神经元和神经胶质细胞神经元课件

1、Cellular NeurobiologyNeuroscience Research InstitutePeking UniversityDepartment of NeurobiologyPeking University Health Science CenterAlbert Cheung-Hoi YU 1Cellular NeurobiologyNeuroscieOne of the Cajals many drawings of Brain circuityThe letters label the different elements Cajal identified in an a

2、rea of the human cerebral cortex that controls voluntary movement.2One of the Cajals many drawinNeurons: Excitable cells “wiring” “Signal Senders”Neuroglia: Support, Nurturing, InsulationCellular Components3Neurons: Excitable cells “wiNerve CellsNeuronsNeuroglia4Nerve CellsNeuronsNeuroglia4Cell body

3、 (soma; perikaryon) Axon : only one (branches are collaterals; terminals are end feet)Dendrites : much shorter; one or more than one; branch extensively into dendritic treesStructure of NeuronsAxon Hillock(Axonal end feet)5Cell body (soma; perikaryon) SThe Axon and Axon Collaterals6The Axon and Axon

4、 Collaterals6Cell Body (Soma): Life SupportProtein SynthesisSingle Nucleus, RER (Nissl Bodies)Axon: Longest process transmits messages away from cell bodyDendrites: Multiple processes off cell body receive messagesNeurons Structure & Function7Cell Body (Soma): Life Support Neurons are similar to oth

5、er 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/NeurotubulesEndoplasmic Reticulum (ER) Mitochondria Golgi ApparatusNissl BodiesOthers8 Ne

6、urons are similar to othDendrites :dendrite treeAxon :axon hillock (axon origination)axonal transport systeminitial segment (first myelin sheath)action potential generationmyelin sheath Axon and Dendrites9Dendrites :Axon and Dendrites9AxonsDendritesTake information away from the cell bodyTake inform

7、ation 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 Dendrites10AxonsDendrit

8、esTake informationNeuron 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

9、branches)Sensory afferent neurons (dorsal root ganglia)11Neuron Classification by ShapeClassification of Neurons by Morphology12Classification of Neurons by MClassification of Neurons by Axon LengthGolgi type I NeuronsLong axons (longest from the cortex to the tip of spinal cord, 50-70 cm)Golgi type

10、 II NeuronsShort axons (shortest axons terminate only a few micron from cell body, interneurons)Amacrine NeuronsAn unusual cell type, lack axons13Classification of Neurons GolgSensory neuron from receptor to CNS; receive stimuli and transmit afferent impulses to CNSInterneurons communicating between

11、 neurons; form circuits in the CNSMotor neuron from CNS to effector cells; deliver efferent impulses out through the PNS to the effectors to carry out the actions directed by the CNSFunctional Classification of Neuron14Sensory neuron Functional ClasEXCITABLE Membrane: Able to regulate the movement o

12、f ions (charges) across and along membrane SIGNAL TRANSDUCTIONDO NOT Replicate: Damaged cells cannot be replaced!Important Features of Neurons15EXCITABLE Membrane: Able to reAction Potential16Action Potential16Four Functional Regions of Model Neurons17Four Functional Regions of MoImpulse transmissio

13、n : electrical chemical Morphology : axodendriticaxonsomaticaxoaxonicdendrodendriticClassification of Synapses18Impulse transmission : Classifsynapse4Vesicles release Neurotransmitters19synapse4Vesicles release NeuroChemical synapse :presynaptic knob (presynaptic component)synaptic vesiclessynaptic

14、cleftpostsynaptic membrane (postsynaptic component)Electrical synapse :gap junctionsSynapse Structures20Chemical synapse :Synapse Stru2121Types of synapseDis-tanceCytoplasmic continuityUltrastruct-ural componentAgent of trans-missionSynaptic delayDirection of trans-missionElectrical3.5 nmYesGap-junc

15、tion channelIon currentVirtually absentUsually bidirectionalChemical20-40 nmNoPresynaptic vesicle and active zone; postsynaptic receptorsChemical transmittersSignificant: at least 0.3 ms; usually 1-5 ms or longerUni-directionalDistinguishing Properties of Electrical and Chemical Synapses22Types of s

16、ynapseDis-tanceCytAt a chemical synapse, neurons transmit information across a cleft.23At a chemical synapse, neurons Small Molecule Neurotransmitter SubstancesAcetylcholine (ACh); Dopamine (DA); Norepinephrine (NE); Serotonin (5-HT); Histamine Amino AcidsGamma-aminobutyric acid (GABA); Glycine; Glu

17、tamate; AspartateNeuroactive Peptides - partial list!Bradykinin; beta-endorphin; calcitonin; cholecystokinin; enkephalin; dynorphin; insulin; gastrin; substance P; glucagon; secretin; vasopressin; oxytocin, etc. List of Some Neurotransmitters24 Small Molecule NeurotransmittAxonal transport : intrace

18、llular communicationBidirectional 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 Systems25Axonal transport : Axonal TranHitching a Ride on “Retrorail”26Hitching a 26Membranes of organelles involved in synaptic transmission are returned to the cell body for reuse or degradationNucleusCytoskeleton(Anterograde transport)27Membran