医学英语-中枢神经系统.ppt

医学英医学英语 中枢神中枢神经系系统One way to classify neurons is by the One way to classify neurons is by the number of extensionsnumber of extensions that extend from the that extend from the neurons cell body(soma).neurons cell body(soma).Bipolar neuronsBipolar neurons have two have two processes extending from processes extending from the cell body(examples:the cell body(examples:retinal cells,olfactory retinal cells,olfactory epithelium cells).epithelium cells).Pseudo-uni-polar cellsPseudo-uni-polar cells (example:dorsal root ganglion(example:dorsal root ganglion cells).Actually,these cells have 2 cells).Actually,these cells have 2 axons rather than an axon and axons rather than an axon and dendrite.One axon extends dendrite.One axon extends centrally toward the spinal cord,centrally toward the spinal cord,the other axon extends toward the other axon extends toward the skin or muscle.the skin or muscle.Multipolar neuronsMultipolar neurons have have many processes that extend many processes that extend from the cell body.However,from the cell body.However,each neuron has only one each neuron has only one axon(examples:spinal axon(examples:spinal motor neurons,pyramidal motor neurons,pyramidal neurons,Purkinje cells).neurons,Purkinje cells).Types of neurons.Types of neurons.第二页，共12页。Neurons can also be classified by the direction that they send information:Sensory(or afferent)neurons:Sensory(or afferent)neurons:send send information from sensory receptors(e.g.,information from sensory receptors(e.g.,in skin,eyes,nose,tongue,ears)in skin,eyes,nose,tongue,ears)TOWARDTOWARD the central nervous system.the central nervous system.Motor(or efferent)neurons:send send information information AWAYAWAY from the central nervous from the central nervous system to muscles or glands.system to muscles or glands.Interneurons:Interneurons:send information send information between between sensory neuronssensory neurons and and motor neuronsmotor neurons.Most.Most interneurons are located in the central interneurons are located in the central nervous system.nervous system.Types of neurons.Types of neurons.第三页，共12页。A single neuron consist of:A single neuron consist of:CELL BODYCELL BODY:is the metabolic center of the neuron,:is the metabolic center of the neuron,contains the Nucleus and Mitochondrion.contains the Nucleus and Mitochondrion.DENDRITESDENDRITES:convey incoming messages to the:convey incoming messages to the cell body.cell body.AXON HILLOCKAXON HILLOCK:a cone like region from where an:a cone like region from where an axon arises.axon arises.AXONSAXONS:generates nerve impulses and topically:generates nerve impulses and topically conduct them away from the cell body.A nerve is a conduct them away from the cell body.A nerve is a group of axons”.group of axons”.Presynaptic terminals:Presynaptic terminals:The swollen,distal end of The swollen,distal end of an axon;contains a neurotransmitter substance an axon;contains a neurotransmitter substance within synaptic vesicles.Also called synaptic within synaptic vesicles.Also called synaptic ending.ending.第四页，共12页。AxonsAxons Take information away from Take information away from the cell body the cell body Smooth Surface Smooth Surface Generally only 1 axon per cell Generally only 1 axon per cell No ribosomes No ribosomes Can have myelin Can have myelin Branch further from the cell bodyBranch further from the cell body DendritesDendritesn nBring information to the cell Bring information to the cell body body n nRough Surface(dendritic Rough Surface(dendritic spines)spines)n nUsually many dendrites Usually many dendrites per cell per cell n nHave ribosomes Have ribosomes n nNo No myelin insulationmyelin insulation n nBranch near the cell bodyBranch near the cell bodyThere are several differences between axons and dendrites:There are several differences between axons and dendrites:第五页，共12页。NEUROGLIAL cells-there are six types of supporting cells;four in the CNS and two in the PNS第六页，共12页。第七页，共12页。第八页，共12页。第九页，共12页。第十页，共12页。The Meninges and Cerebrospinal Fluid第十一页，共12页。第十二页，共12页。谢谢观赏谢谢观赏教学资料整理仅供参考，