The release of aldosterone from the adrenal cortex is activated by

The release of aldosterone from the adrenal cortex is activated by angiotensin II.

Angiotensinogen $\stackrel{\mathrm{Renin}}{\to }$ Angiotensin I

Renin is secreted by the JG cells of the kidney.

Angiotensin I $\stackrel{\mathrm{Angiotensin} \mathrm{converting} \mathrm{enzyme} \left(\mathrm{ACE}\right)}{\to }$Angiotensin II

ACE is secreted by endothelial cells of the lungs.