1、 Neuron:Supporting cells:CNS:neuroglia(glia)PNS:Schwann cells and satellite cells Functions:physical support electrical insulation metabolic exchange blood-brain barrierComposition of Nervous TissueTypes and Functions of GliaName of Glial CellFunctionAstrocyte(Astroglia)Star-shaped cells that provid
2、e 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 MicrogliaLike astrocytes,microglia digest parts of dead neurons.Oligo-dendrogliaProvide the insulati
3、on(myelin)to neurons in the central nervous system.Satellite CellsPhysical support to neurons in the peripheral nervous system.Schwann CellsProvide the insulation(myelin)to neurons in the peripheral nervous system.Neuroglia in the CNSAble to replicate!Importance in nervous system function is VASTLY
4、underestimated!Evidence is mounting:Nurturing roleSignaling role(Memory?)InflammationPainMany more to e!Neuroglia:Distinguishing FeaturesPresence of tight junctions between the endothelial cellsOne of the notable features of endothelial cells in parison to other cell is the lack of pinocytic vesicle
5、sSelective permeability to molecules based on their molecular weight and lipid solubilityPresence of specific markersRich 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
6、(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 BarriersBBB1.Neurons have TWO processes called axons and dendrites.Glial
7、 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 MOR
8、E(10-50 times more)glial cells in the brain pared to the number of neurons.Glia are different from neurons:Nerve CellsNeurons,Glia,Extracellular Space,and BloodBidirectional Communication Partners in the CNSReceiving signals from neighboring neurons and responding to them with release of neuroactive
9、 substancesExpress receptors for almost all neurotransmitters and neuromodulatorsIncrease of intracellular calcium concentrationMembrane depolarization in astrocytes are mon responses to neural activityMetabolically coupled to neural activityMetabolism of Astrocytes and their Metabolic Cooperation w
10、ith 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
