Antidiuretic hormone:_______A) increases the permeability of the collecting ducts to water.B) is secreted in response to low potassium ion in the blood.C) causes the kidneys to produce a larger volume of very dilute urine.D) is secreted by the anterior pituitary.E) release is insensitive to the osmolarity of interstitial fluid.

Antidiuretic hormone. Hormone released primarily in response to changes in serum osmolarity or blood volume. It causes the kidneys to conserve water by concentrating urine and reducing its volume, stimulating water reabsorption.

The antidiuretic hormone (ADH), or arginine vasopressin (AVP), is a hormone released primarily in response to changes in serum osmolarity or blood volume. Also known as argipressin. It causes the kidneys to conserve water by concentrating urine and reducing its volume, stimulating water reabsorption, increasing the permeability of the collecting tubules for water. It is named after this important function as a homeostatic fluid regulator. It also has functions in the brain and blood vessels. It is a small hormone (oligopeptide) consisting of nine amino acids: NH2-Cys-Tyr-Phe-Gln-Asn-Cys-Pro-Arg-Gly-COOH. Vasopressins are peptide hormones produced in the hypothalamus. Most are stored in the back of the pituitary gland (neurohypophysis) in order to be released into the bloodstream, some of them being released even directly in the brain. Vasopressin is in high concentrations in the locus coeruleus and in the black substance, which are catecholaminergic nuclei.