苏州大学医学部基础医学与生物科学学院生理学课件 第十四讲.pptVIP

chapter 2 fundamental functions of the cell content 1、substance transport through cell membrane 2、transmembrane signal transduction of cell 3、bioelectrical activity of cell 4、contraction of skeletal muscle §1、 cell membrane plasma membrane function: acts as a barrier and limits transmembrane movement for most of the molecules inside and outside of the cell organelle can maintain normal function signal transduction and transmembrane transport 一、Fabric and function fluid mosaic model ——The cell membrane is composed of two layers of lipids (fat) in which protein molecules are embedded. Lipid bilayer： element： phospholipid ＞70% cholesterol ＜30% sphingolipid（鞘脂） the water-loving (hydrophilic) ends of the lipids face either the exterior or interior of the cell ； the water-hating (hydrophobic) ends of the lipid face the interior of the membrane 。 amphilic molecule（双嗜性分子） influencing factor of the fluidity content of the cholesterol 胆固醇的含量增高，降低膜的流动性； length of the fatty acids 脂肪酸烃链的长度短，膜的流动性增加； unsaturated fatty acid 脂肪酸不饱和度高，膜的流动性增加； content of the protein 膜蛋白多，膜的流动性降低； protein： peripheral protein（表面蛋白质） 20%--30% integral protein（整合蛋白质） 70%--80% glucose： content： 2%-10% combine：glycoprotein、glycolipid distributing：the exterior of the cell function： Attach cells one to another Acts as receptor substance for binding hormone such as insulin Participate in immune reaction as antigen 二、transmembrane transport lipid-soluble molecules move across cell membranes without assistance because of the lipid composition and molecular organization of the cell membrane many molecules cannot cross without assistance (nonlipid-soluble molecules ). the cell membrane is said to be selectively permeable or semipermeable. categories of transport Mechanisms to transport molecules and ions through the cell membrane: non-carrier mediated transport. simple diffusion. facilitated diffusion: via carrier and channel. Voltage, Chemical and M