神经元和神经细胞-胶质细胞.ppt

Neuron : Supporting cells : CNS : neuroglia (glia) PNS : Schwann cells and satellite cells Functions : physical support electrical insulation metabolic exchange blood-brain barrier Able to replicate! Importance in nervous system function is VASTLY underestimated! Evidence is mounting: Nurturing role Signaling role (Memory?) Inflammation Pain Many more to come! 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 compared to the number of neurons. * 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 Neuroglia: Distinguishing Features Presence of tight junctions between the endothelial cells One of the notable features of endothelial cells in comparison 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 io