Lecture Notes: Neuroglia Cells

Overview

• Neuroglia cells, or glial cells, are the supporting cells for neurons.
• Found in both the peripheral and central nervous systems.

Peripheral Nervous System (PNS)

• Schwann Cells
  • Wrap around axons in the PNS.
  • Responsible for myelination, providing electrical insulation.
  • Participate in repair processes after injury.

Central Nervous System (CNS)

• More diverse in neuroglia types.

Oligodendrocytes

• Function similarly to Schwann cells but located in the CNS.
• Myelinate axons and provide structural framework.
• Found in white matter of the CNS.

Astrocytes

• Maintain the blood-brain barrier.
• Provide structural support and regulate ion, nutrient, and gas concentrations.
• Absorb and recycle neurotransmitters.
• Form scar tissue after injury.
• Found in both white and gray matter.

Microglia

• Phagocytic cells that protect neurons by removing debris and pathogens.
• Present in both white and gray matter.

Ependymal Cells

• Line the ventricles and central canal of the brain and spinal cord.
• Assist in producing, circulating, and monitoring cerebrospinal fluid (CSF).
• Work with capillaries to produce CSF, similar to blood plasma but without cells and proteins.

Nervous Tissue Organization

• Gray Matter

  • Composed of neuron cell bodies, dendrites, and nissl bodies.
  • Site of integration and processing.

• White Matter

  • Contains axons transmitting information.
  • Appears white due to myelinated axons.

Function of Myelination

• Myelin sheath is an insulating layer around axons, aiding in rapid signal transmission.
• Important for both CNS and PNS functioning.
• Not all axons are myelinated; some require slower signal transmission.

Example of Myelination

• In PNS, Schwann cells wrap around axons to form the myelin sheath.
• Not every axon is myelinated due to space constraints and functional needs.

Test Question Example

• Matching neuroglia cells to their functions:
  • Oligodendrocytes: Form myelin sheath in CNS.
  • Astrocytes: Anchor neurons and blood vessels, maintain extracellular environment.
  • Microglia: Defense and phagocytosis in CNS.
  • Schwann Cells: Form myelin sheath in PNS.
  • Ependymal Cells: Ciliated cells forming and circulating CSF.