北大神经生物学2神经元和神经胶质细胞-神经元PPT参考课件.ppt

Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,Cellular Neurobiology,Neuroscience Research Institute,Peking University,Department of Neurobiology,Peking University Health Science Center,Albert Cheung-Hoi YU,于常海,北京大學神經科學研究所,achy,1,One of the Cajals many drawings of Brain circuity,The letters label the different elements Cajal identified in an area of the human cerebral cortex that controls voluntary movement.,2,Neurons:,Excitable cells,“,wiring,”,“,Signal Senders,”,Neuroglia:,Support,Nurturing,Insulation,Cellular Components,3,Nerve Cells,Neurons,Neuroglia,4,Cell body(soma;perikaryon),Axon:only one(branches are collaterals;terminals are end feet),Dendrites:much shorter;one or more than one;branch extensively into dendritic trees,Structure of Neurons,Axon Hillock,(,Axonal end feet),5,The Axon and Axon Collaterals,6,Cell Body(Soma),:,Life Support,Protein Synthesis,Single Nucleus,RER,(Nissl,Bodies),Axon:,Longest process transmits messages away from cell body,Dendrites:,Multiple processes off cell body,receive messages,Neurons,Structure&Function,7,Neurons are similar to other cells in the body in some ways such as:,1.Neurons are surrounded by a membrane.,2.Neurons have a nucleus that contains genes.,3.Neurons contain:,What are inside of a neuron?,Nucleus,Nucleolus,Microfilaments/Neurotubules,Endoplasmic Reticulum(ER)Mitochondria Golgi Apparatus,Nissl Bodies,Others,8,Dendrites:,dendrite tree,Axon:,axon hillock(axon origination),axonal transport system,initial segment(first myelin sheath),action potential generation,myelin sheath,Axon and Dendrites,9,Axons,Dendrites,Take information away from the cell body,Take information to the cell body,Smooth surface,Rough surface(dendritic spines),Generally only 1 axon per cell,Usually many dendrites per cell,No ribosome,Have ribosomes,Can have myelin,No myelin insulation,Branch further from the cell body,Branch near the cell body,Differences between Axons and Dendrites,10,Neuron Classification by Shape,Multipolar,:,“,multi-,”,many processes,Majority:Single axon,many dendrites(,motor neuron and interneuron),Bipolar,:,“,bi-,”,2 processes,Found in some sensory organs(,retina,taste,smell,inner ear neuron),Unipolar,(,pseudo-unipolar),:,“,uni-,”,1 process(with branches),Sensory afferent neurons,(dorsal root ganglia,),11,Classification of Neurons by Morphology,12,Classification of Neurons,by Axon Length,Golgi type I Neurons,Long axons(longest from the cortex to the tip of spinal cord,50-70 cm),Golgi type II Neurons,Short axons(shortest axons terminate only a few micron from cell body,interneurons),Amacrine Neurons,An unusual cell type,lack axons,13,Sensory neuron,from receptor to CNS;receive stimuli and transmit,afferent,impulses to CNS,Interneurons,communicating between neurons;form circuits in the CNS,Motor neuron,from CNS to effector cells;deliver,efferent,impulses out through the PNS to the effectors to carry out the actions directed by the CNS,Functional Classification of Neuron,14,EXCITABLE Membrane,:Able to regulate the movement of ions(charges)across and along membrane,SIGNAL TRANSDUCTION,DO NOT Replicate,:Damaged cells cannot be replaced!,Important Features,of,Neurons,15,Action Potential,16,Four Functional Regions of Model Neurons,17,Impulse transmission:,electrical,chemical,Morphology:,axodendritic,axonsomatic,axoaxonic,dendrodendritic,Classification of Synapses,18,synapse,4,Vesicles release Neurotransmitters,19,Chemical synapse:,presynaptic knob(presynaptic,component),synaptic vesicles,synaptic cleft,postsynaptic membrane(postsynaptic component),Electrical synapse:,gap junctions,Synapse Structures,20,21,Types of synapse,Dis,-tance,Cytoplasmic continuity,Ultrastruct-ural component,Agent of trans-mission,Synaptic delay,Direction of trans-mission,Electrical,3.5,nm,Yes,Gap-junction channel,Ion current,Virtually absent,Usually bidirectional,Chemical,20-40,nm,No,Presynaptic vesicle and active zone;postsynaptic receptors,Chemical transmitters,Significant:at least 0.3 ms;usually 1-5 ms or longer,Uni-directional,Distinguishing Properties of Electrical and Chemical Synapses,22,At a chemical synapse,neurons transmit information across a cleft.,23,Small Molecule Neurotransmitter Substances,Acetylcholine(ACh);Dopamine(DA);Norepinephrine(NE);Serotonin,(5-HT);Histamine,Amino Acids,Gamma-,aminobutyric acid(GABA);Glycine;Glutamate;,Aspartate,Neuroactive,Peptides-partial list!,Bradykinin;beta-endorphin;calcitonin;cholecystokinin;enkephalin;dynorphin;insulin;gastrin;substance P;glucagon;secretin;vasopressin;oxytocin,etc,.,List of Some Neurotransmitters,24,Axonal transport:,intracellular communication,Bidirectional mechanism:,anterograde,transport,retrograde transport,Classified by transport rates:,slow transport system(0.2 to 1 mm/day),fast transport system(200 to 400 mm/day),Axonal Transport Systems,25,Hitching a,Ride on,“Retrorail”,26,Membranes of organelles involved in synaptic transmission are returned to the cell body for reuse or degradation,Nucleus,Cytoskeleton,(Anterograde transport),27,28,Component,Rate(mm/day),Structure and composition,Fast transport,Anterograde,200-400,Small vesiculotubular structures,neurotransmitters;membrane proteins and lipids,Mitochondria,50-100,Mitochondria,Retrograde,200-300,Lysosomal vesicles and enzymes,Slow transport,SCb,2-8,Microfilaments,metabolic enzymes,clathrin complex,SCa,0.2-1,Neurofilaments and microtubules,Major Rate Components of Axonal Transport,29,1.,Neurons have specialized projections called dendrites and axons.Dendrites take information to the cell body and axons take information away from the cell body,2.Neurons communicate with each other through an electrochemical process,3.Neurons contain some specialized structures(like synapses)and chemicals(like neurotransmitters),4.Nissl Bodies,5.DO NOT Replicate,:,Damaged cells cannot be replaced!,Neurons differ from Other Cells,30,Neuron:,Supporting cells,:,CNS:neuroglia(glia),PNS:Schwann cells and satellite cells,Functions:,physical support,electrical insulation,metabolic exchange,blood-brain barrier,Composition of Nervous Tissue,31,Types and Functions of Glia,Name of Glial Cell,Function,Astrocyte(Astroglia),Star-shaped cells that provide physical and nutritional support for neurons:1)clean up braindebris;2)transport nutrients to neurons;3)hold neurons in place;4)digest parts of dead neurons;5)regulate content of extracellular space,Microglia,Like astrocytes,microglia digest parts of dead neurons.,Oligo-dendroglia,Provide the insulation(myelin)to neurons in the central nervous system.,Satellite Cells,Physical support to neurons in the peripheral nervous system.,Schwann Cells,Provide the insulation(myelin)to neurons in the peripheral nervous system.,32,Neuroglia in the CNS,33,Able to replicate!,Importance in nervous system function is VASTLY underestimated!,Evidence is mounting:,Nurturing role,Signaling role(Memory?),Inflammation,Pain,Many more to come!,Neuroglia:,Distinguishing Features,34,Presence of tight junctions between the endothelial cells,One of the notable features of endothelial cells in comparison to other cell is the lack of pinocytic vesicles,Selective permeability to molecules based on their molecular weight and lipid solubility,Presence of specific markers,Rich in two enzymes:,gamma glutamyl transpeptidase(GGTP)(for amino acid transport)and alkaline phosphatase(transport of phsopahte ions)used as marker for BBB.,Others:,glucose transporter(GLUT-1);endothelial barrier antigen(EBA;unknown function)and antigen recognized by the MRC OX-47 monoclonal antibody(important for cell-to-cell adhesion);transferrin receptor(transport of ferric ions).,Properties of Blood Brain Barriers,35,BBB,36,1.Neurons have,TWO,processes called axons and dendrites.Glial cells only have,ONE,.,2.Neurons,CAN,generate action potentials.Glial cells,CANNOT,however,do have a resting potential.,3.Neurons,HAVE,synapses that use neurotransmitters.Glial cells do,NOT,have chemical synapses.,4.Neurons do,NOT,continue to divide.Glial cells,DO,continue to divide.,5.There are many,MORE,(10-50 times more)glial cells in the brain compared to the number of neurons.,Glia are different from neurons:,37,Nerve Cells,38,Neurons,Glia,Extracellular Space,and Blood,39,Bidirectional Communication Partners,in the CNS,Receiving signals from neighboring neurons and responding to them with release of neuroactive substances,Express receptors for almost all neurotransmitters and neuromodulators,Increase of intracellular calcium concentration,Membrane depolarization in astrocytes are common responses to neural activity,Metabolically coupled to neural activity,40,Metabolism of Astrocytes and their Metabolic Cooperation with Neurons,Glucose,Amino acid metabolism,Enzymes:,glutamine synthetase(glutamate-glutamine cycle);,glycogen phosphorylatase(glycogen mobilization);,pyruvate carboxylase(anaplerotic synthesis of oxaloacetate);,cysteine sulfinate decarboxylase(synthesis of taurine);,glycine cleavage system,glycine metabolism.,41,Three Types of Metabolic Cooperation of Astrocytes and Neurons,Supply of the energy substrate lactate to neurons,The recycling of neuronal glutamate by the glutamate-glutamine cycle,The supply by astrocytes of precursors for neuronal glutathione(GSH)synthesis,42,