Schwann cell

Definition

A Schwann cell is a type of glial cell that forms the myelin sheath around the axons of peripheral neurons, crucial for efficient signal transmission in the nervous system. These cells not only provide insulation to the axons, enhancing the speed of nerve impulses, but they also play a role in the regeneration of damaged nerves, making them essential for proper neuronal function and repair.

5 Must Know Facts For Your Next Test

1. Schwann cells are derived from neural crest cells during embryonic development and are unique to the peripheral nervous system.
2. They can regenerate after injury, unlike many central nervous system cells, which is vital for healing and regrowth of nerves.
3. Each Schwann cell wraps around a single axon, but multiple Schwann cells are needed to myelinate longer axons.
4. In addition to myelination, Schwann cells also provide metabolic support to neurons and aid in the maintenance of the axonal environment.
5. Dysfunction or damage to Schwann cells can lead to conditions like Guillain-Barré syndrome, where peripheral nerves become demyelinated.

Review Questions

• How do Schwann cells contribute to the speed of nerve impulse transmission?
  • Schwann cells contribute to faster nerve impulse transmission by forming the myelin sheath around peripheral axons. The myelin acts as insulation, preventing ion leakage and allowing action potentials to jump between nodes of Ranvier in a process known as saltatory conduction. This significantly increases the speed at which electrical signals travel along the nerve.
• Discuss the role of Schwann cells in nerve regeneration after injury.
  • Schwann cells play a critical role in nerve regeneration following injury by promoting axonal growth and guiding regrowth. After an injury, Schwann cells undergo changes that allow them to clear debris from damaged neurons and secrete growth factors that encourage the regrowth of axons. They also create a supportive environment that helps direct new axon paths towards their target tissues.
• Evaluate the implications of Schwann cell dysfunction in peripheral nervous system disorders.
  • Dysfunction of Schwann cells can lead to severe consequences in peripheral nervous system disorders, such as demyelinating diseases like Guillain-Barré syndrome or Charcot-Marie-Tooth disease. These conditions can result in symptoms ranging from muscle weakness to sensory loss, severely impacting quality of life. Understanding how Schwann cells function and their role in health and disease provides insights into potential therapeutic approaches for these disorders.

Related terms

Myelin: A fatty substance that surrounds and insulates axons, produced by Schwann cells in the peripheral nervous system and oligodendrocytes in the central nervous system.

Node of Ranvier: Gaps in the myelin sheath between Schwann cells where ion channels are concentrated, facilitating rapid signal conduction via saltatory conduction.

Neurolemmocyte: Another name for Schwann cells, emphasizing their role in forming the myelin sheath and supporting peripheral nerve fibers.