Schwann cells

Definition

Schwann cells are a type of glial cell found in the peripheral nervous system, responsible for the myelination of neuronal axons. They play a crucial role in the conduction of nerve impulses and in the regeneration of damaged nerves, significantly enhancing the speed at which electrical signals travel along the axon.

5 Must Know Facts For Your Next Test

1. Schwann cells not only create the myelin sheath around axons but also provide structural support and maintenance for peripheral nerves.
2. In addition to myelination, Schwann cells are involved in the repair process after nerve injury, releasing growth factors that promote regeneration.
3. Unlike oligodendrocytes in the central nervous system, each Schwann cell is responsible for myelinating a single segment of one axon.
4. Schwann cells can also form non-myelinating supportive structures around unmyelinated axons, helping to maintain their health.
5. The process of myelination by Schwann cells begins during fetal development and continues into early adulthood, contributing to optimal nerve function.

Review Questions

• How do Schwann cells contribute to nerve impulse conduction in the peripheral nervous system?
  • Schwann cells contribute to nerve impulse conduction by forming the myelin sheath around peripheral axons. This insulation allows electrical impulses to travel more quickly along the axon due to saltatory conduction, where action potentials jump from one node of Ranvier to another. The presence of myelin significantly increases the speed and efficiency of signal transmission, which is vital for proper nervous system function.
• Compare and contrast the roles of Schwann cells and oligodendrocytes in myelination within the nervous system.
  • Both Schwann cells and oligodendrocytes are crucial for myelination, but they operate in different parts of the nervous system. Schwann cells are found in the peripheral nervous system and myelinate individual axons, while oligodendrocytes are located in the central nervous system and can myelinate multiple axons simultaneously. This difference impacts their roles in supporting nerve function and injury recovery, as Schwann cells are particularly adept at facilitating nerve regeneration.
• Evaluate the impact of Schwann cell dysfunction on peripheral nerve health and function.
  • Dysfunction of Schwann cells can lead to significant issues in peripheral nerve health and function, resulting in conditions like Charcot-Marie-Tooth disease or Guillain-Barré syndrome. When Schwann cells fail to properly myelinate axons or respond inadequately to injury, it can hinder nerve impulse conduction and impair sensory and motor functions. This can lead to symptoms such as muscle weakness, numbness, or pain. Understanding these impacts highlights the importance of Schwann cells in maintaining a healthy nervous system.

Related terms

Myelin sheath: A fatty layer produced by Schwann cells that insulates axons and increases the speed of electrical transmission along nerve fibers.

Nodes of Ranvier: Gaps in the myelin sheath where action potentials are regenerated, allowing for faster signal propagation through saltatory conduction.

Oligodendrocytes: Glial cells in the central nervous system that also provide myelination, similar to Schwann cells, but can myelinate multiple axons simultaneously.