Most Small Molecules Pass Through a Capillary Wall Through Which

Question

Most small molecules pass through a capillary wall through which route?
A) via direct diffusion through the endothelium
B) via pinocytotic vesicles
C) through intercellular clefts
D) through tight junctions

Accepted Answer

Small molecules like oxygen, carbon dioxide, and water can diffuse through the intercellular clefts between the endothelial cells of capillaries. Large molecules like proteins, on the other hand, cannot pass through this route and must use alternative mechanisms like pinocytosis or transcytosis. Tight junctions and direct diffusion through the endothelium are not significant routes for small molecule transport through capillaries.