Which structure is the site of filtration in the nephron?

Which structure is the site of filtration in the nephron?

• A. Afferent arteriole
• B. Glomerulus
• C. PCT
• D. DCT

Answer: (B)

Filtration in the nephron occurs at the renal corpuscle, specifically across the glomerular capillary wall into Bowman's space. The glomerulus is a tuft of capillaries that blood from the afferent arteriole enters and from which filtrate is produced. The filtration barrier—composed of a fenestrated endothelial lining, the basement membrane, and podocyte foot processes with slit diaphragms—allows water and small solutes to pass while restricting larger proteins and cells. The filtrate then collects in Bowman's capsule and enters the tubule to be processed. Structures like the proximal and distal tubules are involved in reabsorption and secretion after filtration, not in the filtration step itself.

Filtration in the nephron occurs at the renal corpuscle, specifically across the glomerular capillary wall into Bowman's space. The glomerulus is a tuft of capillaries that blood from the afferent arteriole enters and from which filtrate is produced. The filtration barrier—composed of a fenestrated endothelial lining, the basement membrane, and podocyte foot processes with slit diaphragms—allows water and small solutes to pass while restricting larger proteins and cells. The filtrate then collects in Bowman's capsule and enters the tubule to be processed. Structures like the proximal and distal tubules are involved in reabsorption and secretion after filtration, not in the filtration step itself.