MICROANATOMY

Detailed explanation-1: -ADH is secreted by pituitary gland. It increases the water permeability of distal convoluted tubules and collecting tubules, hence, plays a significant role in water re-absorption. The absence of ADH will reduce water reabsorption which may lead to water diuresis or diabetes insipidus.

Detailed explanation-2: -During states of increased plasma osmolality, ADH secretion is increased. ADH acts through a G-protein coupled receptor to increase the transcription and insertion of Aquaporin–2 channels to the apical membrane of the DCT and CD cells. Consequently, the permeability of the DCT and CD cells to water increases.

Detailed explanation-3: -ADH increases the permeability to water of the distal convoluted tubule and collecting duct, which are normally impermeable to water. This effect causes increased water reabsorption and retention and decreases the volume of urine produced relative to its ion content.