Total x-sectional area increases, velocity of flow through any one branch decreases. Therefore, flow decreases as x-sectional area increases. Exchange of Material Cross the Capillary wall. Diffusion - Driving force from high to low. Oxygen nutrients CO 2 .
Forces are responsible.
See book for detail. In general Hydrostatic pressure gradient favors filtration. Osmotic gradient favors reabsorption. Net filtration occurs at the arterial end with net absorption occurring at the venous end. Overall there is a small net filtration or loss of protein free fluid from the capillaries.