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19 Cards in this Set
- Front
- Back
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gluconeogenesis
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breakdown of amino acids in kidneys to form glucose in extreme starvation
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urea
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a nitrogenous waste formed when proteins break down into amino acids and the NH2 (amino-) group is removed, forming ammonia, which is converted to urea in the liver
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azotemia
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an elevated level of nitrogenous waste in the blood
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uremia
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diarrhea, vomiting, dyspnea, and cardiac arrhythmia stemming from the toxicity of nitrogenous waste
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blood flow in kidneys
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afferent arteriole-->glomerulus-->efferent arteriole--->peritubular capillaries(cortex)/vasa recta(medulla)
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renal corpuscle
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consists of 2-layered Bowman's capsule and the glomerulus
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proximal convoluted tubule
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arises from renal corpuscle, this is the first segment of the nephron. It achieves MOST of the kidney reabsorption, that is, many substances are taken from the filtrate and returned to the blood via active transport (Na+K+ pump). It has prominent microvilli for absorbtion.
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loop of Henle
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a U-shaped portion of the nephron after the PCT, has an ascending and descending limb.
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distal convoluted tubule
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begins when the nephron loop reenters the cortex, a lot of secretion occurs here...H+ ions and K+ ions are secreted into the urine from the blood...no microvilli
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collecting duct
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many DCTS feed into a collecting duct, whose primary function is to concentrate the urine...many CDs form a papillary duct--->minor calyx
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renal plexus
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nerves and ganglia wrapped around each renal artery
SYMP: reduce glomerular blood flow/urine formation PARA: increase rate of urine production |
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glomerular filtration
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this is the process by which materials in the glomerular capillaries pass into Bowman's capsule
...pass through---fenestrated (holey) epithelium of glomerular capillaries, negatively charged basement membrane (albumin/anionic proteins repelled), and filtration slits formed by podocytes ---some materials that must be reabsorbed later DO pass through at this point (glucose) ----RBCs, proteins, protein bound hormones, should NOT pass through at this point (too large) net filtration pressure: 10 mm Hg |
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GFR
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glomerular filtration rate
net filtration pressure (~10 mm Hg) x filtration coefficient 125 mL/ min - male ....180 L/day (99% is reabsorbed) |
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high GFR
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fluid flows too fast for tubules to reabsorb materials, urine output increases, risk of dehydration
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low GFR
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wastes are reabsorbed...azotemia
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renal autoregulation of GFR
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nephrons exert their own control over over glomerular blood flow w/o external intervention
-myogenic mechanism: smooth muscle has a "bad attitude" and contracts when stretched...so GFR can't rise too high -tubuloglomerular feedback: employs juxtaglomerular apparatus (at end of nephron) to "check up on" downstream fluid and regulate itself/compensate for fluctuations |
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juxtaglomerular apparatus
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located b/w afferent and efferent arteriole at end of nephron loop, has 3 kinds of cells that regular GFR
1. macula densa: sensory cells, monitor variations in flow or fluid composition...then secretes a paracrine to alert the JG cells. 2. juxtaglomerular cells are activated by paracrines secretes by the macula densa, they are enlarged smooth muscle cells that are able to dilate/constrict the arterioles OR secret renin, which acts in the RAAS hormone system 3. mesangial cells: cells located in the cleft between the ef/af arterioles that communicate w/ macula densa and juxtaglomerular cells w/ paracrines the dilate/constrict glomerular CAPPILLARIES (not arterioles like JG cells), they also build supportive matrix for glomerulus |
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sympathetic control of GFR
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sympathetic nerve fibers richly innervate the renal blood vessels, so during sympathetic stimulation the afferent arterioles constrict to slow urine formation and reroute blood to brain, muscles, and other areas that need it.
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RAA mechanism
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the hormone renin, is secreted by the JG cells of the juxtaglomerular apparatus, renin converts angiotensinogen from blood to angiotensin I....ACE in lungs/kidneys converts angiotensin I to angiotensin II, which is a potent vasoconstrictor...constricts Efferent arteriole raising GFR, lowers BP in peritubular capillaries increasing reabsorption...and stimulates the release of aldosterone/ADH
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