Reg Urine Osmolarity

Question 1

low water intake or inc water loss

Answer 1

kidneys need to conserve water so small volume of hyperosmotic urine

Question 2

high water intake

Answer 2

kidneys don’t need to conserve so large volume of hypoosmotic urine

Question 3

ADH mechanism

Answer 3

1. inc in fluid osmolarity/inc sodium concentration
2. osmoreceptor cells shrink
3. signal supraoptic nuclei of pituitary gland to relase ADH
4. bind to receptors in collecting duct to inc water perm and inc reabsorption/dec excretion

Question 4

thirst mechanism

Answer 4

1. large dec in circulating blood vol or BP, hemorrhage, dry mouth/throat
2. thirst osmoreceptors stimulated to inc water intake

Question 5

countercurrent multiplier purpose

Answer 5

reabsorb water @ loop of henle to create gradient of inc osmolarity and hyperosmotic medullary interstitium

Question 6

countercurrent exchange purpose

Answer 6

maintain osmolarity gradient/hyperosmotic medullary interstitum @ vasa recta

Question 7

descending loop is permeable to

Answer 7

water, not sodium

Question 8

ascending loop permeable to

Answer 8

sodium, not water

Question 9

if countercurrent mechanism interrupted

Answer 9

large vol of diluted urine
-can also happen if low ADH or not resp to it

Question 10

urea importance

Answer 10

contributes to hyperosmolarity of renal medulla

Question 11

urea recycling pathway

Answer 11

filtered urea reabsorbed by proximal tubule and collecting duct > secreted back into descending loop > reabsorbed back into collecting duct