Learning Objective: By the end of this lesson, the learner will be able to explain the physiological actions of ADH, including water reabsorption and vascular tone regulation, and identify the primary regulators of ADH secretion based on plasma osmolality and blood pressure/volume changes.
Anti-Diuretic Hormone (ADH / AVP) — Key Points
Primary Functions
- Water reabsorption in principal cells of the distal nephron via V2 receptors → regulates extracellular osmolality
- Vasoconstriction via V1 receptors → regulates vascular tone/blood pressure
Primary Regulators of ADH Secretion
- Plasma osmolality (directly related)
- ↑ osmolality → ↑ ADH
- ↓ osmolality → ↓ ADH
- Blood pressure/volume (inversely related)
- ↓ blood pressure/volume → ↑ ADH
- ↑ blood pressure/volume → ↓ ADH
Clinical Relevance
- ADH is critical for water balance
- Disorders:
- SIADH → excess ADH → hyponatremia
- Diabetes insipidus → ADH deficiency/resistance → polyuria and hypernatremia
