• Structural and functional unit of the nervous system

• Specialized for signal reception, integration, and transmission

Main Parts:

• Cell Body (Soma/Perikaryon):

  • Contains large nucleus with prominent nucleolus

  • Nissl bodies (rER + ribosomes) for protein synthesis

  • Neurofilaments and microtubules for support and transport

• Dendrites:

  • Multiple, branched processes

  • Receive impulses from other neurons

  • Contain same organelles as soma (except Golgi complex)

• Axon:

  • Single long process

  • Originates from axon hillock (no Nissl bodies)

  • May be myelinated (faster conduction) or unmyelinated

  • Ends in axon terminals (synaptic boutons)

• 5. Myelin

  • Concentric layers of lipid-rich membrane around axons

  • Increases conduction velocity (saltatory conduction at nodes of Ranvier)

  • Produced by:

    • Oligodendrocytes in CNS

    • Schwann cells in PNS

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  6. Gray vs. White Matter

  • Gray Matter: Contains neuronal cell bodies, dendrites, unmyelinated axons, glia, synapses

  • White Matter: Contains myelinated axons and glia (no neuronal cell bodies)

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  7. Ganglia

  • Sensory Ganglia (dorsal root, cranial): Pseudounipolar neurons, surrounded by satellite cells

  • Autonomic Ganglia: Multipolar neurons, less organized, surrounded by satellite cells

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Neurons consists of a cell body or soma, multiple dendrites, an axon. and a presynaptic terminal.