Afferent arteriole

The afferent arterioles are a group of blood vessels that supply the nephrons in many excretory systems. They play an important role in the regulation of blood pressure.

The afferent arterioles branch from the renal artery which supplies blood to the kidneys.

The afferent arterioles later diverge into the capillaries of the glomerulus.

When renal blood flow is reduced (indicating hypotension), the macula densa releases prostaglandins, which cause the juxtaglomerular cells lining the afferent arterioles to release renin, activating the renin-angiotensin-aldosterone system, to increase blood pressure.