Final answer:
Antidiuretic hormone (ADH), also known as vasopressin, targets the collecting ducts in the kidneys to promote water reabsorption, reduce urine volume, and act as a vasoconstrictor to help maintain blood pressure.
Step-by-step explanation:
Antidiuretic Hormone (ADH) Targets and Functions
The antidiuretic hormone (ADH), also known as vasopressin, primarily targets the kidney cells, specifically the collecting ducts in the kidneys. ADH is produced by the hypothalamus and released from the posterior pituitary gland. The primary action of ADH is to promote water reabsorption and reduce urine output by making the collecting ducts more permeable to water. This occurs through the movement of aquaporins, which are water channels, into the apical membrane of kidney tubule cells.
ADH also has a role in constricting peripheral blood vessels, acting as a vasoconstrictor, thus helping to maintain blood pressure, especially during situations such as significant blood loss. This contributes to the hormone's overall purpose of maintaining body water homeostasis and supporting blood volume and pressure.