Study Notes on Nervous System Cells and Functions

Central Nervous System (CNS)

  • Myelination in the CNS

    • Myelination is provided by specific cells that can myelinate multiple axons simultaneously.
    • This is in contrast to the peripheral nervous system (PNS), where the process differs significantly.

  • Microglial Cells

    • Function: Serve as immune cells within the CNS.
    • Role: They are akin to phagocytes and are responsible for devouring dead material or invading pathogens.
    • Importance: Given the presence of the blood-brain barrier in the CNS, microglial cells provide necessary immune defense that restricts other immune components from entering the CNS.

  • Ependymal Cells

    • Location: These cells align the cavities of the ventricles in the brain.
    • Function: They are involved in the secretion and circulation of cerebrospinal fluid (CSF), essential for cushioning the brain, delivering nutrients, and removing waste.

  • Summary of CNS Neuroglial Cells

    • The CNS contains four main types of neuroglial cells:
      1. Myelinating cells
      2. Microglial cells
      3. Ependymal cells

Peripheral Nervous System (PNS)

  • Neurolemmocytes (Schwann Cells)

    • Function: These neuroglial cells provide myelination specifically for the peripheral nervous system.
    • Characteristics: A singular section of an axon receives myelination from one neurolemmocyte, contrasting that with the CNS where one cell can myelinate multiple axons.

  • Satellite Cells

    • Function: These cells attach to neuron cell bodies to provide structural support and nourishment.

  • Summary of PNS Neuroglial Cells

    • The PNS contains two main types of neuroglial cells:
      1. Neurolemmocytes
      2. Satellite cells

Functions of the Nervous System

  • Common Physiological Responses

    • During various activities of daily life, the body exhibits standard responses such as:
      • Increased heart rate
      • Dilation of pupils
    • These physiological responses enable better visibility and efficiency in various situations encountered in life.

  • Overall Comparison

    • The functions of the different neuroglial cells within both the CNS and PNS illustrate various operational roles in myelination, immune support, and maintain homeostasis across the nervous system.