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52 Cards in this Set
- Front
- Back
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Organs of the endocrine system
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Pineal, Hypothalamus, Pituitary
Parathyroid, thyroid thymus Heart Stomach, pancreas, duodenum Adrenal glands, kidneys Gonads and placenta |
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Functions of the endocrine system
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Control metaboism, water & electrolyte
Induce adaptive changes Regulate growth & dvlpment Control reproduction Control RBC production along with CNS, regulate circulation, nutrient digestion and absorption |
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Amine hormones
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a. derivatives of tyrosine
b. Adrenomedullary hormones are hydrophilic c. Thyroid hormones are hydrophobic |
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Synthesis of peptide hormones
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a. Preprohormones are synth'd by ribosome/golgi
b. Removal of petide sequences/sequestered with hormone c. Hormones are packaged by vesicles and stored until cell is stim'd to release by exocytosis |
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Synthesis of steroid hormones
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a. Cholesterol is principal precursor
b. synthesis requires enzyme to modify the cholesterol mol c. finished steroid hormones diffuses into blood d. some undergo further extracellular modifications |
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Synthesis of Amine Hormones
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a. have unique synthetic and secretory pathways
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Postreceptor events: hydrophobic hormones---
Chaperone proteins |
may stabilize receptor's binding site, may cover the DNA-binding portion of the receptor, unti the hormone's binding triggers release of chaperone
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Hormone response element (HRE) sequence
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the hormone-receptor complex binds DNA here
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Common charac of hormonal actions
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1. Cascade effect in target cell
2. Hormones regulate rates of existing reactions 3. usually slow and prolonged |
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The plasma concentration of free hormones is dpdent upon several factors:
( or usually by rate of secretion ) |
a. Hormone's rate of secretion
b. rate of removal from blood c. for hydrophobic hormones, its extent of binding to plasma ptns d. rate of metabolic activation |
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"master clock" for many circadian rhythms
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suprachiasmatic nucleus
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Sites of metabolism that activate hormones
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1. Liver for activation/inactivation
2. Kidneys, blood, and target cells |
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How soon are steroid hormones released from cell?
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As soon as they are synth'd and transported in bloodstream by reversibly binding with carrier plasma proteins
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RAte of hormone secretion influenced by 3 things:
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1. Neural control
2. Hormonal control, which is stimulatory(trophic hormone) or inhibitory(negative feedback) 3. Changes in plasma conc of a nutrient or electrolyte, which is controlled by the hormone in question. ie glucagon & glc, which utilizes negative feedback |
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Enteric nervous system components
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1. Sensory neurons
a. mechano, chemo, osmo 2. Local innervating neurons a some excitatory or inhibitory 3. Interneurons |
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These individual nerve plexues make up the enteric nervous system
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1. Myenteric
2. Submucosal |
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Extrinsic nerves
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a. originate outside of dig tract, innervate organs
b. Sympathetic vs parasymp(vagus) innervation c. Dual innervation coordinates activities of digestive tract |
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GI hormones include
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endocrine hormones - excite/inhibit smooth musc & exocrine cells of dig tract and endocrine cells of pancreas.
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Antrum's peristalsis controlled by gastric (& duodenal) factors:
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Gastric factors:
1) Amount of chyme 2) Fluidity of chyme duodenal factors: 1) present of fat 2) pH 3) hypertonicity 4) Distention |
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Gastric pits within oxyntic mucosa:
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1. mucous neck cells
2. Chief cells - secret pepsinogen 3. Parietal(oxyntic) cells - Hcl and intrinsic factor |
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Gastric pits of pyloric gland area
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1. secretes mucus, and some pepsinogen, but no parietal cells
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PGA endocrine cells (G cells) secrete:
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endocrine hormone gastrin - stimulates parietal and chief cells
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HCl secretion
Parietal cells produce: |
a. carbonic anhydrase
b. The H+ & carbonate ion replaces the hydrogen and chloride ions which were secreted into lumen by the pareital cell |
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Digestive activities are controlled by combination of mechanisms
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1. Synergistic autonomous mechanisms
2. Intrinsic neural reflex 3. Extrinsic neural controls 4. Hormones |
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Gastric motility and secretion are regulated by:
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1. Gastrin
2. Vagal and intrinsic nerve activity 3. enterogastrone hormones produced by Small Intestine (secretin, CCK, gastric inhib peptide) |
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Cephalic phase of gastric secretion
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Occurs before food reach stomach
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Gastric phase of gastric secretion
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a. occurs when food enters stomach
b. Stimuli include presence of ptns, alcohol, caffeine, distention |
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Intestinal phase of gastric secretion includes excitatory and inhib aspects
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1. Intestinal gastrin has stimulatory effects
2. Duodenal stimuli that inhibit gastric motility inhibit gastric secretion |
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Pancreas
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a. Exocrine cells within acini drain hydrolytic enzymes into duodenum and alkaline solution
b. endocrine cells within islets of langerhans - produce insulin and glucagon |
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Pancreatic enzymes - proteases
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a. trypsinogen
b. chymotrypsinogen c. procarboxypetidase b & c activated by trypsin |
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Liver's functions
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1. produce bile salts
2. metabolic processing of nuts 3. detoxification or degrad of body wastes 4. synth of plasma ptns 5. storage of glycogen, fats, Fe, Cu 6. Activation of vit D, together w/kidneys 7. Removal of bac and old RBC 8. Excretion of cholesterol and bilirubin |
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Functional anatomical units of liver
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Liver lobules
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Anatomy of lobules
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1. Central vein
2. On outer side of lobule a. A branch of hepatic artery b. branch of hepatic portal vein c. peripheral bile duct |
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Liver Blood flow: 1. hepatic artery and portal vein
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to enlarged capillary sinusoids to central vein
to the inferior vena cava |
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Common bile duct
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where bile canaliculi drain into pheripheral bile duct
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What controls flow of bile into duodenum
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Sphincter of Oddi
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Bile constituents
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1. Aqueous alkaline solution
2. bile salts 3 free cholesterol 4. bilirubin 5. lecithin |
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What do bile salts do?
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Assist in lipid catabolism
abosrbed by Small Intestine, returned to liver via hepatic portal, and reused |
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Bile salts assist in lipid absorption
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1. detergent action - lipid-soluble portion of bile salt adhered to lipid droplet, with negatively charged, water-soluble portion projecting out
b. coated lipid droplets repel each other |
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Bile salts assist lipid catabolism and absorption via
Micellar formation |
a. Lecithin has similar action as that of bile salts
b. Cholesterol is insoluble in water c. Structure of a micelle |
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Portions of small intestine
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1. Duodenum - first 20cm
2. Jejunum - 2.5m 3. Ilium - terminal 3.6m |
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Brush border intracellular enzymes
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a. Enterokinase
b.Disacharidases c. Aminopeptidases |
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Absorption of salts across small intestine may involve different carriers in active transport
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a. Na-Cl symport
b. Na-K-Cl symport c. Na-Glucose or Na-Amino acid symport |
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Absorption principally as sucrose, lectose, maltose
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Intracellular catabolism produce isomers of:
glucose, galac, fructose |
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Absorption of Iron
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1. Active transport across epithelium
2. Transport into blod via transferrin or 3. Stored in epithelium as ferritin |
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Calcium absorbed via
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1. aCtive transport
2. Vit D facilitates active transport |
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sympathetic and parasympathetic preganglionic fibers release
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Ach
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Parasympathetic postganglionic fibers release
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Ach
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Ach receptors (cholinergic)
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1. Nicotinic
2. Muscarinic |
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Norepinephrine(adrenergic) receptors:
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1. Alpha
2. Beta 1 3. Beta 2 |
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What parts of the brain control skeletal muscles?
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Cortex, basal nuclei, cerebellum, brain stem
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Ach binds receptor sites on motor end plate, which causes opening of chemical messenger-gated ion channel in muscle fiber membrane...results in
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Resulting influx of sodium ions and efflux of potassium ions induces end plate potential (EPP)
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