ABSTRACT
As previously stated, an increase in the osmolarity of plasma or a decrease in blood pressure triggers release of ADH, which in turn causes increased water reabsorption in the kidneys, antidiuresis and a concentrated urine. Similarly, an increase in blood pressure and/or a decrease in the osmolarity of plasma represses ADH release, and causes diuresis with a corresponding drop in blood volume and pressure. Thus, ADH is important in the minute-to-minute control of blood volume and pressure because it is stored by the posterior pituitary, and can be released quickly upon demand. Another important action of ADH occurs in the brain, where it stimulates thirst (like angiotensin II; Ch. 27). Consumption of water will also add fluid to the vascular system, and will thus increase blood pressure.
