Term
max: 1200-1400 mOsm/L specific g: 1.030
min: 50-70 mOsm/L specific g: 1.003 |
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Definition
| what is the maximal urine concentration? what is the minimum? |
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Term
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Definition
| how are urine osmolarity and specific gravity related? |
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Term
| glucose in the urine and protein in the urine |
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Definition
| what influences urine osmolarity/specific gravity? |
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Term
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Definition
| is water excretion the same as solute excretion? |
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Term
adh will be low if you are well hydrated
urine will be hypotonic (for about 2 hours) |
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Definition
| if you drink a liter of water, what happens to your ADH levels? describe the concentration of your urine |
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Term
1) absorb electrolytes, but not water
2) decrease ADH, and decrease H2O permeability in DCT/collecting duct
3) high osmolarity in the renal medulla maintained via countercurrent exchange |
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Definition
| how do you form dilute urine? |
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Term
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Definition
| the minimum volume in which ingested solutes can be dissolved and excreted |
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Term
| 600 mOsm/day / 1200 mOsm/ L = 0.5 L/day |
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Definition
| if the max urine osmolarity is 1200 mOsm/L and 600 mOsm of solute must be excreted to maintain electrolyte balance each day, what is the obligatory urine volume? |
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Term
| the max urine osmolarity the kidneys can produce ex: if you can only concentrate to 300 mOsm/L and you still need to get out 600, the obligatory volume is now 2.0 L/day to get out all the solutes |
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Definition
| what determines the obligatory urine volume? |
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Term
| arginine vasopressin (AVP) |
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Definition
| whats another name for antidiuretic hormone (ADH) |
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Term
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Definition
| what allows for differential control of H2O and solute excretion? (this is important in controlling ECF osmolarity) |
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Term
1)vasopressin binds to a g protein coupled receptor
2) CAMP caskade -> pKa -> phosphorylation
3) causes immigration of aquaporin 2 channels to the luminal membrane to allow H2O reabsorption |
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Definition
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Term
| countercurrent exchange (basically the artery and vein are close enough to each other the heat is transferred before the fluid circulates, preventing heat loss & keeping it close to the body, while maintaining flow |
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Definition
| what does thermoregulation in a seagull's leg illustrate? |
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Term
1) tri-pump active transport to medullary interstitium
2) active transport of ions from medullary collecting ducts to interstitium
3) passive diffusion of urea from medullary collecting ducts to interstitium
4) diffusion of little H2O to medullary interstitium |
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Definition
| how is the medullary concentration increased? |
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Term
| paracellular diffusion in thick ascending limb |
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Definition
| how are Mg and Ca++ reabsorbed? |
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Term
| anatomical relationships of LoH, vasa recta, & collecting ducts |
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Definition
| what does the countercurrent multiplier mechanism depend on? |
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Term
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Definition
| how many nephrons are juxtamedullary with long LoH in the medulla? |
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Term
| H2O absorption in descending LoH |
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Definition
| what enhances the high osmolarity of the interstitium in the medulla? |
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Term
|
Definition
| when is the countercurrent gradient established? |
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Term
|
Definition
| where does the LoH receive continuous NaCl from? |
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Term
| anywhere there is a pump, but thick ascending limb is important |
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Definition
| where is there continuous resorption of NaCl into the interstitium? |
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Term
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Definition
| describe the ascending limb's permeability to water |
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Term
|
Definition
| describe the ascending limb's permeability to water |
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Term
| Na+ and H2O both (plus other junk) |
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Definition
| what is the descending limb permeable to? |
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Term
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Definition
| what helps to dilute the cortical interstitium & maintain the osmolar gradient? |
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Term
| after filtration, helps to re-absorbe H2O in DCT with help of ADH, this concentrates the urine |
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Definition
| when is blood in the vasa recta concentrated? what does this do? |
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Term
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Definition
| when solute leaves the vasa recta's ascending loop, where is it reabsorbed? |
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|
Term
| where it passes the descending LoH |
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Definition
| where does high concentrated solute begin to enter the vasa recta? |
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|
Term
|
Definition
| what percent of renal blood flow do the vasa recta make up? |
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|
Term
|
Definition
| what are the counter current exchangers to the renal tubules? |
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|
Term
1) more solute than H2O is added to the renal medulla (solutes are trapped here)
2) fluid in the ascending loop is diluted
3) most of the H2O reabsorption occurs in the cortex (PCT, DCT) not the medulla
3) horizontal gradient of solute concentration established by the active pumping of NaCl is multiplied by the countercurrent flow |
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Definition
| what are the net effects of the countercurrent multiplier? |
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Term
|
Definition
| where is urea passively reabsorbed? |
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Term
| distal and collecting tubules |
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Definition
| where is water resabsorbed in the presence of ADH to concentrate urea? |
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Term
| the medullary collecting tubule (urea diffuses into the interstitium here) |
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Definition
| what tubule is HIGHLY permeable to urea? |
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|
Term
|
Definition
| what does ADH do to urea permeability in the medullary collecting tubule? |
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|
Term
50% of filtered urea is reabsorbed in the PCT
then the countercurrent mechanism pumps urea from the collecting tubule back into the thin LoH in the medulla which ends up reconcentrating it at the DCT |
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Definition
| where is 50% of urea reabsorbed? why does the DCT have 100% of the urea back in it? |
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Term
| only 20%, the rest is reabsorbed to help with the concentration gradient |
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Definition
| how much urea is excreted in each pass through the nephron? |
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|
Term
1) GFR
2) plasma urea concentration |
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Definition
| what determines rate of urea excretion? |
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Term
|
Definition
| abnormal elevation of urea in the plasma |
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|
Term
everywhere but the thin limbs
ESPECIALLY in the thick ascending and PCT |
|
Definition
| where is sodium actively reabsorbed? |
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|
Term
|
Definition
| where is sodium passively reabsorbed? |
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|
Term
reabsorbed: PCT, thin descending
NOT: thin ascending, thick ascending
with ADH: DCT, all collecting tubule |
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Definition
| where is water reabsorbed? where is it NOT? where does it depend on ADH? |
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|
Term
reabsorbed: PCT, thin loops (both)
+ ADH: medullary collecting tubule |
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Definition
| where is urea reabsorbed? with ADH? |
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|
Term
| urine flow rate - [(urine osmolarity * urine flow rate) / plasma osmolarity] |
|
Definition
| what is the equation for free water clearance (CH2O?) |
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|
Term
|
Definition
| what is free water clearance if urine osmolarity is greater than plasma osmolarity? |
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