WELCOMETOHumanPhysiology(LECTURESESSION)Department of PhysiologyYangzhou University School of MedicineSpring2020
WELCOME TO Human Physiology (LECTURE SESSION) Department of Physiology Yangzhou University School of Medicine Spring 2020
Chapter2BasicFunctionsofCells-Membrane Structureand MembraneTransport-SignalTransduction--MembranePotential--MuscleCell Contraction
Chapter 2 Basic Functions of Cells - Membrane Structure and Membrane Transport - Signal Transduction - Membrane Potential - Muscle Cell Contraction
CellMembraneStructure55%Proteins25%Phospholipids13%Cholesterol4%Otherlipids3%CarbohydratescarbohydrateEndoplasmicchainretcuumcholesterolFreeribosotRiboscmeMaochondria(dots)CalNuheulphospholipidmembranebilayerProteinmoleculeglycoproteinhydrophilichydrophobicregonsregion
Cell Membrane Structure Proteins 55% Phospholipids 25% Cholesterol 13% Other lipids 4% Carbohydrates 3%
CrossCellMembraneTransport1.SimpleDiffusionCarrierFacilitated Diffusion(noATPneeded)Channel2.Protein-mediatedPrimaryActive Transport(ATPdependent)Secondary3.Vesicle-mediated:Endocytosis/ExocytosisFacilitateddiffusionActiveSimpleChannelCarrierFoodparticleEnvironmentTransporterDiffusionTransporterTransportertakeninbyendocytosisNatGlucoseNaOExocytosisofwasteFoodProductsofparticlesCdigesteddigestionFusionformssecondaryATPK+ADP+PNat2GlucoselysosomeNaPassiveActive
Cross Cell Membrane Transport 1. Simple Diffusion 2. Protein-mediated Facilitated Diffusion (no ATP needed) Active Transport (ATP dependent) Carrier Channel Primary Secondary 3. Vesicle-mediated: Endocytosis/Exocytosis Passive Active Facilitated diffusion
OsmosisIsotonic:Solute concentrationsare equal inside and out.CellsmaintainPlaceinhypotonicnormalOsmosissolution.shape.-SemipermbeableOsmosisisthemovementofwater(reddots)throughasemipermeablemembranemcmbranetoahigherconcentration ofsolutes(blueHypotonicsolution:dots).SoluteconcentrationPlace inis lower outside thehypertonicWater easily moves through cellcell.solution.membranesbyosmosis.HighLowSoluteSoluteCellsswell andHypertonic solution:may even ruptureSolute concentrationbecause waterisis higher outside thetaken into the cell.cell.Cellsshrinkbecausewater exitsthe cell
Osmosis
WhatisElectrochemicalgradientconcentration differenceElectrochemicalgradientelectricaldifference(membranepotential)GramicidinNetOchargeNetchargeElectrochemicalgradientforHighLowsodiumions.(Na")concentrationconcentrationof Nat0ofNa*
What is Electrochemical gradient concentration difference + electrical difference (membrane potential) Electrochemical gradient
Active TransportActiveTransport:"uphill",againstelectrochemicalgradient,ATP-dependent(carriertransporter)OutsideInsideNa+-K+-ATPase3Na3 Na bind to sites exposed insideThebindingofNatstimulatesPhosphorylation exposes the Nathe cell.ATP-dependent phosphorylationbinding sites to the cell surface(Na+-K+Pump)ofthepumpand lowers their binding afinityso that Na is releasedoutsidethe cell.3Natout2K+in2KAtthesametime,2KbindtoThebindingofKstimulatesThe pump thon returnsto itshigh-affinitysitos-egposedonthedephosphorylation of the pump.original conformation,releasingcell surtace.K* inside the cell
Active Transport Active Transport: “uphill”, against electrochemical gradient, ATP-dependent (carrier transporter) Na+ -K + -ATPase (Na+ -K + Pump) 3 Na+ out 2 K+ in
SecondaryActiveTransportSymporterExtracellularGlucosefluidAntiporterNa'-glucoseNaExtracellularspace9symporttransporterreleasingglucosetothecyloplasm00Sodium2Na'-glucosepotassiumsymporAminoAcidpumpcreatesIntracellularspacetransporterion gradientiondingglucosefromECFCytoplasmPene
Secondary Active Transport Symporter Antiporter
EndocytosisvsExocytosisEndocytosisinAnimalCellsExocytosisFigurecellmembranetransportvesiclc.oExtracellularFluid-1releasedcesolublo.ptotoinnReceptorO.PseudopodiumconstitutivesolublounregulatedPlasmasecretionproteinsOmembranefusionOMembraneReceptorcol membraneMediatedproteinsEndocytosissccretoryvesicleFood-PinocytosisCoatedsecreted proteinsPitCoatPhagocytosisProteinregulatedregulatedsecretionesecrotorymembranefusionprotcingreceptorFoodVesicleCoatedVacuoleVesiclesignal transductionGolg apparatusIgand
Endocytosis vs Exocytosis
GrowthFactorReceptorSignal TransductionshemokinesHormonesSignaltransductionoccurswhenanTransmittersGrowthFactaralEactExdracellda(.g,IGF)t.g,neoar(ea.TGFa,ECFMatrixotonin,etc)extracellularsignalingmolecule activatesaGPCRcellsurfacereceptor.lnturn,thisreceptoRTRTKWnFnsiealters intracellularmolecules creating aGn20sPNDishevelledProlelresponse.[1] Therearetwostages inthis5AdenytatedgnhesdasMEprocess:KMFAMAPKNBFacrean 15uo-calenteg,EPCSTATE,01.AsignalingmoleculeactivatesaMadERKJNKSBeatenin:TCFBd-dMaspecificreceptorproteinonthecellCytodhroineC1-p1Rb-CDKAmembrane.D1Gene Regulation2.AsecondmessengertransmitstheCORE-p2ApoptosisAPF021Cellsignal intothecell,elicitingaProliferationBd-2physiologicalresponse.nihtado(eo.FasLiTnt)
Signal Transduction