生理-第二章-细胞的基本功能.ppt

单击此处编辑母版标题样式,*,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,Chapter 2,1.The cell membrane&its transport,Fluid mosaic model,Transport,across cell membrane,*,Simple diffusion,*,Facilitated diffusion,*,Active transport,*,Secondary active transport,*,Exocytosis&endocytosis,BASIC FUNCTIONS OF THE CELL,Fluid mosaic model of membrane,*,Simple diffusion&its energy source,O,2,CO,2,NH,3,NO,etc.,*,Facilitated diffusion&its characteristics,Facilitated diffusion via ion channel,Chemically gated channel,Voltage-gated channel,Mechanically gated channel,Na,+,K,+,Ca,2+,Cl,channel,Facilitated diffusion via carrier,Glucose,amino acids,some ions,etc.,Facilitated diffusion via ion channel,Facilitated diffusion via carrier,*,Active transport,Sodium-potassium pump&its effects,Other pumps:calcium pump,proton pump,*,Secondary active transport,Membrane protein:,pump+transporter,Forms:,symport&antiport,*,Exocytosis&endocytosis,Exocytosis:cell secretion,Endocytosis:phagocytosis,Receptor mediated endocytosis,Sodium-potassium pump,Secondary active transport,2.Transmembrane signal transduction,Concept,Several main forms,*,Mediated by ion channel,*,Mediated by G-protein coupled receptor,*,Mediated by tyrosine kinase receptor,*,Mediated by intercellular channel,*,Mediated by nitric oxide,Cellular proto-oncogene,Mediate-early gene,*,Mediated,by ion channel,Ionotropic receptor,*,Mediated by,G-protein coupled receptor,Metabotropic receptor,G-protein,effecter enzyme,AC,-,cAMP-PKA,PLC-IP,3,-Ca,2+,-CaM&PLC-DG-PKC,G-protein-ion channel,*,Mediated by,tyrosine kinase receptor,Tyrosine kinase receptor,receptor-associated tyrosine kinase,A model of G-protein coupled receptor,G-protein coupled receptor mediated transduction,Tyrosine kinase receptor mediated transduction,3.Bioelectrical phenomena of the cell,Several basic,concepts,*,Excitability,*,Excitable cells or tissues,*,Stimulus&excitation,*,Threshold stimulus,intensity or threshold,*,Relationship between,Excitability&threshold,Bioelectrical phenomena,of nerve&muscle cells,*,Resting potential(RP),*,Action potential(AP),*,Resting potential(RP),A constant potential difference at rest,Between both sides of the membrane,Negative inside relative to outside,70 mV(neuron),90 mV(muscle),*,Action potential(AP),Occurs when a stimulus is applied,A brief deflection(,spike,)of the baseline,Depolarization,&,repolarization,phases,All or none,&not attenuated propagation,Relationship,between,excitation&,AP,Measurement of resting potential(RP),Action,potential,Genesis,of resting potential,*,Differences in the distribution of major ions,between intra-&extra-cellular fluids,*,Variations in membrane permeability to,those ions during rest,*,Outward,diffusion of K,+,E,K,*,Transmembrane diffusion of other ions,*,Electrogenesis of sodium pump,Genesis,of action potential,*,Depolarization phase,Membrane permeability to Na,+,E,Na,Depolarization+overshoot,*,Repolarization phase,Membrane permeability to Na,+,Membrane permeability to K,+,E,m,Repolarization,*,After repolarization(resting phase),Sodium pumps work,recovery,of the distribution of K,+,i,&Na,+,O,Several,physiological,terms,*,Polarization,*,Depolarization,*,Overshoot,*,Repolarization,*,Hyperpolarization,*,Spike&after-potential,Negative&positive after-potential,The,further mechanism,Why does the membrane permeability,change when the cell receives a stimulus?,*,Na,+,channel is voltage dependent,Stimulus,a few Na,+,channels open,membrane depolarizationwhen reached the,firing level,a great amount of,Na,+,channels,open(regenerative cycle),APs burst,*,Na,+,channel has 3 states,Resting,active&inactive states,Three states of Na,+,channel,Experimental evidence,*,Voltage clamp,technique,By Hodgkin&Huxley in 1940,Principle:,G,Na,=1/R,Na,=I,Na,/(E,m,E,Na,),G,K,=1/R,K,=I,K,/(E,m,E,K,),*,Combined with,pharmacological,technique,Na,+,channel blocker:tetrodotoxin(TTX),K,+,channel blocker:tetraethylammonium(TEA),*,Patch clamp,technique,By Neher&Sakmann in 1976,Voltage clamp,Membrane current,Changes of membrane conductance during AP,Patch Clamp,Records with,the technique of,patch clamp,Local response&threshold potential,*,Local response,Definition&Characteristics:,Gradational,electrotonic propagation,summation,(spatial&temporal,),*,Threshold potentialfiring level,Definition,*,Initiation,of action potential,Threshold stimulus or Several subthreshold,stimuli,depolarization,firing level,T,Local response,Local response and its contribution to AP,Conduction,of action potential,Mechanism:,local current,Characteristics:,In both directions,*,Along an unmyelinated fiber,*,Along a myelinated fiber,Saltatory conduction,faster than that along an unmyrlinated fiber,Energy-sparing principle,Conduction of AP along an unmyelinated fiber,Conduction of AP along an myelinated fiber,4.,Contraction of skeletal muscle,Neuromuscular transmission,*,Structure of neuromuscular junction,*,Process of neuromuscular transmission,APs of somatic efferent nerve reach the,terminal,voltage gated Ca,2+,channels,open,Ca,2+,enter the terminalAChs,quantal,release,get across the cleft and then bond,the,N type ACh gated channels,channels,open,more Na,+,enter&fewer K,+,outflow,the muscle cell,endplate potential,APs,Neuromuscular transmission,*,Characteristics,of neuromuscular transmission,Chemically,transmission,One-way,conduction,Temporal,delay,Endplate potential is a,local potential,Neuromuscular transmission is,1,:,1,Easily affected,by internal environmental factors,*,Factors,affecting neuromuscular transmission,Affecting,transmitter release:,Ca,2+,O,Mg,2+,O,Affecting,channel receptor:,tubocurarine,-,bungarotoxin,Affecting,acetylcholinesterase:,organic phosphorus,Excitation-contraction coupling,*,Definition,*,Relative structure:,myotube system,Triad:,L,ongitudinal-,T,ransversal-,L,ongitudinal tubule,*,Coupling factor:Ca,2+,*,Basic process,APs reach the transversal tubule near triad,Signal transmission to,cisterma terminalis,Ca,2+,release&return,Mypfibril,sarcomere&myotube system,Molecular mechanism of contraction,*,Sliding theory,*,Directed proof:,Shortening of muscle only,seen in,light band,&not in,dark band,*,Relative structure:,myofibril,&,sarcomere,Sarcomere:,thick,&,thin filament,Thick filament:,myosin,(contain,cross bridge,),Thin filament:,actin,tropomyosin,troponin,*,Basic process(see the next page),Thick&thin filament,*,Basic process,Ca,2+,i,Ca,2+,bond troponin,troponins conformation changes,tropomyosins conformation changes,binding sites in the actin exposure,cross bridge bond the binding site and,draw thin filament sliding to the midline,muscle shortening,Process of contractionfilament sliding,Forms of muscular contraction,*,Isometric,&,isotonic,contractions,Definition&examples,*,Single twitch,&compound contraction,Compound contraction:,incomplete,&,complete,tetanus,Definition&significance,Single twitch&compound contraction,Factors affecting muscular contraction,*,Preload,Preload&initial length,Length-tension curve,Optimal preload&optimal length,*,Afterload,Tension,onset of shortening delay,velocity,&distance of shortening,Force velocity relation curve,*,Contractility of muscles,Definition&affecting factors,Length-tension curve,Length-tension curve,Force velocity relation curve,