QS Study

Aldosterone is produced in the cortex of the adrenal glands, which are located above the kidneys. It is essential for sodium conservation in the kidney, salivary glands, sweat glands, and colon. It affects the body’s ability to regulate blood pressure. It is a steroid hormone synthesized in and secreted from the outer layer of the adrenal cortex, the zona glomerulosa.

Regulation of the aldosterone secretion

Four factors are known as the essential factors which play essential role in the regulation of aldosterone secretion.

(1) Increase (K+) concentration in the ECF: Increased potassium ion concentration in the extracellular fluid greatly increases aldosterone sec.

↑ K+ conc in ECF →↑ Aldosterone secretion.

(2) Increased activity of renin-angiotensin system:

It causes greatly increased aldosterone secretion. Increased activity of the renin-angiotensin system also greatly increases aldosterone secretion. By the action of this hormone, blood pressure rises which inhibits further activity of renin-angiotensin system.

(3) Increased Na+ concentration:

↑ Na+ conc. → slightly ↓ aldosterone secretion. Increased sodium ion concentration in the extracellular fluid very slightly decreases aldosterone secretion.

(4) ACTH:

ACTH from ant. pituitary has little effect on aldosterone sec. ACTH from the anterior pituitary gland is necessary for aldosterone secretion but has little effect in controlling the rate of secretion.

(5) Other stimuli cause ↑ aldosterone secretion:

  • Surgery,
  • Anxiety,
  • Physical trauma,
  • Haemorrhage,
  • Construction of inferior vena cava in the thorax,
  • Standing,
  • Secondary hyperaldosteronism.
  • High K+ intake,
  • Low Na+