BISC 313 Lecture Notes - Lecture 13: Membrane Transport Protein, Fluorouracil, Gastrointestinal Tract
21 Feb 2019
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Pharmacists/pharmacy textbooks define absorption as passing into bloodstream". Prof argues absorption is when a chemical gets into the first layer of the phospholipid bilayer: bilayer acts a barrier to certain chemical, chemical needs to pass thru it to have some toxicological effect. Five ways to pass through membranes: filtration through pores, passive diffusion (most hydrophobic env contaminants move into organisms usually fall into this category, active transport, active transport. Unlike passive diffusion, this can become saturated (zero order process) Eg. fluorouracil -> chemotherapy agent: cancer cells actively divide a lot, you need a lot of nucleobases, like uracil, to make. Dna/rna, if you don"t have those present, cell cant divide. Fluorouracil replaces uracil, and it doesn"t work properly, cell cant divide. Pb2+ looks like calcium (size, charge), cells cant distinguish the two, so pb gets into cell by calcium transport proteins. Eg. occurs in the gastrointestinal tract: eg. glucose, brought in by facilitated diffusion, eg.
