Neuroglial Cells

Terminology

  • Nerve: A group of axons wrapped together in connective tissue, found only in the peripheral nervous system.
  • Ganglia: Collections of neuron cell bodies grouped together in masses, also found in the peripheral nervous system.

Neuroglial Cells

  • Support cells for neurons, crucial for protecting neuron health and longevity.

Neuroglial Cells of the Peripheral Nervous System

  • Schwann Cells:
    • Composed of a fatty myelin sheath.
    • Wrap around axons to insulate and protect them.
    • Increase the speed of nerve impulses.

Node of Ranvier

  • Gaps between Schwann cells along the axon.
  • Enable saltatory conduction, where electrical impulses jump from one node to the next.
  • Saltatory conduction is much faster than the electrical signal traveling the entire length of the axon.

Neuroglial Cells of the Central Nervous System

  • Ependymal Cells:

    • Circulate cerebrospinal fluid (CSF).
    • Cerebrospinal fluid:
      • Specialized clear fluid found in the brain and spinal cord.
      • Protects the brain and spinal cord.
      • Enables the brain to float, preventing it from hitting the skull.
    • Allow fluid exchange between the brain, spinal cord, and cerebrospinal fluid, acting as a filtering system.

  • Oligodendrocytes:

    • Provide insulation for central nervous system axons, similar to Schwann cells in the PNS.
    • One oligodendrocyte can cover multiple neurons.

  • Astrocytes:

    • Control the chemical environment of neurons.
    • Wrap around blood capillaries, creating a blood-brain barrier.
    • The blood-brain barrier restricts the passage of certain substances into the brain, protecting the central nervous system.

  • Microglial Cells:

    • Protect the central nervous system by phagocytizing dead cells and pathogens.
    • Act as immune cells in the brain and spinal cord.

Overview of Neuroglial Cells in the CNS

  • Capillaries provide blood supply.
  • Astrocytes wrap capillaries, forming the blood-brain barrier.
  • Oligodendrocytes wrap around axons for insulation.
  • Microglia clean up dead cells.
  • Ependymal cells circulate cerebrospinal fluid.