary stalk) |
| what is the function of the neurohypophysis? | receives, stores, and releases hormones from the hypothalamus but does NOT synthesize these hormones |
| what is the adenohypophysis? | anterior lobe of the pituitary gland, made up of glandular tissue and is vascular. synthesizes and secretes a number of hormones |
| true or false, the pituitary and hypothalamus have nothing to do with each other | false |
| what is the anatomical relationship of the posterior lobe of the pituitary to the hypothalamus? | the posterior lobe (neurohypophysis) is a downgrowth of hypothalamic neural tissue so has a neural connection with the hypothalamus called the hypothalamic-hypophyseal tract (collection of axons in the CNS) |
| how does the neurohypophysis get its hormones, i.e., from where? | nuclei (collection of cell bodies of the CNS) of the hypothalamus synthesize oxytocin and ADH (antidiuretic hormone). these are transported to the posterior pituitary (neurohypophysis) for storage and later release |
| what is the anatomy of the anterior lobe of the pituitary? | aka the adenohypophysis, this is an outpocketing of the oral mucosa. there is NO direct neural contact with the hypothalamus |
| true or false, the hypothalamic-hypophyseal tract and the hypophyseal portal system are the same thing | false |
| what is the hypophyseal portal system? | a vascular connection consisting of the primary capillary plexus around the hypothalamus, the hypophyseal portal veins, and the secondary capillary plexus around the adenohypophysis |
| what are the 6 hormones of the adenohypophysis? | GH, TSH, ACTH, FSH, LH, PRL and these regulate the activity of other endocrine glands |
| note about another adenohypophyseal hormone called POMC | pro-opiomelanocortin has been isolated from the anterior pituitary and is split into ACTH, opiates, and MSH |
| note about MSH | melanocyte-stimulating hormone plays a role in the pigmentation of animal skin, fur and feathers but does NOT serve this function in humans |
| true or false, MSH does have a role in appetite control in humans | true |
| what is the activity of the adenohypophysis? | the hypothalamus sends a chemical stimulus to the anterior pituitary; releasing hormones stimulate the synthesis and release of hormones; inhibiting hormones shut off the synthesis and release of hormones |
| what are the tropic hormones released at the adenohypophysis? | GH, TSH, ACTH, FSH, LH |
| what produces GH (growth hormone)? | produced by somatotropic cells aka somatotropes of the anterior lobe that stimulate most cells, but target bone and skeletal muscle, and promote protein synthesis and encourage the use of fats for fuel |
| what mediates the effects of GH? | somatomedins mediate GH effects indirectly: they indirectly stimulate the liver to produce IGF-I & -II somatomedins |
| what is IGF? | insulin-like growth factor, has a half-life of 20 hours compared to 20 minutes for GH, so, IGFs prolong GH's effect |
| what REGULATES growth hormone? | antagonistic hypothalamic hormones regulate GH: GHRH stimulates GH release, and GHIH aka somatostatin inhibits GH release |
| what is the metabolic action of growth hormone? (1) | GH stimulates liver, skeletal muscle, bone, and cartilage to produce IGFs (insulin-like growth factors) |
| what is the metabolic action of growth hormone? (2) | direct action of GH promotes lipolysis for energy and inhibits glucose uptake (glucose-sparing): mimics high glucose blood levels of diabetes, hence the term diabetogenic effect |
| what does TSH do? | thyroid stimulating hormone, released by the adenohypophysis, stimulates the normal development and secretory activity of the thyroid gland |
| what triggers TSH intitially? | triggered by the hypothalamic peptide TRH (thyrotropin releasing hormone) |
| what stops TSH? | rising blood levels of thyroid hormones act on the pituitary and hypothalamus to block the release of TSH (negative feedback effect!) |
| what does adrenocorticotropic hormone (aka corticotropin) do? | stimulates the adrenal cortex to release corticosteroids |
| what triggers corticotropin? | triggered by hypothalamic corticotropin-releasing hormone (CRH) in a daily rhythm |
| what other factors trigger release of CRH? | internal and external factors such as fever, hypoglycemia, and stressors can trigger the release of CRH |
| what are gonadotropins? | essential glycoprotein hormones produced by the pituitary gland that regulate growth, sexual development, and reproduction by acting on the gonads (testes and ovaries); controlled by GnRH from the hypothalamus |
| which gonadotropins are important to know? | follicle-stimulating hormone--FSH--and luteinizing hormone--LH |
| what do gonadotropins do? | regulate the function of the ovaries and testes |
| what triggers gonadotropins? | the hypothalamic gonadotropin-releasing hormone (GnRH) during and after puberty |
| what does FSH do? | stimulates gamete (egg or sperm) production |
| true or false, prepubertal boys and girls have gonadotropins in their blood | false |
| in females, how exactly do gonadotropins function? | LH works with FSH to cause maturation of the ovarian follicle; LH works alone to trigger ovulation, and LH promotes synthesis and release of estrogens and progesterone(!) |
| what is ovulation? | expulsion of the egg from the follicle in a female |
| in males, how do gonadotropins function? | LH, aka ICSH (interstitial cell-stimulating hormone), stimulates interstitial cells of the testes to produce testosterone |
| what does prolactin do? | in females, stimulates milk production by the breasts |
| what triggers PRL? | prolactin is triggered by the hypothalamic prolactin-releasing hormone PRH |
| what inhibits PRL? | prolactin is inhibited by PIH which is dopamine(!) |
| blood levels of PRL rise when in females? | toward end of pregnancy: suckling stimulates PRH release (thereby stimulating PRL) and encourages continued milk production |
| what is the anatomy of the posterior pituitary? (neurohypophysis) | made of axons of hypothalamic neurons |
| what is the physiology of the posterior pituitary? | stores antidiuretic hormone (ADH) and oxytocin |
| where are ADH and oxytocin synthesized? | in the hypothalamus, not the neurohypophysis itself |
| what does ADH influence? | water balance |
| what does oxytocin stimulate? | smooth muscle contraction in breasts and uterus |
| true or false: both ADH and oxytocin use PIP-calcium second-messenger mechanism | true |
| what is a oxytocin a strong stimulant of in females? | uterine contraction |
| what regulates oxytocin? | a positive feedback mechanism to oxytocin in the blood, leading to increased intensity of uterine contractions and ending in birth |
| what is the main difference in function between oxytocin and prolactin? | prolactin is related to milk production while oxytocin triggers milk ejection ("letdown" reflex) |
| true or false: synthetic and natural oxytocic drugs are used to induce or hasten labor | true |
| what other role does oxytocin play in non-lactating people? | sexual arousal and satisfaction |
| what is the role of ADH (antidiuretic hormone)? | helps to avoid dehydration or water overload |
| how does ADH work? | stimulates aquaporin installation in the collecting duct to allow water reabsorption from urine. concentrates urine |
| relating to ADH, what monitors the solute concentration of the blood? | osmoreceptors |
| when blood solutes are high, what does ADH do? | preserves water |
| when blood solutes are low, what happens to ADH? | it is not released, thus causing water loss (urine release) |
| what is alcohol's effect on ADH release? | inhibits ADH release and causes copious urine output |
| what is the largest endocrine gland? | thyroid |
| where is the thyroid and what is its anatomy (Fig. 15.8)? | the largest endocrine gland, the thyroid, is located in the anterior neck, consisting of two lateral lobes that are connected by a median tissue mass called the isthmus. the thyroid is composed of follicles that produce the glycoprotein thyroglobulin |
| what should I know about thryoid hormones production? | colloid (thyroglubulin + iodine) fills the lumen of the follicles in the thyroid and is the precursor of thyroid hormone(s). other endocrine cells, the parafollicular cells, produce calcitonin (tones down blood calcium levels) |
| what is the major metabolic hormone of the thyroid? | thyroid hormone, which consists of two related iodine-containing compounds--T4 and T3 |
| what is T4? | also known as thyroxin(e) or tetraiodothyronine, it has two tyrosine molecules plus four bound iodine atoms, makes up NINETY percent of thyroid hormone secreted |
| what is T3? | also known as triiodothyronine, it has two tyrosines with three bound iodine atoms, make up just TEN percent of thyroid hormone secreted |
| between T3 and T4, which is the most active form of thyroid hormone? | triiodothyronine (T3) is the most active form of thyroid hormone. while the thyroid gland produces some T3, most is created by converting inactive thyroxine (T4) into T3 within tissues |
| what are the 3 primary roles of TH? | glucose oxidation, increasing metabolic rate, heat production--aka the calorigenic effect |
| what else does TH play a role in? (four things) | maintaining blood pressure, regulating tissue growth, developing skeletal and nervous systems, maturation and reproductive capabilities |
| how is TH synthesized? (1) | thyroglubulin is synthesized and discharged into the thyroid lumen, iodides (I-) are actively taken into the cells, oxidized to iodine (I2) and released into thte lumen |
| how is TH synthesized? (2) | iodine attached to tyrosine, mediated by peroxidase enzymes, forming T1 (monoiodotyrosine, or MIT), and T2 (diiodotyrosine, or DIT) |
| (highlighted) how is TH synthesized? (3) | iodinated tyrosines link together to form T3 and T4 |
| how is TH synthesized? (4) | colloid is then endocytosed and combined with a lysosome, where T3 and T4 are cleaved and diffuse into the bloodstream |
| remember that TH is hydrophobic and needs an escort in the blood. so what do T4 and T3 bind to? | thyroxine-binding globulins or TBGs produced by the liver |
| both T3 and T4 bind to target receptors. which is 10xs more active than the other? | T3 is ten times more active than T4 due to affinity to cells and T4 being more of a prohormone/storage form |
| true or false: peripheral tissues usually convert T3 to T4 | false, it's T4 to T3 |
| mechanisms of activity for TH are similar to what? | steroids |
| how is TH regulated? | negative feedback |
| what does it mean that hypothalamic TRH (thyrotropin-releasing hormone) can overcome the TH negative feedback loop? | the brain urges the hypothalamus to signal for increased metabolic activity when the body needs more heat or energy, regardless of standard homeostasis |
| rememer that TH acts as a steroid so it binds to receptors on mitochondria. one of the proteins produced is what pump? | the sodium-potassium pump or Na+-K+ ATPase which generates heat |
| what is endemic goiter? | a widespread enlargement of the thyroid gland caused by chronic dietary iodine deficiency... thyroid gland hypertrophies |
| why does endemic goiter occur? | body can't make TH without dietary iodine, so no negative feedback occurs, secreting more and more TRH and TSH, trying to make the thyroid gland to make TH |
| what type of hormone is calcitonin and what is it produced by? | peptide hormone produced by thyroidal parafollicular, or C cells, that lowers blood calcium levels in children |
| what are the antagonist hormones of calcitonin? | PTH (parathyroid hormone) and calcitriol (activated vitamin D) which raises blood calcium levels like PTH does |
| would calcitonin be hydrophobic or hydrophilic? would it act intracellularly or via second-messenger system? | calcitonin is a peptide, so it is hydrophilic and acts by a second-messenger system |
| what does calcitonin target and what does it do there? | targets the skeleton. it inhibits osteoclast activity (thus inhibiting bone resorption) and release of calcium from the bone matrix |
| which hormone stimulates calcium uptake and incorporation into the bone matrix? | calcitonin |
| what type of interaction/feedback mechanism is calcitonin regulated by? | a humoral negative feedback mechanism (calcium ion concentration in the blood) |
| where/what are the parathyroid glands? | tiny glands embedded in the posterior aspect of the thyroid where cells are arranged in cords containing oxyphil and chief cells that secrete PTH |
| what is the other name of PTH? what does PTH do? | parathyroid hormone is also known as parathormone, and it regulates calcium balance in the blood |
| what are the effects of PTH? | release of PTH increases Ca2+ in the blood |
| how does PTH increase Ca2+ in the blood? | stimulates osteoclasts to digest bone matrix and enhances the reabsorption of Ca2+ and the EXCRETION of phosphate by the kidneys; also increases absorption of Ca2+ by intestinal mucosal |
| how would excreting phosphate ions help PTH increase Ca2+ in the blood? | less phosphate in the blood decreases the rate of crystallization of calcium ions into bone (calcium phosphate) |
| where/what are the adrenal glands? and describe a facet of their anatomy and physiology. | paired, pyramid-shaped organs atop the kidneys--structurally and functionally, they are two glands in one |
| what are the two glands that make up an adrenal gland? | adrenal medulla and adrenal cortex. adrenal medulla is neural tissue acting as sympathetic nervous system, and the cortex is glandular tissue derived from embryonic mesoderm |
| what hormone class is the adrenal cortex responsible for? | the adrenal cortex synthesizes and releases steroid hormones called corticosteroids |
| what are the three subclasses of corticosteroids? | mineralocorticoids, glucocorticoids, gonadocorticoids |
| which corticosteroids are produced in each of the 3 layers of the adrenal cortex? (GFR from superficial to deep) | zona glomerulosa = mineralocorticoids--chiefly aldosterone, zona fasciculata = glucocorticoids--chiefly cortisol, zona reticularis = gonadocorticoids--chiefly androgens |
| what is the role of mineralocorticoids? | regulate electrolytes in extracellular fluids |
| what is the most important mineralocorticoid? | aldosterone |
| what are the characteristics of aldosterone? | maintains Na+ balance by reducing excretion of sodium from the body, stimulates reabsorption of Na+ by the kidneys, aka the "salt-retaining hormone" |
| what stimulates aldosterone secretion? | rising blood levels of potassium (K+), low blood Na+, and/or decreasing blood volume or pressure |
| how does aldosterone help counteract decreasing blood volume or pressure? | wherever sodium goes, water is sure to follow! aldosterone signals the kidneys to retain sodium and water, increasing total blood volume at the distal convoluted tubule in the kidney |
| what are the 4 mechanisms of aldosterone secretion (Fig. 15.14)? | renin-angiotensin mechanism, plasma concentration of sodium and potassium directly influence zona glomerulosa, ACTH causes small increases during stress, and ANP (atrial natriuretic peptide) inhibits zona glomerulosa |
| what is the renin-angiotensin mechanism? | kidneys release renin, which converts angiotensinogen into angiotensin II that in turn stimulates aldosterone release |
| what does the glucocorticoid, cortisol, do? | helps the body resist stress by keeping blood sugar levels relatively constant; maintains blood volume and prevents water from shifting into tissue |
| what else? what does cortisol provoke? | cortisol provokes gluconeogenesis (formation of glucose from noncarbohydrates); cortisol also provokes rises in blood glucose, fatty acids, and amino acids |
| what are 4 results of excessive glucocorticoids/cortisol? | depress cartilage and bone formation; inhibit inflammation; depress immune system; promote changes in cardiovascular, neural, and gastrointestinal function |
| what class are most gonadocorticoids secreted by the adrenal cortex in the zona reticularis? | androgens (male sex hormones)--chiefly, DHEA that gets made into testosterone, with small amounts of female hormones/estrogens also |
| true or false, gonadocorticoids secreted by the adrenal cortex compare almost the same to amounts secreted by the gonads | false, they are almost insignificant |
| androgens contribute to what 3 things? | onset of puberty, appearance of secondary sex characteristics like axillary and pubic hair, sex drive in females |
| true or false, androgens can be converted into estrogens in limited quantities after menopause | true |
| deep to the zona reticularis is the adrenal medulla. what cells are in the adrenal medulla and what do they secrete? | chromaffin cells that secrete epinephrine and norepinephrine, aka adrenaline and noradrenaline |
| secretion of the catecholamines (epinephrines) results in what? | sympathetic response/flight or fight response such as rising blood glucose, constricting blood vessels, faster heartbeat, blood to brain, heart and muscles |
| epinephrine and norepinephrine have similar effects but differ how? | epinephrine is more potent stimulator of the heart and metabolic activities, norepinephrine influences more peripheral vasoconstriction and blood pressure |
| what is the acronym GAS relative to the stress response? | general adaptation syndrome |
| define stress? | any situation that upsets homeostasis and threatens one's physical or emotional well-being |
| the stress response or GAS involves elevated levels of what hormones? | epinephrine and glucocorticoids (cortisol) |
| what are Hans Selye's 3 stages to GAS? | alarm reaction, stage of resistance, stage of exhaustion |
| what happens during the GAS alarm reaction? | norepinephrine and epinephrine prepare body for fight-or-flight. depletes glycogen |
| what happens during the GAS stage of resistance? | hours later, cortisol is secreted to break down fat and protein for gluconeogenesis. protein synthesis inhibited--as is the immune system. increased sickness chance! also, glucose made is spared for glucose-dependent brain |
| what happens during the GAS stage of exhaustion? | months later, fat is depleted. wasting of muscles. rapid decline and death |
| what is the pancreas? | a triangular gland, having both exocrine and endocrine cells, located behind the stomach (Left Upper Quadrant) |
| what is the exocrine product of the pancrease? | acinar cells produce an enzyme-rich juice used for digestion |
| what are the endocrine products of the pancreas? | islets of Langerhands produce hormones--ALL GUYS BUY ICE CREAM mnemonic--alpha cells produce glucagon, beta cells produce insulin |
| describe glucagon | a 29-amino-acid polypeptide hormone that is a potent hyperglycemic agent (sugar in bloodstream) |
| what is the major target of glucagon? | the liver |
| what 3 processes does glucagon promote at the liver? | glucogenolysis (breakdown of glycogen to glucose), gluconeogenesis (synthesis of glucose from lactic acid and noncarbohydrates), and release of glucose to the blood from liver cells |
| describe insulin | a 51-amino-acid protein consisting of two amino acid chains linked by disulfide bonds, synthesized as part of proinsulin and then excised by enzymes, releasing functional insulin |
| what are the 3 functions of insulin? | lowers blood glucose levels, enhances transport of glucose into body cells, counters metabolic activity that would enhance blood glucose cells |
| regarding insulin binding: what is the receptor of insulin? | an enzyme named tyrosine kinase |
| after glucose enters a cell, insulin binding triggers enzymatic binding that does what 3 things? | catalyzes the oxidation of glucose for ATP production, polymerizes glucose to form glycogen, converts glucose to fat (particularly in adipose tissue) |
| what are the 3 cardinal signs of diabetes mellitus (DM)? | polyuria, polydipsia, polyphagia (excessive urine, thirst, and eating) |
| what causes diabetes mellitus? | Type I with juvenile onset comes from hyposecretion of insulin and Type II with adult onset comes from hypoactivity of insulin |
| why does diabetes mellitus cause polyuria? | high blood glucose levels (hyperglycemia) overwhelm the kidneys' ability to reabsorb sugar. the excess glucose is excreted in the urine, dragging large amounts of water with it |
| why does diabetes mellitus cause excessive thirst (polydipsia)? | increased urination (polyuria) triggers the body's thirst mechanism to replenish fluid loss |
| why does diabetes mellitus cause excessive hunger (polyphagia)? | glucose cannot enter cells to be used for fuel, triggering the brain to signal constant hunger |
| what is hyperinsulinism and what does it result in? | hyperinsulinism is excessive insulin secretion (or overdose), resulting in hypoglycemia, most affecting the brain, fixed by ingesting sugar |
| why does diabetes mellitus cause soft eyeballs? | fluctuating blood sugar levels (hyperglycemia) damages eye structures, causes fluid imbalances, and impairs nerve function |
| why does diabetes mellitus cause hyperpnea (Kussmaul respiration)? | Deep, rapid breathing is a compensatory mechanism to combat severe metabolic acidosis |
| what are the female gonads? | paired ovaries in the abdominopelvic cavity produce estrogens and progesterone |
| what 3 developments in the human bodies are ovaries responsible for? | female maturation of the reproductive organs, appearance of secondary sexual characteristics, breast development and cyclic changes in the uterine mucosa |
| what are the male gonads? | testes located in an extra-abdominal sac (scrotum) produce testosterone |
| what 4 functions does testosterone have? | initiates maturation of male reproductive organs, causes appearance of secondary sexual characteristics and sex drive, is necessary for sperm production, maintains sex organs in their functional state |
| what is the pineal gland's anatomy? | small gland hanging from the roof of the third ventricle of the brain |
| what does the pineal gland secrete? | melatonin |
| what 2 points is melatonin involved with? | day/night cycles (circadian rhythm), physiological processes that show rhythmic variations such as sleep, body temperature, appetite |
| what is the thymus' anatomy? | lobulated gland located deep to the sternum, atrophies by puberty |
| what two types of hormones secreted by the thymus are essential for the development of the T lymphocytes (T cells) of the immune system? | thymopoietins and thymosins |
| what 3 functions does the atrial natriuretic peptide (ANP) of the heart do? | reduce blood pressure, blood volume, and blood sodium concentration |
| what hormones does the GI tract release? | enteroendocrine cells release local-acting digestive hormones such as gastin, cholecystokinin, secretin, vasoactive intestinal peptide |
| what does the placenta release? | hormones that influence the course of pregnancy |
| what do the kidneys themselves release? | erythropoietin, which signals production of red blood cells |
| what does the skin release? | produces cholecalciferol, the precursor of vitamin D |
| what does adipose tissue release? | leptin, which signals satiety (the feeling of being full), and stimulates increased energy expenditure |
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elianayu
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