What is the cluster of capillaries that Bowman's capsule surrounds in the nephron?

• A. Glomerulus
• B. Loop of Henle
• C. Renal pelvis
• D. Ureter

Answer: (A)

Filtration in the nephron begins at a tuft of capillaries—the glomerulus—that Bowman's capsule surrounds. Blood enters this capillary cluster via the afferent arteriole, passes through fenestrated capillaries, and the filtrate filters into Bowman's space to begin urine formation. Bowman's capsule encases this capillary tuft, forming the initial filtrate collection area. The other structures have different roles: the Loop of Henle concentrates urine as it reabsorbs water and solutes, while the renal pelvis and ureter are part of the urine drainage system, not the capillary network involved in filtration.