Learning Objective: By the end of this lesson, the learner will be able to explain the key physiological functions of aldosterone, including sodium reabsorption, potassium secretion, and extracellular volume regulation, and identify the primary stimuli for aldosterone release in clinical and physiological contexts.
Activity
Aldosterone
Primary Functions
- Sodium reabsorption in principal cells of the distal nephron → increases extracellular volume and indirectly affects blood pressure.
- Potassium secretion in principal cells → regulates plasma potassium levels.
Primary Stimuli for Aldosterone Release
- Plasma Angiotensin II (Ang II) → part of the renin-angiotensin-aldosterone system (RAAS)
- Plasma potassium (K⁺) levels → hyperkalemia directly stimulates aldosterone
Relationship with ADH
- ADH (vasopressin) is mainly regulated by plasma osmolality and blood pressure/volume.
- ADH can also be stimulated by:
- Ang II
- Corticotropin-releasing hormone (CRH) → clinically relevant during stress (surgery, illness)
