Vasopressin hormone is secreted by the posterior pituitary gland. It constricts the blood vessel and increases reabsorption of water from kidney. Hence, it decreases loss of water through urine. Norepinephrine is secreted by adrenal medulla. It increases heart rate and blood pressure. It also increases rate of respiration and alertness. Glucagon hormone is secreted by the alpha cells of Islets of Langerhands. It stimulates glycogenolysis in the liver. It increases amount of glucose in the blood. Prolactin hormone is secreted by the anterior pituitary gland. It promotes the mild formation in females. It also causes growth or enlargement of mammary glands.