The main action of antidiuretic hormone is

Decreases water reabsorption, dilutes urine, increases urine output; constricts blood vessels, raises blood pressure. ADH is secreted by the pituitary gland. There are receptors in the body that sense changes in plasma volume and plasma osmolality. When the blood volume increases and the osmotic pressure decreases, it will cause a feedback reduction in the secretion of antidiuretic hormone. At this time, the renal tubules feel the decrease in ADH level, so they will reduce the reabsorption of water, so that the urine will be diluted and the urine volume will increase. This is one of its main functions. The second function is to contract smooth muscle and raise blood pressure. Under normal circumstances, the human body's blood pressure regulation of antidiuretic hormone and participation is not obvious, but in a large number of fluid loss, such as vomiting, severe diarrhea, as well as blood loss, a large number of sweating, antidiuretic hormone secretion increased, there is appropriate contraction of blood vessels, the role of raising blood pressure.