RTA

Question 1

How kidney responds to decreased pH (i.e more H+)?

Answer 1

It reabsorbs HCO3- and excretes H+. It does the opposite if pH is increased.

Question 2

Where are HCO3- primarily reabsorbed? Where is H+ primarily secreted?

Answer 2

Proximal convoluted tubule and a intercalated cells respectively.

Question 3

Does the kidney also buffer the extra H+ with HCO3-?

Answer 3

No, in the PCT there is no net movement of H+, only HCO3- is reabsorbed or secreted.

Question 4

How does kidney remove the extra protons?

Answer 4

By making NH3 (a intercalated cells) or phosphate. Ammonia and phosphate buffer the H+.

Question 5

Why is that needed; since they are ions, can’t they be excreted by themshelves?

Answer 5

Yes, but they are toxic to the tubules in such high concentrations.

Question 6

What happens if the kidney fails to reabsorb HCO3?

Answer 6

RTA type II (proximal, damage mainly of PCT)

Question 7

What happens if the kidney fails to secrete H+?

Answer 7

RTA type I (distal, damage mainly of a intercalated cells)

Question 8

What happens if kidney fails to produce NH3?

Answer 8

RTA type IV (a low renin-low aldo state, with damage mainly of principal cells)