What role does ADH play in the kidneys?

The role of Antidiuretic Hormone (ADH), also known as vasopressin, in the kidneys is primarily to regulate water balance in the body. ADH is secreted by the posterior pituitary gland and functions by binding to specific receptors on the cells of the kidney's collecting ducts.

When ADH binds to its receptors, it triggers a series of cellular events that lead to the insertion of water channels called aquaporins into the membranes of these cells. These aquaporins allow for increased water reabsorption from the filtrate back into the bloodstream, resulting in a more concentrated urine and decreased urine output. This mechanism is crucial in situations where the body needs to conserve water, such as during dehydration or when blood osmolality is high.

Thus, the process not only plays a critical role in maintaining proper hydration levels but also in regulating blood pressure and overall fluid balance in the organism. This understanding emphasizes the importance of ADH in kidney function and water reabsorption.