Question

How does the kidney help in maintaining water balance in the body?

Answer 1

Kidney:

1. Kidneys are called chief excretory organs because they play vital roles in blood filtration and urine formation.
2. They also maintain the water balance in the body.

Osmoregulation by kidneys

1. Kidneys carry out reabsorption as the second step of urine formation. Reabsorption checks the water and ion loss and maintains their balance in the body.
2. Antidiuretic hormone or ADH is a hormone secreted by the posterior lobe of the pituitary gland. ADH controls the reabsorption of water by kidney tubules or nephrons. It plays an important role in maintaining water balance in the body.
3. If the body is well hydrated, the blood is diluted. The osmoreceptors in the hypothalamic region of the brain transmit a signal to the pituitary and inhibit ADH secretion. This causes the nephrons of the kidneys to reabsorb less water and this results in the excretion of dilute urine.
4. When the body is dehydrated, the blood gets concentrated. Secretion of ADH is facilitated, which signals the nephrons to reabsorb more water to maintain water balance in the body. This leads to the formation of concentrated urine.