Question 5

Increase in water reabsorption in the collecting duct

The release of anti-diuretic hormone (ADH) primarily leads to an increase in water reabsorption in the collecting duct of the kidneys. This mechanism is crucial for regulating the body's water balance and maintaining proper hydration levels.

A) Decrease in water reabsorption in the collecting duct

This option is incorrect as the action of anti-diuretic hormone is to enhance water reabsorption. Instead of decreasing reabsorption, ADH facilitates the insertion of aquaporin channels in the collecting duct, allowing more water to be reabsorbed back into the bloodstream.

B) Decrease in the concentration of calcium in the glomerulus

This option does not directly relate to the function of anti-diuretic hormone. ADH primarily affects water reabsorption rather than calcium concentration in the glomerulus, which is influenced by other hormones and renal processes.

C) Increase in the concentration of calcium in the glomerulus

This choice is also incorrect, as ADH does not increase calcium concentration in the glomerulus. The action of ADH is focused on water reabsorption mechanisms and does not directly alter calcium levels in this part of the kidney.

D) Increase in water reabsorption in the collecting duct

This option is correct as ADH promotes the retention of water by increasing its reabsorption in the collecting ducts of the kidneys. This process helps to concentrate urine and regulate the body's fluid balance efficiently.

Conclusion

The correct answer, which highlights the increase in water reabsorption in the collecting duct due to the release of anti-diuretic hormone, is fundamental to understanding how the body maintains fluid homeostasis. All other options misrepresent the role of ADH, focusing on aspects unrelated to its primary function of enhancing water retention in the kidneys.