- Triggers for Renin Release
- ↓ BP: Detected by juxtaglomerular (JG) cells in the afferent arteriole.
- ↓ Na+ delivery: Detected by macula densa cells in the distal convoluted tubule (DCT).
- ↑ Sympathetic tone: β1-adrenergic receptor stimulation of JG cells.
- Pathway/Cascade
- Renin (secreted by JG cells in kidney) converts angiotensinogen (from liver) → angiotensin I.
- Angiotensin-converting enzyme (ACE) (primarily in lung capillary endothelium) converts angiotensin I → angiotensin II.
- Hemodynamic Efficiency: The lungs are the only organ that receives 100% of the cardiac output (right ventricle output).
- ACE is also responsible for the breakdown of bradykinin (a vasodilator).