question_answer 23)

  Which one of the following is also known as ant diuretic hormone? (a) Oxytocin                                       (b) Vasopressin                (c) Adrenaline                   (d) Calcitonin

Answer:

Ans. (b) Vasopressin is also known as Antidiuretic Hormone (ADH). It is secreted from the neurohypophysis of pituitary and facilitates water reabsorption from latter parts of the tubule, thereby preventing diuresis. Oxytocin is a mammalian neurohypophysial hormone produced by the hypothalamus and is stored and secreted by the posterior pituitary gland. Oxytocin stimulus contractions of uterus at the end of pregnancy and also contractions of mammary glands the help in flow of milk. Adrenaline is relesed by adrenal medulla at the time of emergency, hence has a role in "fight or flight' reaction. Calcitonin is produced in humans primarily by the parafollicular cells of the thyroid. It acts to reduce blood calcium , level opposing the effect of parathyroid hormone.