Question

⭕ 50 points ⭕

$\small\purple{explain\:your\:answer}$

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Answer 1

Answer:

To explain:

Excretion of Potassium is mainly governed by secretion of K+ from the Distal Convoluted Tubules

Explanation:

First of all, you should know that in the Distal Convoluted Tubules, there is presence of mainly 2 types of Cells

a) P cells (Principle cells)

b) I cells ( Intercalated cells)

Now, these 2 cell types have 2 different but important function.

I cells:

They perform the function of Acid - Base regulation. This is mainly done by secretion of H+ into tubular lumen and generation of alkali reserve ( i.e. HCO3-)

P cells:

These cells are responsible for secretion of K+ and absorption of Na+.

These cells contain ion channels through which the individual ions can be transported.

So option C) is correct.

Eliminating the other options:

option a) : K+ reabsorption does occur at PCT but in very small amount. Hence it doesn't govern K+ excretion.

option b) : K+ secretion doesn't occur at PCT due to lack of ion transporters.

option d) : Only K+ secretion occurs at DCT. Tubular reabsorption of K+ doesn't take place at DCT.

Answer 2

Answer:

The kidneys excrete about 15 % of the filtered K load of 10 mEq/Kg per day. ... Along the distal tubule and collecting ducts, there is net secretion of K which is stimulated by aldosterone and when there is dietary K excess. Secretion decreases and becomes net reabsorption in K deficiency.