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60 Cards in this Set
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endocrine systems
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1.act with nervous system to coordinate and integrate the activity of body cells
2.influences metabolic activities by means of hormones transported in the blood 3.responses slowly but last longer than nervous system |
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Glands
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1. pineal
2. pituitary 3. thyroid 4. parathyroid 5. adrenal |
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organs: produce hormones and exocrine product
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1.pancreas
2.gonads |
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part of brain: neural and endocrine function
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hypothalamus
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tissue and organs: produce hormones
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1.adipose cell
2.thymus 3.cell in the wall of the small intestine 4.stomach 5.kidney 6.heart |
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3 chemical messengers
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1.hormones
2.autocrine 3.paracrine *autocrine and paracrine are local chemical messenger=not part of endocrine system |
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2 main class of hormones
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amino acid-based hormones
1.amines 2.thyroxine 3.peptides 4.proteins steroids 1.synthesized from cholesterol 2.gonadal 3.adrenocortical hormones |
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target cells must have specific receptors to which the hormone binds
Places of the receptors 1.ACTHreceptors 2.Thyroxin receptors |
1.ACTHreceptors
certain cell of the adrenal cortex 2.Thyroxin receptors all cell of the body |
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target cell activation depends on 3 factors
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1.blood levels of the hormone
2.relative number of receptors on or in the target cell 3.affinity of binding between receptor and horone |
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hormones influence the number of their receptors
2 regulations |
1.up-regulation
target cells form more receptors in response to the hormones 2.down regulation target cell lose receptors in response to the hormone |
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hormones circulate in the blood either free or bond
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[bond]
steroids hormone thyroid hormone [free] all others circulate without carries |
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the concentration of circulation hormone reflects
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1. rate of release
2. speed of inactivation and removal from the body |
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hormones are removed from the blood by
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1.degrading enzyme
2.kidneys 3.liver 4. half life- the time required for a hormone's blood level to decrease by half |
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3 ways of interaction by hormones
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1.permissiveness: one hormone cannot exert its effect without another hormone being present
2.synergism: more than one hormone produces the same effects on a target cell 3.antagonism: one or more hormones opposes the action of another hormone |
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control of hormone release
(blood levels of hormones) |
1.controlled by negative feedback system
2.vary only within a narrow desirable range |
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hormones are synthesized and release in response to
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1. humoral stimuli: changing blood levels of ion and nutrients directly stimulate secretion of hormone
2. neural stimuli: nerve fibers stimulate hormone release 3.hormonal stimuli: hormones stimulate other endocrine organs to release their hormones 1.hypothalamic Hstimulate the release of anterior pituitary H 2.anterior pituitary H stimulate targets to secrete more H 3.Hypothalamic-pituitary-target endocrine organ feedback loop: hormones from the final target organs inhibit the release of the anterior pituitary H |
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The nervous system modifies the stimulation of endocrine glands and their negative feedback mechanisms
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(ex) under sever stress, the hypothalamus and the sympathetic nervous system are activate
→glucose level ↑ |
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the pituitary gland (hypophysis) has two major lobes
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1.anterior pituitary lobe (adenohypophysis)
glandular tissue 2.posterior pituitary lobe pituicyte (glial-like supporting cells) nerve fibers |
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Anterior pituitary hormones
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1.Growth hormones (GH)
2.thyroid-stimulating H (TSH) or thyrotropin 3.adrenocorticotropic H (ACTH) 4.Follicle- stimulation H (FSH) =all proteins =All (except GH) activate cyclic AMP second messenger system at their targets =TSH, ACTH, FSH, LH= tropic hormones (regulate the secretory action of other endocrine glands) 5.Luteinzing hormone (LH) 6.Prolactin (PRL) |
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Growth Hormone (GH)
produced by somatotrophs (GH a.k.a. somatotropin) children (hypersecretion)→gigantism (hyposecretion)→pituitary dwarfism adult (hypersecretion)→acromegaly |
[stimulate] most cell
[target] bone and skeletal muscle to promote protein synthesis and encourages use of fats for fuel [effect] mediated indirectly by insulin-like growth factors (IGF5)(a somatomedin) [release is regulated by] ↑(GHRH) ↓(GHIH) (somatostain) [direct action of GH] stimulates liver, skeletal muscle, bone, and cartilage to produce insuline-like growth factors mobilizes fats, elevates blood glucose by decreasing glucose uptake and encourage glycogen breakdown (anti-insuline effect of GH) |
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thyroid-stimulating hormone (thyrotropin)
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[produce] by thyrotrophs of the anterior pituitary
[stimulate] the normal develop, and secretory activity of the thyroid [regulation of TSH release] [stimulate by] thyrotopin- releasing hormone (TRH) inhibited by rising blood levels of thyroid hormones that act on the pituitary and hypothalamus |
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hypothalamus →→TRH→→
anterior pituitary →→TSH→→ thyroid gland →→thyroid hormones→→ target cells |
thyroid hormones →→inhibit→→anterior pituitary
→→hypothalamus |
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Adrenocorticotropic hormone
(corticotropin) ACTH |
[secreted by] corticotrophs of the anterior pituitary
[stimulate] the adrenal cortex to releasecorticosteroids [regulation ] hypothalamic corticotropin releasing hormoone (GRH) in a daily rhythm fever, hypoglycemia, stressors can alter the release of CRH |
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gonadotrpins
Follicle- stimulating H (FSH) Luteinzing H (LH) |
[secreted by] gonadotrophs of the anterior pituitary
[stimulate] FSH→gamete (egg or sperm) LH→gonadal hormones *absent from the blood in prepubertal boy and girls [regulation of gonadtropin- release ] (Gonadotropin- releasing H (GnRH) during and after puberty -suppressed by gonadal H (feed back) |
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Prolactin (PRL)
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[secreted by ] lacototrops of the anterior pituitary
[stimulates] milk production [regulation of PRL release] *blood levels ↑ toward the end of pregnancy *suckling stimulates PRH release and promotes continued milk production -primarily controlled by prolactin inhibiting H (PIH) (dorpamine) |
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the posterior pituitary
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-contains axon of hypothalamic neurons
-store antidiuretic hormone (ADH) and oxytocin -ADH and oxytocin are released in response to nerve impulses -both use PIP-calcium second messenger mechanism at there target |
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Oxytocin
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stimulates urterine contractions during childbith by moblizing Ca2+ though a PIP2-Ca2+ second messenger system
-triggers milk ejection ("letdown" reflex) in women producing milk -play a role in sexual arousal and orgasm in male and females |
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Antidiuretic hormone (ADH)
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-hypothalamic osmorecepors respond to changes in the solute concentration of the blood
-if solute concentration is high --osmoreceptors depolarize and transmit impulses to hypothalamic neurons --ADH is synthesized and released, inhibiting urine formation -if solute concentration is low --ADH is not released, allowing water loss -Alcohol inhibits ADH release and causes copious urine output -ADH deficiency- diabetes insipidus; huge output of urine and intense thirst -ADH hypersecretion (after neurosurgery, trauma, or secreated by cancer cells) - syndrome of inappropriate ADH secretion (SIADH) |
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thyroid gland
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-the isthmus--consists of two lateral lobes connected by a median mass
-composed of follicles that produce the glycoprotein thyroglobulin -colloid (thyroglobulin + iodine) fills the lumen of the follicles and is the precursor of thyroid hormone -parafollicular cells produce the hormone calcitonin |
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thyroid hormone (TH)
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[2 compounds]
T4 (thyroxine): 2 tyrosine molecules+4bound iodine atoms T3 (triiodothyronine): 2 tyrosines + 3 bound iodine atoms -major metabolic hormone -↑metabolic rate & heart production (calorigenic effect) [play a role in] -maintenance of blood pressure -regulation of tissue growth -development of skeletal & nervous systems -reproductive capabilities |
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calcitonin
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[produced by] parafollicular (c) cell at thyroid
-antagonist to parathyroid hormone (PTH) -inhibits osteoclast activity and release of Ca2+ from bone matrix -stimulates Ca2+ uptake and incorporation into bone matrix -regulated by a humoral (Ca2+ concentration in the blood) negative feedback mechanism *no important role in humans; removal of thyroid (and its C cells) does not affect Ca2+ homeostasis |
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parathyroid glands
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-4 to 8 tiny glands embedded in the posterior aspect of the thyroid
-contain oxyphil cells (function unknown) and chief cells that secrete parathyroid hormone (PTH) or parapthormone -PTH functions 1.stimulate osteoclasts to digest bone matrix 2.enhances reabsorption of Ca2+ and secretion of phosphate by the kidney. 3.promotes activation of vitamin D (by the kedneys): ↑absorption of Ca2+ by intestinal mucosa *negative feedback control: rosomg Ca2+ in the blood inhibits PTH release |
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Homeostatic imbalances of PTH
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-hyperparathyroidism due to tumor
--bones soften and deform --elevate Ca2+ depress the nervous system and contribute to formation of kidney stone -hypoparathyroidism following gland trauma or removal ==tetany, respiratory, paralysis, and death |
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Adrenal (suprarenal) glands
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-paired, pyramid-shaped organs atop the kidneys
-structurally and functionally, they are tow glands in one --Adrenal medulla: nervous tissue; part of the sympathetic nervous system --Adrenal cortex- 3 layers of glandular tissue that synthesize and secrete corticosteroids 3 layers and corticosteroids produced -zona glomerulosa- mineralocorticoids -zona fasciculata- glucocorticoids -zona reticularis- sez hormones, or gonadocorticoids |
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mineralocorticoids
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-regulate electrolyte (primarily Na+ and K+ mineral salt) in excellular fluids
-importantce of Na+: affects ECF volume, blood volume, blood pressure, level of other ions [Aldsterone]- most potent mineralocorticoid --stimulates Na+ reabsorption andwater retention by the kedney [Aldosteronism] hypersecretion due to adrenal tumors --hypertension and edema due to excessive Na+ --Excretion of K+ leading to abnormal function of neurons and muscle -importance of K+: sets resting membrane potential of cell |
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Glucocorticoids (cortisol)
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-keep blood sugar levels relatively constant
-maintain blood pressure by ↑ the action of vasoconstrictors [cortisol] most significant glucocorticoid -released in response to ACTH, patterns of eating and activity and stress -prime metabolic effect is gluconeogenesis- formation of glucose from fats and proteins -promotes ↑ in blood glucose, fatty acids and amino acids |
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homeostatic imbalance of glucocorticoids
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★hypersecretion- cushing's syndrome
-depresses cartilage and bone formation -inhibits inflammation -depresses the immune system -promotes changes in cardiovascular, neural, and gastrointestinal function ★hyposecretion- addison's disease -also involves deficits in mineralocorticoids --↓ in glucose and Na+ levels --weight loss, severe dehydration and hypotension |
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gonadocorticoids (sex hormones)
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-most are androgen( male sex hormones) that are converted to testosterone in tissue cells or estrogen in female
-may contribute to --the onset of puberty --the appearance of secondary sex characteristics --sex drive |
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adrenal medulla
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-chromaffin cells secrete epinephrine (80%) and norepinephrine (20%)
-cause --blood glucose levels ↑ --blood vessels to constrict --the heart to beat ↑ --blood to be diverted to the brain, heart, and skeletal muscle [hormones] -Epinephrine stimulate metabolic activities, bronchial dilation, and blood flow to skeletal muscles and the heart -Norepinephrine influences peripheral vasoconstriction and blood pressure |
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short-term stress response (adrenal gland)
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1.Hypothalamus →
2.nerve impulses → 3.spinal cord → 4.preganglionic sympathetic fibers → 5.andrenal medulla (secretes amino acid- based hormones)→ 6.catecholamines (epinephrine and norepinephrine) [results] 1.↑ heat rate 2.↑ blood pressure 3. [LIVER] glycogen →glucose →blood 4.dilation of bronchioles 5. changes in blood flow patterns → ↓ digestive system activity & ↓urine output 6. ↑ metabolic rate |
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More prolonged stress (adrenal gland)
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1.hypothalamus →
2. CRH (corticotropin- relesing H)→ 3.corticotroph cells of anterior pituitary → 4.ACTH (to target in blood) → 5.adrenal cortex (secretes steroid hormones) → 6.mineralocorticoids OR 6.Glucocorticoids [mineralocorticoids] 1.retention of Na+ and water by kideny 2.↑blood volume & blood pressure [Glucocorticoids] 1.proteins and fat →glucose or brake down for energy 2. ↑blood glucose 3.suppression of immune system × |
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Pineal gland
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-small bland hanging from the roof o the third ventricle
-pinealocyte secrete melatonin, derived from serotonin [melatonin may affect] -timing of sexual maturation and puberty -day/ night cycle -physiologica processes that show rhythmic variations (body temperature, sleep, appetite) |
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Pancreas
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-triangular gland behind the stomach
-has both exocrine and endocrine cells -Acinar cell (exocrine) produce and enzyme-rich juice for digestion -pancreatic islets (islets of langerhans) contain endocrine cell [pancreatic islets ] -alpha cell: produce glucagon (hyperglycemic H) --major target is the liver, where it promotes --glycogenolysis: breakdown of glycogen → glucose --gluconeogenesis: synthesis of glucose from lactic acid & noncarbohydrates --release of glucose to the blood -Beta cell: produce insulin (hypoglycemic H) |
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insulin
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[effects]
- lowers blood glucose level -enhance membrane transport of glucose into fat and muscle cells -participates in neuronal development & leaning & memory -inhibits glycogenolysis & gluconeogenesis [action on cells] -activates a tyrosine kinase enzyme receptor - cascade leads to ↓ glucose uptake and enzymatic actives that --catalyze the oxidation of glucose for ATP production --polymerize glucose to form glycogen --convert glucose→fat (particularly in adipose tissue) |
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homeostatic imbalances of insulin
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[Diabetes mellitus (DM)]
--due to hyposecretion or hypoactivity of insulin --3 cardinal signs of DM 1.polyuria: huge urine output 2.polydipsia: excessive tirst 3.polyphagia- excessive hunger & food consumpiton [hyperinsulinism] excessive insulin secretion; result in hypoglycemia disorientation, unconsciouness |
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Ovaries 卵巣
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-gonads(生殖腺) produce steroid sex hormones
-ovaries produce estrogen and progesterone for 1.maturation of female secondary sexual characteristics 2.appearance of female secondary sexual characteristics 3.breast development and cyclic changes in the uterine mucosa |
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placenta
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secretes estrogen, progesterone & human chorionic gonadotropin (hCG)
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testes
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produce testosterone that
1.initiates maturation of male reproductive organs 2.causes appearance of male secondary sexual characteristics and sex drive 3.in necessary for normal sperm production 4.maintains reproductive organs in their functional state |
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Heart
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atrial natriuretic peptide (ANP)
-↓ blood pressure -↓ blood volume -↓Na+ concentration in blood |
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Gastrointestinal tract enteroendocrine cells
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-gastrine stimulate release of HCI
-secretin stimulates liver &pancreas -cholecstokinin stimulate pancreas, gallbladder, & hepatopancreatic sphincter |
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kidneys
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-erythropoietin signals production of red blood cells
-renin initiates the renin-angiotensin mechanism |
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skin
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cholecalciferol
the precursor of vitamin D |
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adipose
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liptin
s involved in appetite control, and stimulates ↑ energy expenditure |
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skeleton (osteoblasts)
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osteocalcine
prods (stimulate) pancreatic beta cells to divide and secrete more insulin, improving glucose handing and ↓ body fat |
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tymus
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thymulin,
thumopoietins thymosins are involved in normal the development of the Tlymphacyte in the immune response |
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mechanisms of hormone action
*hormone action on target cells (one or more could occur |
1. Alter plasma membrane permeability of membrane potential by opening or closing ion channels
2.stimulate synthesis of proteins or regulatory molecules 3.active or deactivate enzyme systems 4.induce secretory activity 5.stimulate mitosis |
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mechanisms of hormone action
2 mechanisms, depending on their chemical nature |
1.water-soluble hormones
(all amino acid- based hormone except thyroid hormone) -cannot enter the target cells -act on plasma membrane receptors -couple by G proteins to intracellular second messengers that mediate the target cells response 2. Lipid-soluble hormones (steroid, thyroid hormones) -Act on intercellular receptors that directly activate genes |
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Plasma membrane receptors and second messenger system
#1 (for water- soluble hormones) [cAMP signaling mechanism] |
cAMP signaling mechanism
1. hormone (first messenger) binds to receptor 2.Receptor activates G protein 3.G protein activate [adenylate cyclasae] 4. adynylate cyclass converts ATP- cAMP (second messenger) 5. cAMP activates protein kinases *activated kinases phosphorylate various proteins, activating some and inactivating other. *cAMP is rapidly degraded by the enzyme phosphodiesterase *intracellular enzymatic cascades have a huge amplification effect |
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Plasma membrane receptors and second messenger system
#2 [PIP2- calcium singnaling mechanism] |
-used by some amino acid based hormones in some tissues
-involves a G protein -G protein activates phospholipase C enzyme -phospholipase splits membrane phospholipid (PIP) into two second messengers: [diacylglycerol (DAG)2] & [IP3] -DAG activate protein kinases; IP3 triggers release of Ca2+ -Ca2+ alters enyzmes or channels or binds to the regulatory protein calmodulin |
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Intracellular receptors and direct gene activation
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*steroid & thyroid hormone
1. Diffuse into their target cells and bind with intracellular receptor 2.receptor-hormone complex enters the nucleus 3.receptor-hormone complex bind to a specific region of DNA 4.this prompts DNA transcription to produce mRNA 5.The mRNA directs protein synthesis |
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