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按一下以編輯母片標題樣式,按一下以編輯母片,第二層,第三層,第四層,第五層,*,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,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.,Neuroglia in the CNS,Able to replicate!,Importance in nervous system function is VASTLY underestimated!,Evidence is mounting:,Nurturing role,Signaling role(Memory?),Inflammation,Pain,Many more to e!,Neuroglia:,Distinguishing Features,Presence of tight junctions between the endothelial cells,One of the notable features of endothelial cells in parison 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,BBB,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 pared to the number of neurons.,Glia are different from neurons:,Nerve Cells,Neurons,Glia,Extracellular Space,and Blood,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 mon responses to neural activity,Metabolically coupled to neural activity,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.,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,
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