Exam 3

Question 1

Define how the kidneys regulate GFR.

Answer 1

a. Renal autoregulation
b. Macula densa cells of the JGA sense osmolality  sends info to JGA control center which then increases or decreases NO production to constrict or dilate smooth muscle.

Question 2

Describe the function of NHE3 and carbonic anhydrase in sodium and bicarb reabsorption.

Answer 2

a. NHE3 (in the PCT):
i. It is an apical exchanger, 1 Na+ goes into PCT & 1 H+ goes into the Lumen/urine.
ii. The H+ binds to HCO3 to form carbonic acid H2CO3.
iii. The carbonic anhydrase breaks down H2CO3 into H2O & CO2.
iv. CO2 diffuses across membrane into the PCT.
v. There carbonic anhydrase turns CO2 & H2O into H2CO3.
vi. The HCO3 goes into blood stream & H+ gets exchanged into Lumen/urine via NHE3 exchanger.

b. Carbonic anhydrase:
i. If CA is blocked via Acetazolamide then HCO3 & Na+ are excreted in urine