Final answer:
Antidiuretic hormone (ADH) contributes to homeostasis by regulating the amount of water reabsorbed by the kidneys. Negative feedback controls ADH levels by inhibiting its release when blood osmolality or volume return to normal.
Step-by-step explanation:
Antidiuretic hormone (ADH) is an example of how a hormone contributes to homeostasis and is regulated by negative feedback. ADH, also known as vasopressin, regulates water balance in the body by controlling the amount of water reabsorbed by the kidneys. When there is an increase in blood osmolality or a decrease in blood volume, ADH is released from the posterior pituitary gland and acts on the kidneys to increase water reabsorption. This helps maintain the balance of body fluids and prevents dehydration.
The release of ADH is controlled by negative feedback. When blood osmolality or blood volume returns to normal, the release of ADH is inhibited. For example, if a person is dehydrated and blood osmolality increases, ADH is released to conserve water. As the person rehydrates and blood osmolality decreases, the release of ADH is inhibited, preventing excessive water retention.