AP BIOLOGY

Detailed explanation-1: -As ADH (which is also known as vasopressin) causes direct water reabsorption from the kidney tubules, salts and wastes are concentrated in what will eventually be excreted as urine. The hypothalamus controls the mechanisms of ADH secretion, either by regulating blood volume or the concentration of water in the blood.

Detailed explanation-2: -An osmoreceptor is a sensory receptor that detects changes in osmotic pressure and is primarily found in the hypothalamus of most homeothermic organisms. Osmoreceptors detect changes in plasma osmolarity (that is, the concentration of solutes dissolved in the blood).

Detailed explanation-3: -ADH is stored in neurons within the hypothalamus. These neurons express osmoreceptors that are exquisitely responsive to blood osmolarity and respond to changes as little as two mOsm/L. [2] Therefore, slight elevations in osmolarity result in the secretion of ADH.

Detailed explanation-4: -Osmoregulation and Thirst. Osmolality of body fluids is monitored by hypothalamic osmoreceptors, which regulate both water intake (thirst) and renal conservation of water through adjustments in the rate of ADH secretion (see Chapter 9).