Which nephron component is primarily responsible for filtration?

Which nephron component is primarily responsible for filtration?

• A. Proximal tubule
• B. Glomerulus
• C. Distal convoluted tubule
• D. Loop of Henle

Answer: (B)

Filtration of plasma into the nephron happens at the glomerulus, where blood is forced through fenestrated capillaries and the filtration barrier into Bowman's capsule. This barrier—composed of endothelial pores, the basement membrane, and podocyte slit diaphragms—allows water and small solutes to pass while keeping cells and large proteins behind. The proximal tubule, loop of Henle, and distal convoluted tubule then modify that filtrate through reabsorption and secretion, but the initial filtration step is performed by the glomerulus.

Filtration of plasma into the nephron happens at the glomerulus, where blood is forced through fenestrated capillaries and the filtration barrier into Bowman's capsule. This barrier—composed of endothelial pores, the basement membrane, and podocyte slit diaphragms—allows water and small solutes to pass while keeping cells and large proteins behind. The proximal tubule, loop of Henle, and distal convoluted tubule then modify that filtrate through reabsorption and secretion, but the initial filtration step is performed by the glomerulus.