Which gland secretes antidiuretic hormone? a. pituitary b. pancreas c. adrenal d. thyroid
The Correct Answer and Explanation is:
The correct answer is a. pituitary.
The pituitary gland, specifically the posterior pituitary (also known as the neurohypophysis), secretes antidiuretic hormone (ADH), which is also known as vasopressin. ADH plays a critical role in the body’s water balance and osmoregulation.
ADH’s main function is to regulate the amount of water reabsorbed by the kidneys. When the body becomes dehydrated or when blood osmolality (the concentration of solutes in the blood) rises, the hypothalamus detects this change and signals the posterior pituitary to release ADH. This hormone acts on the kidneys, specifically the distal convoluted tubules and the collecting ducts, to increase water reabsorption. The reabsorbed water then returns to the bloodstream, helping to dilute the blood and restore proper hydration levels.
This process helps to concentrate the urine, preventing excessive water loss, and plays a crucial role in maintaining homeostasis. When ADH levels are low, the kidneys excrete more water, leading to diluted urine. On the other hand, high levels of ADH result in more concentrated urine and reduced water loss.
Additionally, ADH can cause vasoconstriction, which increases blood pressure, hence the name vasopressin. This is particularly important in situations where blood pressure needs to be regulated.
The other glands listed (pancreas, adrenal, and thyroid) have different roles:
- The pancreas secretes insulin and glucagon, which regulate blood sugar.
- The adrenal glands secrete hormones like adrenaline (epinephrine) and aldosterone, which help control stress responses and sodium balance, respectively.
- The thyroid gland produces hormones like thyroxine (T4) and triiodothyronine (T3) that regulate metabolism.
Thus, the pituitary gland is the primary source of ADH secretion.
