What is the renal artery?

• A. A vein that drains blood from the kidney.
• B. Blood vessel that carries blood to the kidney to be filtered through the glomerulus.
• C. A nerve supplying the kidney.
• D. A capillary network that surrounds Bowman's capsule.

Answer: (B)

The renal artery is the main vessel that delivers blood into the kidney so it can be filtered in the glomeruli. Arteries carry blood away from the heart, and the renal artery enters the kidney and branches into smaller arteries and arterioles that feed the glomeruli, the sites where filtration begins. It is not a vein (which would drain blood from the kidney), not a nerve (which transmits signals), and not a capillary network around Bowman's capsule (that network is the glomerulus itself). The artery’s role is to supply high-pressure blood for filtration, with blood eventually leaving the kidney through the renal vein.