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Anatomy 2 Ch1
Endocrine system or whatever
| Question | Answer |
|---|---|
| Hormones help regulate: | extracellular fluid, metabolism, biological clock. contraction of cardiac & smooth muscle, glandular secretion, some immune functions, Growth & development, Reproduction |
| Exocrine glands | secrete products into ducts which empty into body cavities or body surface–[sweat, oil, mucous, & digestive glands] |
| Endocrine glands | secrete products (hormones) into bloodstream– [pituitary, thyroid, parathyroid, adrenal, pineal] |
| other organs that secrete hormones as a 2nd function | hypothalamus, thymus, pancreas,ovaries,testes, kidneys, stomach, liver, small intestine, skin, heart & placenta |
| Hormones only affect ___ with specific membrane proteins called ____ | target cells;receptors |
| Receptors are constantly being ... | synthesized and broken down. |
| Down-regulation | excess hormone leads to a decrease in number of receptors; receptors undergo endocytosis and are degraded–decreases sensitivity of target cell to hormone |
| Up-regulation | deficiency of hormone leads to an increase in the number of receptors–target tissue becomes more sensitive to the hormone |
| Circulating hormones | Go everywhere in body; circulate |
| Local hormones | paracrines, autocrines |
| paracrines | Adjacent cells alerted |
| Autocrine | cell that releases the hormone is also the target cell |
| Lipid-soluble hormones: | steroids, thyroid hormones, and nitric oxide [Cortisol and thyroxine] |
| Water-soluble hormones: | amines; peptides, proteins, glycoproteins, and eicosanoids. [Insulin and TSH] |
| Protein hormones circulate in free form in blood. -Why? | They stay in circulatory system and aren’t exited from body by means like urination |
| Steroid (lipid) & thyroid hormones must... | attach to transport proteins synthesized by liver |
| Why Lipid & thyroid hormones attach to transport proteins | improve transport by making them water-soluble, slow loss of hormone by filtration within kidney, create reserve of hormone |
| free fraction | only 0.1% to 10% of hormone is not bound to transport protein |
| When hormones bind to receptors, cells may then... | synthesize new molecules, change permeability of membrane, alter rates of reactions |
| Hepatocytes: | Majority of liver cells. Cells are involved in: Protein synthesis. Protein storage. [insulin stimulates glycogenesis] |
| Adipocytes: | Cell specialized for the storage of fat, found in connective tissue. [insulin stimulates triglyceride synthesis] |
| Action of Lipid-Soluble Hormones | Hormone diffuses through phospholipid bilayer & into cell •Binds to receptor turning on/off specific genes•New mRNA is formed & directs synthesis of new proteins•New protein alters cell’s activity |
| Water-soluble hormones alter cell functions by ... | activating plasma membrane receptors, which set off a cascade of events inside the cell. |
| The water-soluble hormone that binds to the cell membrane receptor is... | the first messenger |
| A second messenger (usually cAMP) ... | is released inside the cell where hormone stimulated response takes place. |
| Order of events in water-soluble hormone | Hormone binds to receptor, Receptor activates G-protein insides cell, G-protein activates cAMP |
| Amplification of Hormone Effects example | Single molecule of hormone binds to receptor•Activates 100 G-proteins•Each activates an adenylate cyclase molecule which then produces 1000 cAMP•Each cAMP activates a protein kinase, which may act upon 1000’s of substrate molecules |
| Permissive effect | Asecond hormone, strengthens the effects of the first [ex:thyroid strengthens epinephrine’s effect upon lipolysis] |
| Synergistic effect– | two hormones acting together for greater effect [ex:estrogen & LH are both needed for oocyte production] |
| Antagonistic effects– | two hormones with opposite effects [ex:insulin promotes glycogen formation & glucagon stimulates glycogen breakdown] |
| Hormone secretion is regulated by... | signals from nervous system, chemical changes in the blood or by other hormones |
| Negative feedback control | (most common)–decrease/increase in blood level is reversed |
| Positive feedback control | the change produced by the hormone causes more hormone to be released [ex: oxytocin in childbirth] |
| Posterior pituitary stores | adh and oxytocin. Does not produce hormones |
| Anterior pituitary (not attached to hypothalamus) | Makes many hormones. |
| the major integrating link between the nervous and endocrine systems. | Hypothalamus |
| Hypothalamus receives input from ... | cortex, thalamus, limbic system & internal organs |
| Hypothalamus controls ... | pituitary gland with 9 different releasing & inhibiting hormones |
| Regulate virtually all aspects of growth, development, metabolism, and homeostasis. | hypothalamus and the pituitary gland (hypophysis) |
| pituitary gland is located in the | sella turcica of the sphenoid bone and is differentiated into the anterior pituitary, the posterior pituitary, and pars intermedia (avascular zone in between). |
| Attached pituitary to the brain | Infundibulum |
| Anterior lobe (75%) develops from | roof of mouth |
| Posterior lobe (25%) | ends of axons of 10,000 neurons found in hypothalamus–neuroglial cells called pituicytes |
| The blood supply to the anterior pituitary is from the | superiorhypophyseal arteries. |
| Hormones of the anterior pituitary | Human growth hormone (hGH);Thyroid-stimulating hormone (TSH); Follicle-stimulating hormone (FSH); Luteinizing hormone (LH); Prolactin (PRL); Adrenocorticotrophic hormone (ACTH); Melanocyte-stimulating hormone (MSH) |
| Negative Feedback Systems | Decrease in blood levels•Receptors in hypothalamus & thyroid•Cells activated to secrete more TSH or more T3 & T4•Blood levels increase |
| Positive Feedback | Oxytocin stimulates uterine contractions•Uterine contractions stimulate oxytocin release•More oxytocin = more contractions•More contractions = more oxytocin |
| the most plentiful anterior pituitary hormone. | Human growth hormone (hGH) |
| hGH acts indirectly on tissues by promoting ... | the synthesis and secretion of small protein hormones called insulin-like growth factors (IGFs). |
| insulin-like growth factors (IGFs) | IGFs stimulate general body growth and regulate various aspects of metabolism. Various stimuli promote and inhibit hGH production |
| Regulation of hGH, low blood sugar | Low blood sugar stimulates release of GHRH (Growth hormone-releasing hormone) from hypothalamus–anterior pituitary releases more hGH, more glycogen broken down into glucose by liver cells |
| Regulation of hGH, high blood sugar | •High blood sugar stimulates release of GHIH (growth hormone-inhibiting hormone) from hypothalamus–less hGH from anterior pituitary, glycogen does not breakdown into glucose |
| Follice Stimulating hormone (FSH) functions | initiates the formation of follicles within the ovary–stimulates follicle cells to secrete estrogen–stimulates sperm production in testes |
| Luteinizing hormone (LH) in females stimulates... | secretion of estrogen–ovulation of 2nd oocyte from ovary–formation of corpus luteum–secretion of progesterone |
| In males, LH stimulates ... | the interstitial cells of the testes to secrete testosterone. |
| Prolactin (PRL) | together with other hormones, initiates and maintains milk secretion by the mammary glands. |
| Adrenocorticotrophic hormone (ACTH) | controls the production and secretion of hormones called glucocorticoids by the cortex of the adrenal gland–Mainly cortisol which can elevate BP and blood glucose levels. |
| Melanocyte-stimulating hormone (MSH) | increases skin pigmentation although its exact role in humans is unknown |
| Hormones made by the hypothalamus and stored in the posterior pituitary are | oxytocin (OT) and antidiuretic hormone(ADH). |
| Oxytocin during delivery | baby’s head stretches cervix stimulating oxytocin release which nhances uterine muscle contraction helping deliver baby & placenta |
| Oxytocin after delivery | Oxytocin stimulates contraction of the uterus and ejection (let-down) of milk from the breasts. |
| Antidiuretic hormone (ADH) | stimulates water reabsorption by the kidneys and arteriolar constriction.–The effect of ADH is to decrease urine volume and conserve body water. |
| The thyroid gland is located... | just below the larynx and has right and left lateral lobes. On each side of trachea is lobe of thyroid•Weighs 1 oz & has rich blood supply |
| Follicular cells produce... | thyroxine (T4), triiodothyronine (T3) [The number stands for the amount of iodine] |
| Parafollicular cells produce... | calcitonin; Involved in calcium homeostasis. Brings calcium levels down when too high |
| Formation of Thyroid Hormone | Iodide trapping by follicular cells•Synthesis of thyroglobulin (TGB)•Release TGB into colloid•Iodination of tyrosine in colloid•Formation of T3&T4 by combining T1 and T2 together•Uptake & digestion of TGB by follicle cells•Secretion of T3 & T4 into blood |
| Thyroxine(T3) &Triiodothyronine (T4 ) | thyroid hormones responsible for our metabolic rate, synthesis of protein, breakdown of fats, use of glucose for ATP production |
| Calcitonin | responsible for building of bone & stops reabsorption of bone (lowers blood levels of Calcium) |
| The parathyroid glands are embedded on... | the posterior surfaces of the lateral lobes of the thyroid. 4 pea-sized glands found on back of thyroid gland |
| Principal cells of parathyroid gland produce | parathyroid hormone |
| Parathyroid hormone (PTH) regulates ... | the homeostasis of calcium and phosphate |
| Parathyroid Hormone (PTH) | increase blood Ca lvl&decrease blood phosphate lvl–increases number&activity of osteoclasts–increase rate of Ca&Mg reabsorption from urine & inhibits production in urine–promotes formation of calcitriol which increases absorption of Ca, Mg& HPO4-2 from GI |
| High or low blood levels of Ca+2 stimulates the release of different hormones... | PTH or CT |
| The adrenal glands are located ... | superior to the kidneys. 3 x 3 x 1 cm in size and weigh 5 grams |
| Adrenal glads consist of... | an outer cortex and an inner medulla |
| Cortex produces ... | 3 different types of hormones from 3 zones of cortex |
| Medulla produces | epinephrine & norepinephrine |
| Zona glomerulosa secretes | mineralocorticoids, mainly alosterone |
| Zona fasciculata secretes | glucocorticoids, mainly cortisol |
| Zona reticularis secretes | androgens |
| Mineralocorticoids activity | 95% of hormonal activity due to aldosterone |
| Functions of mineralocorticoids | Increase reabsorption of Na+ with Cl-, with bicarbonate and water following it–promotes excretion of K+ and H+ |
| Hypersecretion of mineralocorticoids= | tumor producing aldosteronism. High blood pressure caused by retention of Na+ and water in blood |
| Regulation of Aldosterone | Dehydration,Na deficient/hemmorage, increased angiotensin II to adrenal cortex, increases aldosterone, in kidneys increased reabsorb of Na and water&secretion of K &H into blood, Increase blood volume |
| Glucocorticoids activity | 95% of hormonal activity is due to cortisol. Help regulate metabolism. |
| Functions of glucocorticoids | increase rate of protein catabolism&lipolysis–conversion of amino acids to glucose–stimulate lipolysis–provide resistance to stress by making nutrients available for ATP production–raise BP by vasoconstriction–anti-inflammatory effects reduced |
| anti-inflammatory effects reduced by glucocorticoids | Skin cream; reduce release of histamine from mast cells•decrease capillary permeability•depress phagocytosis |
| Androgens | From Zona Reticularis ; insignificant in males–may contribute to sex drive in females–is converted to estrogen in postmenopausal females |
| Chromaffin cells (Located in Adrenal medulla) | Receive direct innervation from sympathetic nervous system. develop from same tissue as postganglionic neurons |
| Adrenal Medulla | Produce epinephrine & norepinephrine•Hormones are sympathomimetic(effects mimic those of sympathetic NS–cause fight-flight behavior)•Acetylcholine increase hormone secretion by adrenal medulla |
| _____ increase hormone secretion by adrenal medulla | Acetylcholine |
| Fight of flight | The alarm reaction is initiated by nerve impulses from the hypothalamus to the sympathetic division of the autonomic nervous system and adrenal medulla |
| Fight or flight response has this effect... | increased circulation to large muscles–promote catabolism for energy production–promotes ATP synthesis–nonessential body functions are inhibited(digestive, urinary & reproductive) |
| Pancreatic islets | On pancrease (which is endo&exocrine gland). Also called islets of Langerhans. |
| Cell Types in the Pancreatic Islets (that we're studying) | Alpha and Beta cells |
| Alpha cells | (20%) produce glucagon |
| Beta cells | (70%) produce insulin |
| Ovaries: | estrogen, progesterone, relaxin & inhibin–regulate reproductive cycle, maintain pregnancy & prepare mammary glands for lactation |
| Testes: | produce testosterone–regulate sperm production & 2nd sexual characteristics |
| Pineal Gland | Small gland attached to 3rd ventricle of brain–Consists of pinealocytes & neuroglia–Melatonin responsible for setting of biological clock–Jet lag & SAD treatment is bright light |
| Growth Factors | Substances with mitogenic qualities–cause cell growth from cell division. Many act locally as autocrines or paracrines |
| Selected list of growth factors | epidermal growth factor (EGF), platelet-derived growth factor (PDGF), fibroblast growth factor (FGF), nerve growth factor (NGF), tumor angiogenesis factors (TAFs), Insulin-like growth factor (IFG), cytokines |
| Stress response is set of bodily changes called | general adaptation syndrome (GAS) |
| Eustress: | Productive stress & helps us prepare for certain challenges |
| Distress: | Harmful stress; lower our resistance to infection |
Created by:
Devtemrys
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