Physiology 3140A Lecture Notes - Lecture 6: Alanine, Sglt2, Exocytosis

• School: Western University
• Department: Physiology
• Course: Physiology 3140A
• Professor: John Di Guglielmo

Document Summary

Cells bound tightly together into sheets called epithelia. Derived from all 3 germ layers: ectoderm epidermis, endoderm gastrointestinal tract, mesoderm inner lining of body cavity. Found in two major types: simple and stratified: shape of cell, number of cells, and shape of nucleus defines type. *note: one organ can contain multiple types of epithelium. Found in organs like the intestine and kidney. Transcellular absorption: molecules must get through apical and basolateral membranes (involves protein carriers/channels) Barrier function (allows selective movement of molecules) Increased surface area (microvilli: increases efficiency of absorption. Avascular: cells do not connect to bloodstream themselves. Diffusion: down concentration gradient, passive transport, small, hydrophobic molecules (hydrophilic molecules need channels) Facilitated diffusion: down concentration gradient (passive, uses protein carrier (protein mediated, no energy (atp) required, specific, limited capacity (can be saturated, can be competitively inhibited. Secondary active transport: similar to facilitated diffusion except: one molecule moves down its concentration gradient to drive another molecule against its concentration gradient (active)