Water ions, and acid-base balances

Question 1

Kidney conserve volume

Answer 1

-kidneys cannot make up lost water volume, it can only shut down excretion
-if volume decreases to a certain level, you can damage your GFR
-important to drink water

Question 2

Osmolarity changes through the nephron

Answer 2

-when going down deeper into the loop of henle, osmolarity increases (1200 mOsM)
-when going up the ascending loop osmolarity decreases (100 mOsM)

Question 3

What is vasopressin?

Answer 3

a hormone that controls water reabsorption in the collecting duct (produced by hypothalamus)

Question 4

What does vasopressin do to regulate water reabsorption?

Answer 4

-vasopressin acts as a water channel
renal system membrane is impermeable to water
so more vasopressin =more water reabsorption
absence of vasopressin: urine is diluted (no water reabsorbed)

Question 5

Where does reabsorbed water go?

Answer 5

it goes to the peritubule where water goes to blood and gets carried away so it wont mess up the concentration gradient

Question 6

How does vasopressin work?

Answer 6

1. vasopressin binds to membrane receptor
   2.receptor activates second messenger cAMP
2. AQP2 water pores go to apical membrane
3. water absorbed by osmosis into the blood

more aquaporins makes membrane more permeable to water

Question 7

How does beer affect vassopressin?

Answer 7

-vasopressin is inhibited by beer so water does not go through peritubule

Question 8

What triggers vasopressin release?

Answer 8

-decreased blood pressure
-decreased atrial stretch due to low blood volume
-osmolarity greater than 280 mOsM

Question 9

Loop of Henle

Answer 9

-the descending part is dedicated to the reabsorption of water to vasa recta (outside environment concentrated)
-in the ascending part it is impermeable to water and is dedicated to ion reabsorption into vasa recta (outside environment becomes diluted)