Question

In which of the following segments of the nephron, the antidiuretic hormone stimulates insertion of aquaporins when a person Is dehydrated?

Select one:

_ a. Early distal tubules

b. Collecting ducts

C. Thin ascending loop of Henle

d. Proximal convoluted tubule

Answer 1

Answer) option B- collecting duct

Explanation - Antidiuretic hormone is secreted from anterior pituitary gland, when the person is dehydrated.

Antidiuretic hormone increases the permeability of collecting duct to water by increasing the pore size through aquaporin-2 channels.

So, water is reabsorbed from collecting duct.

As water is reabsorbed, the volume of urine decreases and concentration of urine is increases.

Other options are incorrect -

Option A is incorrect -

-Distal convoluted tubule consists of 2 parts - early distal convoluted tubule and late distal convoluted tubule.

Like collecting duct, antidiuretic hormone also increases permeability of late distal convoluted tubule (not early distal tubule).

Early distal convoluted tubule is impermeable to water.

It is permeable to ions like sodium, chloride and calcium.

Option C is incorrect -

As thin ascending limb of loop of henle is impermeable to water. So, filtrate becomes progressively more dilute as it moves up to the cortex (towards the distal convoluted tubule)

It is permeable to sodium and chloride ions and also to urea.

Option D is incorrect -

As proximal convoluted tubule reabsorps 70 to 80 percent of the filtered sodium, chloride, bicarbonate ions and water.

It is permeable to water but it is not under influence of antidiuretic hormone.