PHSI 208 Lecture Notes - Lecture 33: Starling Equation, Extracellular Fluid, Hydrostatics
Document Summary
3 types of capillaries: continuous, fenestrated, sinusoidal (discontinuous) Capillary exchange occurs via diffusion (transcellular or paracellular) or transcytosis. Bulk flow = the mass movement of fluid as the result of hydrostatic or osmotic pressure gradients. If bulk flow is resulting in fluid moving into the capillaries, absorption is taking place. Is bulk flow is resulting in the movement of fluid out of capillaries, this is filtration. *pressure pushes fluid out, proteins draw fluid back in. Steady in the capillary and exceeds the interstitial space (zero) Ph in vessels decreases as blood travels through the capillaries due to the resistance encountered and exceeds interstitial ph (zero) At the arterial end, ph exceeds causing net filtration (2/3 of capillary) At the venous end, exceeds ph and there is absorption (1/3 of capillary) Overall there is a net filtration from the entire capillary network resulting in a loss of 3l of fluid/day from the blood.
