Question

During the process of turning filtrate into urine,

Group of answer choices

the proximal tubule and Loop of Henle are responsible for reabsorbing most of the water and Na+.

Water is reabsorbed only in the collecting ducts.

The Loop of Henle decreases filtrate volume by removing water from the filtrate in the ascending limb.

Secretion of H+ occurs only in the proximal tubule.

Answer 1

Correct choice is

1. the proximal tubule and Loop of Henle are responsible for reabsorbing most of the water and Na+

Now let's see and discuss each options :

1. After the ultrafiltration of solute in the Glomerular capillary the filterate is collected in Bowman's Capsule. Of this filterate 60-70% of solute and water are reabsorbed in the Proximal convoluted tubules. Then in the decending limb of loop of henle (which is freely permiable to water, but impermeable to solute) water gets reabsorbed. In ascending limv of loop of henle (which is impermeable to water but freely permiable to solute) sodium and other ions gets reabsorbed. Hence, this option is correct.

2." Water is reabsorbed only in the collecting ducts. " This option is wrong cause in Collecting duct only ADH / aldosterone dependent water reabsorption takes place. Most of the water gets reabsorbed in the Proximal convoluted tubule.

3. "The Loop of Henle decreases filtrate volume by removing water from the filtrate in the ascending limb." This option is also wrong as ascending Limb of loop of henle is impermeable to water. Hence, no water reabsorption takes place in the ascending limb of loop of henle.

4. "Secretion of H+ occurs only in the proximal tubule." This option is wrong because most of the secretion of H+ ion occurs in DCT and CD depending upon the action of aldosterone.