{"id":177,"date":"2023-02-17T22:37:12","date_gmt":"2023-02-17T22:37:12","guid":{"rendered":"https:\/\/content.one.lumenlearning.com\/introductiontopsychology\/chapter\/cells-of-the-nervous-system\/"},"modified":"2025-11-04T16:09:50","modified_gmt":"2025-11-04T16:09:50","slug":"cells-of-the-nervous-system","status":"publish","type":"chapter","link":"https:\/\/content.one.lumenlearning.com\/introductiontopsychology\/chapter\/cells-of-the-nervous-system\/","title":{"raw":"The Nervous System: Learn It 2\u2014Neuron Structure","rendered":"The Nervous System: Learn It 2\u2014Neuron Structure"},"content":{"raw":"
\r\n

Neuron Structure<\/h2>\r\n
\r\n

neuron structure<\/h3>\r\n
\r\n

Neurons are the basic building blocks of the nervous system<\/strong>\u2014about 86 billion<\/strong> at birth. Like all cells, they have specialized parts that allow them to process and transmit information.<\/p>\r\n

    \r\n\t
  • \r\n

    Cell membrane:<\/strong> The neuron\u2019s outer surface is semipermeable<\/strong>, meaning it allows small, uncharged molecules to pass through while blocking larger or charged ones.<\/p>\r\n<\/li>\r\n\t

  • \r\n

    Soma (cell body):<\/strong> Contains the nucleus<\/strong>, which holds the cell\u2019s genetic material and keeps the neuron functioning.<\/p>\r\n<\/li>\r\n\t

  • \r\n

    Dendrites:<\/strong> Branching extensions that receive incoming signals<\/strong> from other neurons.<\/p>\r\n<\/li>\r\n<\/ul>\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"487\"]\"An Figure 1<\/strong>. This illustration shows a prototypical neuron, which is being myelinated by a glial cell.[\/caption]\r\n<\/section>\r\n

    Signal Transmission<\/h4>\r\n
      \r\n\t
    • \r\n

      Axon:<\/strong> A long fiber that carries electrical signals away from the soma. It ends in axon terminals<\/strong> (also called terminal buttons).<\/p>\r\n<\/li>\r\n\t

    • \r\n

      Synaptic vesicles:<\/strong> Found inside the terminals; they store and release neurotransmitters<\/strong>, the chemical messengers<\/strong> of the nervous system.<\/p>\r\n<\/li>\r\n\t

    • \r\n

      Myelin sheath:<\/strong> A fatty layer produced by glial cells that insulates the axon and speeds up signal transmission.<\/p>\r\n<\/li>\r\n\t

    • \r\n

      Nodes of Ranvier:<\/strong> Small gaps in the myelin sheath that allow the electrical signal to \u201cjump\u201d from node to node for faster communication.<\/p>\r\n

        \r\n\t
      • \r\n

        Demyelination:<\/strong> Loss of myelin, as seen in multiple sclerosis (MS), slows neural communication and can cause fatigue, vision problems, and poor coordination.<\/p>\r\n<\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ul>\r\n

        Neural Communication<\/h4>\r\n
          \r\n\t
        • \r\n

          When an electrical impulse reaches the axon terminal, neurotransmitters are released into the synaptic cleft, or gap,<\/strong>\u2014the tiny gap between neurons.<\/p>\r\n<\/li>\r\n\t

        • \r\n

          These molecules cross the cleft and bind to receptors on the dendrites of the next neuron.<\/p>\r\n<\/li>\r\n<\/ul>\r\n<\/section>\r\n

          This video shows the structure and physiology of a neuron.