The 'Hormone Antidiuretic Hormone' (ADH), also known as vasopressin, is synthesized in the hypothalamus and stored in the posterior pituitary. Its primary action in the kidney is to: MCQ with Answer and Explanation

Antidiuretic Hormone (ADH), or vasopressin, is released from the posterior pituitary in response to high blood osmolarity (dehydration) or low blood volume. Its primary action is on the kidneys, specifically the late distal convoluted tubules and the collecting ducts. ADH binds to V2 receptors on the basolateral membrane of the principal cells, triggering the insertion of aquaporin-2 water channels into the apical membrane. This makes the tubule highly permeable to water, increasing water reabsorption from the filtrate back into the blood, producing concentrated urine and conserving body water.