Which of the following substances crosses capillary walls primarily through water-filled clefts between the endothelial cells?
O2
CO2
CO
Glucose
Because O2, CO2 and CO are lipophilic, they cross capillary walls primarily by diffusion through the endothelial cell membranes. Glucose is water soluble; it cannot cross through the lipid component of the cell membrane and is restricted to the water-filled clefts, or pores, between the cells.
Transpo Processes