Overview of Peripheral Nervous System Cells

Neuron Structure and Function

  • Cell Body

    • Also known as the soma or perikaryon.
    • Houses the nucleus and most organelles essential for neuronal function.
    • Serves as the control center for the neuron.

  • Satellite Cells

    • Located around the cell body of peripheral nervous system neurons.
    • Control the chemical environment around neurons in the peripheral nervous system (PNS).
    • Facilitate the exchange of substances between blood and neuron, maintaining homeostasis.

  • Astrocytes

    • Function in the central nervous system (CNS) similar to satellite cells in PNS.
    • Help regulate the chemical environment around neurons, also ensuring nutrient supply and waste removal.

  • Axons and Schwann Cells

    • The axon is the long, slender projection that conducts electrical impulses away from the cell body.
    • Schwann Cells
    • Specialized glial cells in the PNS that produce myelin.
    • Myelination occurs through Schwann cells wrapping around the axon multiple times, forming the myelin sheath.
    • The plasma membrane of Schwann cells makes up the myelin sheath, supporting faster electrical signal transmission along the axon.

Myelin Formation

  • The wrapping process of Schwann cells around an axon can be visualized as a continuous spiral, similar to a snake coiling around an object or a sheet of paper being wrapped tightly.
  • As the Schwann cell wraps around the axon, it squeezes out the cytoplasmic contents and constructs the insulating myelin sheath essential for efficient nerve signal conduction.

Multiple Sclerosis (MS)

  • An autoimmune condition affecting the nervous system.
  • Characterized by damage to myelin in both the central and peripheral nervous systems, leading to varied symptoms.
  • Symptoms may include muscle weakness, coordination issues, and other neurological impairments due to disruption in signal transmission.
  • The variability in symptoms is because MS can affect parts of the nervous system differently, and the extent of myelin damage varies among individuals.