Final answer:
The renin-angiotensin-aldosterone system is a hormone system that helps regulate blood pressure and fluid balance in the body. It consists of several hormones and enzymes that work together in a chain reaction to maintain these vital functions.
Step-by-step explanation:
The renin-angiotensin-aldosterone system is a hormone system that helps regulate blood pressure and fluid balance in the body. It consists of several hormones and enzymes that work together in a chain reaction to maintain these vital functions.
The process begins when specialized cells in the kidneys secrete the enzyme renin in response to low blood volume or low blood pressure. Renin converts the blood protein angiotensinogen, produced by the liver, into the hormone angiotensin I. Angiotensin I is then converted into angiotensin II in the lungs by the enzyme angiotensin-converting enzyme (ACE).
Angiotensin II has three major functions: it raises blood pressure by constricting blood vessels, triggers the release of the hormone aldosterone from the adrenal cortex which stimulates the reabsorption of sodium by the kidneys, and stimulates the release of anti-diuretic hormone (ADH) from the hypothalamus, leading to water retention in the kidneys.