What is the importance of osmoregulation 1


English: osmoregulation

1 definition

As Osmoregulation is the term used to describe the homeostasis of the osmolality of the plasma, which is primarily achieved by a control circuit that connects the posterior pituitary gland with the kidney.

2 physiology

During osmoregulation, the HHL releases the hormone ADH (also adiuretin, vasopressin) in a positive relationship to the plasma osmolality. Through V2-receptor-mediated stimulation of water reabsorption in the distal tubules and collecting ducts of the kidney, ADH lowers the osmolality again, thereby closing the control loop. In addition, ADH also stimulates V1 receptors, which have a vasoconstrictor effect and thus increase blood pressure, and V3 receptors, which in turn increase ACTH secretion in the anterior pituitary.

3 Clinic and Pathophysiology

Important symptoms of osmoregulation are central diabetes insipidus (point a in the diagram), in which ADH secretion from the pituitary gland fails to occur, and renal diabetes insipidus (point b in the diagram), which is caused by resistance to ADH, e.g. B. is characterized in a mutation of the V2 receptor or in certain diseases of the kidney.

Schwartz-Bartter syndrome (SIADH) is characterized by a pathologically increased secretion of ADH with a consecutive retention of water and a loss of sodium (hyponatremia).

The function of the control loop can be checked using the following examination procedures: