复旦生理学课件01生物膜对物质的通透和转运

第一篇细胞生理学第一章生物膜的物质转运功能第二章细胞的兴奋第三章细胞间信息传递第四章肌细胞的收缩功能第一章生物膜的物质转运功能fromBerne&LevyPrinciplesofPhysiology(4thed)2005Chap.1CellularMembranesandTrans-membraneTransportofSolutesandWater•Cellmembraneservesasapermeabilitybarrierthatallowsthecelltomaintainacytoplasmiccompositionfardifferentfromthecompositionoftheextracellularfluid.•Themembranesthatenclosethevariousorganellesdividethecellintodiscretecompartmentsandallowthelocalizationofparticularbiochemicalprocessesinspecificorganelles.Singer流动镶嵌模型SimpleDiffusionviacarriersFacilitatedDiffusion•Saturation:astheconcentrationofthetransportedcompoundisincreased,therateoftransportatfirstincreases,buteventuallyaconcentrationsreachedafterwhichthetransportrateincreasesnofurther.•Specificity:onlymoleculeswiththerequisitechemicalstructurearetransported.•Competitiveinhibition:structurallyrelatedmoleculesmaycompetefortransport.waterchannelionchannels叶公杼和詹裕农Shaker钾通道•Ionicselectivity:•Activation:voltage-gated,ligand-gated,mechanosensitiveorbackgroundcurrentchannel•离子通道的随机活动•primaryactivetransporthasadirectlinktometabolicenergy,viapumps.ActiveTransport•secondaryactivetransportderivesenergyfromtheconcentrationgradientofanothersubstancethatisactivelytransported,viasymporterorantiporter(exchanger).钠钾泵细胞的钙转运系统EndocytosisandExocytosisreceptormediatedendocytosisphagocytosisfluidphaseendocytosis•simplediffusion•primaryactivetransport•endocytosis&exocytosis•facilitateddiffusionporesionchannelscarriers•secondaryactivetransportsymportantiportpassiveactiveacrossthrough