When blood pressure decreases, aldosterone is secreted as a result of the <u>renin-angiotensin-aldosterone</u> mechanism
Explanation:
The Renin-angiotensin-aldosterone system is a critical hormone-controlled mechanism which functions to regulate blood pressure, systemic vascular resistance, and fluid electrolyte balance.
Organs involved: Kidneys, systemic vasculature, lungs and brain.
The three main components of this system – renin, angiotensin and aldosterone
Renin, a protelytic enzyme released by kidneys when the blood sodium levels decrease or potassium levels increase, sympathetic nerve action, or hypotension.
Renin activates the conversion of angiotensinogen (in liver) to angiotensin I, a hormone.
The enzyme angiotensin-converting enzyme (ACE) present in the lungs converts angiotensin I to angiotensin II which then constrict the blood vessels to increase the blood pressure.
Angiotensin II triggers the adrenal glands to release aldosterone a hormone which activates the renal tubules to absorb sodium and water to retain the levels, and excrete excess potassium.
When the action of this mechanism increases, the blood pressure will increase.
This is a preventive mechanism and prevents atherosclerotic heart disease by controlling blood pressure which leads to heart failure and also prevents kidney diseases by controlling body fluid and electrolyte balance.
