Which of the following statemetns is correct?a)Water reabsorption in d...
Water reabsorption in descending limb of loop of Henle and collecting duct occurs under different conditions. In descending limb, water is reabsorbed due to increasing osmolarity of interstitial fluid. Collecting duct is entirely permeable to water. Water is reabsorbed here, under the influence of anti-diuretic hormone (ADH), which is released into the blood from the posterior lobe of pituitary gland.
View all questions of this test
Which of the following statemetns is correct?a)Water reabsorption in d...
Water reabsorption in the descending limb of the loop of Henle and the collecting duct occur under different conditions.
Explanation:
- Water reabsorption in the descending limb of the loop of Henle:
In the descending limb of the loop of Henle, water reabsorption occurs passively. This means that water moves out of the tubules and into the surrounding interstitial fluid (fluid between the cells) due to the osmotic gradient created by the high concentration of solutes in the medulla. The descending limb is permeable to water, but not to solutes. Therefore, water moves out of the tubules and into the interstitial fluid, leading to an increase in the concentration of solutes in the tubular fluid.
- Water reabsorption in the collecting duct:
In the collecting duct, water reabsorption can occur in two different conditions - under the influence of antidiuretic hormone (ADH) and in the absence of ADH.
1. Water reabsorption in the presence of ADH:
When ADH is present, it binds to receptors on the cells of the collecting duct, causing the insertion of aquaporin channels into the cell membrane. Aquaporins are water channels that allow water to move through the cell membrane. As a result, water moves out of the tubules, through the aquaporin channels, and into the interstitial fluid. This leads to concentrated urine.
2. Water reabsorption in the absence of ADH:
When ADH is absent, the aquaporin channels are not inserted into the cell membrane, and water reabsorption is reduced. As a result, more water remains in the tubules, leading to the production of dilute urine.
- Difference between water reabsorption in the descending limb and the collecting duct:
The key difference between water reabsorption in the descending limb of the loop of Henle and the collecting duct is the mechanism involved. In the descending limb, water reabsorption occurs passively, while in the collecting duct, it occurs under the influence of ADH or in the absence of ADH. Additionally, the permeability of the tubules to water is different in these two segments. The descending limb is highly permeable to water, while the permeability of the collecting duct depends on the presence or absence of ADH.
To make sure you are not studying endlessly, EduRev has designed NEET study material, with Structured Courses, Videos, & Test Series. Plus get personalized analysis, doubt solving and improvement plans to achieve a great score in NEET.