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21 Cards in this Set
- Front
- Back
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normal urine concentration
total body cortex medulla PCT DCT |
body 30-1200 mOsm
cortex 300 medulla 1200 PCT 300 DCT 100 |
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main regulator of total body fluid
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concentration/dilation of urine
kidneys can: -concentrate by 4 fold -dilute by 10 fold |
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componants of CCM
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PCT
-osm balance w/cortex descending loop -not perm Na -lots of water out ascending loop -not perm water -Na, Cl out vasa recta flow in opposite dir |
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role of vasa recta
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absorb Na & H2O
slow flow (unless hypervolemic conditions) |
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affect of increased flow rate in vasa recta
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medulla interstitium lower mOsm
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ADH is synthesized in...
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Hypothalamus
supraoptic and paraventricular nuclei |
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regulators of urine concentration
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ADH
Urea Thirst |
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ADH secreted in response to...
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high plasma osmolality
low plasma volume |
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ADH secreted from
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posterior pituitary
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osmoreceptors for ADH in
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OVLT
SFO sensitized by volume depletion (desens by exp) |
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set point for osmoreceptors
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285-295 mOsm
sharp curve after that |
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mech of action for ADH
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increase expression aquaporin
-V2 R on principal cell (CD) -GPCR, activate cAMP -phosphorylate prot in vesicle cAMP dependent increase reabsorp urea |
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result of ADH binding in CD
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increased aquaporin expression
increased urea reabsorption (out of medullary collecting duct) |
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affect of COX inhibitors on ADH
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PGE2 stimulated by ADH
blunts antidiuresis COX inhibitors enhance ADH water resoprtion |
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urea filtration/reabsorption characteristics
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freely filtered
passive reabsorbed at PCT ADH increases reabsorp at Medullary CT |
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affect of high protein diet on water content of body
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increased Urea
increased osmotic drive water out into medulla |
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thirst stimulated by
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increased plasma osmolality
(2mEq/L) decreased plasma volume increased AT II dry mouth (independent of body solute) decrease stim w/gastric distention |
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free water
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measurement of difference from isoosmotic urine
CH2O = V - Cosm (Cosm = GFR) |
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hypoosmotic urine,
pos or neg CH2O |
positive- water excreted
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hyperosmotic urine,
pos or neg CH2O |
negative- water conserved
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thirst osmorerecptors activate
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thirst
Na appetite (activates RAS) |
