[临床医学]神经生物学概述神经元.ppt

* * Blood Brain Barrier * * 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. Glia are different from neurons: * * * * 1.支持作用：星状胶质细胞--支架 2.修复和保护作用：(Astroglia, Oligodendrocyte) 3.物质代谢和营养性作用： 蛋白质、糖原→血管周足→神经元胞体 4.绝缘和屏障作用： 施万细胞Schwann’s cell, 少突胶质细胞(Oligodendrocyte) 5.维持合适的离子浓度： Astroglia上的钠-钾泵的作用 6.摄取和分泌神经递质： Schwann’s cell可以分泌ACh, 能摄取γ -氨基丁酸 Functions of Neuroglia * * 　　神经细胞能够感受到刺激和传导兴奋，是构成神经系统的结构和功能的基本单位，又称为神经元。 　　CNS中大约有1000亿个神经元。传入和传出为 3:1 。一个神经元可以与上万个其它神经元构成联系，形成了极为复杂的网络系统。 * 　　神经元作为基本功能单位是因为：独立发育而成；有高电阻分界面分隔；有明显的边界；动作电位传递以神经元为界。 * Light micrograph showing the ependymal lining of the central canal of the spinal cord. A diagrammatic view of the neural tissue in the CNS showing relationships between neuroglia and neurons. * The role of glia cells: Glial cells support neurons, providing the brain with structure, they also separate and sometimes insulate neuronal groups and synaptic connections from each other. Two types of glial cells (oligodendrocytes and Schwann cells) produce the myelin used to insulate nerve cell axons, the cell outgrowths that conduct electrical signals. Some glial a scavengers, removing debris after injury or neuronal death. Glial cells perform important housekeeping chores that promote efficient signaling between neurons.some glia also take up chemical transmitters released by neurons during synaptic transmission. During brain development certain classes of glial cells (radial glia) guide migrating neurons and direct the outgrowth of axons. In some cases, as at the nerve-muscle synapse 1921年，德国科学家勒维（O．Loewi）进行了一个著名的“蛙心交叉灌流实验”。蛙的心脏受