MICROANATOMY

Detailed explanation-1: -The primary osmoreceptors that control AVP secretion and thirst are located in the anterior hypothalamus.

Detailed explanation-2: -Osmoreceptors in the hypothalamus signal the posterior pituitary gland to increase ADH secretion when plasma osmolarity becomes too high. ADH causes decreased urine volume and decreased plasma osmolarity.

Detailed explanation-3: -Clearly supraoptic neurones respond directly to changes in the osmolarity of their immediate environment. Since these cells also control the rate of secretion of vasopressin they contribute to osmoreception.

Detailed explanation-4: -A basic example is that a decrease in water concentration of blood is detected by osmoreceptors in hypothalamus, which stimulates ADH release from pituitary gland to increase the permeability of the wall of the collecting ducts and tubules in the nephrons.