Final answer:
ADH is released from the posterior pituitary in response to a decrease in blood volume and blood pressure. It causes vasoconstriction and increases water reabsorption in the kidneys, helping to restore vascular volume and increase blood pressure.
Step-by-step explanation:
ADH (antidiuretic hormone), also known as vasopressin, is released from the posterior pituitary in response to a decrease in blood volume and a drop in blood pressure. When blood volume decreases by 5-10%, ADH is released, leading to vasoconstriction and increased water reabsorption in the kidneys. This helps to restore vascular volume and increase blood pressure.