BIOL 2420 Lecture Notes - Lecture 11: Oncotic Pressure, Distal Convoluted Tubule, Afferent Arterioles

• School: University of Manitoba
• Department: Biological Sciences
• Course: BIOL 2420
• Professor: W.G.Anderson

Document Summary

Urine formation begins with glomerular ltration, which occurs at the interface between the glomerulus and bowman"s capsule. Glomerular capillaries ow into bowman"s capsule, forming a 3-layer ltration barrier". These three layers regulate what ends up in the bowman"s capsule: a single layer of porous endothelial capillary cells - largely unregulated. > 100x more permeable than normal capillaries. Pores allow most substances, except large proteins, platelets and blood cells, to pass (these stay in the lumen of the capillary: an acellular gelatinous glycoprotein/collagen layer termed the glomerular basement membrane. Glycoproteins are negatively charged, thus repelling many small plasma proteins, but not the much smaller negative charged ions - ie. cl- and hco3- Keep owing due to opposing forces - hydrostatic pressure (blood pressure) is forcing them through the pores: a third layer of specialized endothelial tubule cells (podocytes) that encircle (wrap themselves around) the glomerular capillaries. End result: complete extracellular ltration of near protein-free uid that is isosmotic with the plasma.