JGA operates a multihormonal Renin-Angiotensin-Aldosterone System (RAAS). The JGA responds to a decrease in blood pressure or blood volume in the afferent arteriole of the glomerulus and releases the hormone renin into the bloodstream. In the blood, renin initiates chemical reactions that convert a plasma protein, called angiotensinogen, to a peptide called angiotensin II, which works as a hormone. Angiotensin II increases blood pressure by causing arterioles to constrict. It also increases blood volume in two ways - firstly, by signalling the proximal convoluted tubules to reabsorb more NaCl and water, and secondly, by stimulating the adrenal gland to release aldosterone, a hormone that induces the distal convoluted tubule to reabsorb more Na+ and water. This leads to an increase in blood volume and pressure, completing the feedback circuit by supporting the release of renin.