1、Cellular NeurobiologyNeuroscience Research InstitutePeking UniversityDepartment of NeurobiologyPeking University Health Science CenterAlbert Cheung-Hoi YU 1One of the Cajals many drawings of Brain circuityThe letters label the different elements Cajal identified in an area of the human cerebral cort
2、ex that controls voluntary movement.2 Neurons:Excitable cells “wiring”“Signal Senders”Neuroglia:Support,Nurturing,InsulationCellular Components3Nerve CellsNeuronsNeuroglia4 Cell body(soma;perikaryon)Axon:only one(branches are collaterals;terminals are end feet)Dendrites:much shorter;one or more than
3、 one;branch extensively into dendritic treesStructure of NeuronsAxon Hillock(Axonal end feet)5The Axon and Axon Collaterals6 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 cel
4、l body receive messagesNeurons Structure&Function7 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 NucleolusMicrofilaments/NeurotubulesEndopla
5、smic Reticulum(ER)Mitochondria Golgi ApparatusNissl BodiesOthers8 Dendrites:dendrite tree Axon:axon hillock(axon origination)axonal transport system initial segment(first myelin sheath)action potential generation myelin sheath Axon and Dendrites9AxonsDendritesTake information away from the cell body
6、Take information to the cell bodySmooth surfaceRough surface(dendritic spines)Generally only 1 axon per cellUsually many dendrites per cellNo ribosomeHave ribosomesCan have myelinNo myelin insulationBranch further from the cell bodyBranch near the cell bodyDifferences between Axons and Dendrites10Ne
7、uron Classification by ShapeMultipolar:“multi-”many processesMajority: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(dor
8、sal root ganglia)11Classification of Neurons by Morphology12Classification of Neurons by Axon Length1.Golgi type I NeuronsLong axons(longest from the cortex to the tip of spinal cord,50-70 cm)2.Golgi type II NeuronsShort axons(shortest axons terminate only a few micron from cell body,interneurons)3.
9、Amacrine NeuronsAn unusual cell type,lack axons13Sensory neuron from receptor to CNS;receive stimuli and transmit afferent impulses to CNSInterneurons communicating between neurons;form circuits in the CNSMotor neuron from CNS to effector cells;deliver efferent impulses out through the PNS to the ef
10、fectors to carry out the actions directed by the CNSFunctional Classification of Neuron14 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 Neurons15Action Potential16
11、Four Functional Regions of Model Neurons17 Impulse transmission:electrical chemical Morphology:axodendritic axonsomatic axoaxonic dendrodendriticClassification of Synapses18synapse4Vesicles release Neurotransmitters19 Chemical synapse:presynaptic knob(presynaptic component)synaptic vesicles synaptic
12、 cleft postsynaptic membrane(postsynaptic component)Electrical synapse:gap junctionsSynapse Structures2021 Types of synapseDis-tanceCytoplasmic continuityUltrastruct-ural componentAgent of trans-missionSynaptic delayDirection of trans-missionElectrical3.5 nmYesGap-junction channelIon currentVirtuall
13、y absentUsually bidirectionalChemical20-40 nmNoPresynaptic vesicle and active zone;postsynaptic receptorsChemical transmittersSignificant:at least 0.3 ms;usually 1-5 ms or longerUni-directional Distinguishing Properties of Electrical and Chemical Synapses22At a chemical synapse,neurons transmit info
14、rmation across a cleft.231.Small Molecule Neurotransmitter SubstancesAcetylcholine(ACh);Dopamine(DA);Norepinephrine(NE);Serotonin(5-HT);Histamine2.Amino AcidsGamma-aminobutyric acid(GABA);Glycine;Glutamate;Aspartate3.Neuroactive Peptides-partial list!Bradykinin;beta-endorphin;calcitonin;cholecystoki
15、nin;enkephalin;dynorphin;insulin;gastrin;substance P;glucagon;secretin;vasopressin;oxytocin,etc.List of Some Neurotransmitters24 Axonal transport:intracellular communication Bidirectional mechanism:anterograde transport retrograde transport Classified by transport rates:slow transport system(0.2 to
16、1 mm/day)fast transport system(200 to 400 mm/day)Axonal Transport Systems25Hitching a Ride on“Retrorail”26Membranes of organelles involved in synaptic transmission are returned to the cell body for reuse or degradationNucleusCytoskeleton(Anterograde transport)2728ComponentRate(mm/day)Structure and c
17、ompositionFast transport Anterograde 200-400Small vesiculotubular structures,neurotransmitters;membrane proteins and lipidsMitochondria50-100MitochondriaRetrograde 200-300Lysosomal vesicles and enzymesSlow transport SCb2-8Microfilaments,metabolic enzymes,clathrin complexSCa0.2-1Neurofilaments and microtubulesMajor Rate Components of Axonal Transport29写在最后写在最后成功的基础在于好的学习习惯成功的基础在于好的学习习惯The foundation of success lies in good habits30谢谢大家荣幸这一路，与你同行ItS An Honor To Walk With You All The Way讲师：XXXXXX XX年XX月XX日
