PSL301H1 Lecture Notes - Lecture 12: Vascular Resistance, Basal Lamina, Transcytosis

• School: UTSG
• Department: Physiology
• Course: PSL301H1
• Professor: Christine Wong

Document Summary

Continuous capillaries: continuous epithelium with few breaks, tightly joined: in muscle, connective tissue, neural tissue, impermeable basement membrane, transcytosis vesicles/small pores for movement. Fenestrated capillaries: leaky, allow high volumes to pass through fenestrations/pores: in kidney, intestine, allow larger molecules through basement membrane. Sinusoid: fenestrated capillary with larger than normal window: in bone marrow, liver, spleen, fenestrations and gaps for blood cells and plasma proteins to enter blood. Paracellular pathway: exchange between plasma/interstitium by endothelial movement. Endothelial transport: exchange between plasma/interstitium by movement through cells: small solutes/gases move between cells through cell-cell junctions, diffusion, large solutes/proteins move by vesicular transcytosis via apical/basolateral membranes, velocity dependent on cross-sectional area of all capillaries. Bulk flow: mass movement of fluid as a result of hydrostatic/osmotic pressure gradients. Capillary hydrostatic pressure (pc): forces fluid outward through capillary membrane decreases along length of capillary due to friction. Interstitial fluid pressure (pif): opposes filtration at + value, forces filtration at - value very low, essentially zero.