Myelin Sheath

Definition

The myelin sheath is a protective fatty layer that surrounds the axons of certain nerve cells, known as myelinated neurons. It acts as an insulator, enhancing the speed and efficiency of electrical impulse transmission along the neuron.

5 Must Know Facts For Your Next Test

1. The myelin sheath is composed of lipids and proteins, which provide insulation and allow for faster propagation of electrical signals.
2. Oligodendrocytes in the central nervous system and Schwann cells in the peripheral nervous system are responsible for producing and maintaining the myelin sheath.
3. The myelin sheath is not continuous along the length of the axon, but rather has periodic gaps called nodes of Ranvier.
4. Saltatory conduction, where the electrical impulse 'jumps' from one node of Ranvier to the next, allows for faster and more efficient transmission of signals.
5. Damage or degeneration of the myelin sheath can lead to neurological disorders, such as multiple sclerosis, where the impaired signal transmission causes various symptoms.

Review Questions

• Explain the role of the myelin sheath in the transmission of electrical impulses along a neuron.
  • The myelin sheath plays a crucial role in the efficient transmission of electrical impulses along a neuron. By acting as an insulator, the myelin sheath increases the speed of signal propagation through a process called saltatory conduction. In this process, the electrical impulse 'jumps' from one node of Ranvier to the next, allowing for faster and more energy-efficient transmission compared to continuous conduction along an unmyelinated axon.
• Describe the relationship between the myelin sheath and the types of cells responsible for its production and maintenance.
  • The myelin sheath is produced and maintained by specialized glial cells. In the central nervous system, oligodendrocytes are responsible for myelinating axons, while in the peripheral nervous system, Schwann cells perform this function. These cells wrap their plasma membrane multiple times around the axon, forming the insulating myelin sheath. The close relationship between the myelin sheath and these supporting glial cells is essential for the proper functioning and health of the nervous system.
• Analyze the potential consequences of damage or degeneration of the myelin sheath and how this can lead to neurological disorders.
  • Damage or degeneration of the myelin sheath can have severe consequences for the proper functioning of the nervous system. When the myelin sheath is compromised, the efficient transmission of electrical impulses along the affected axons is disrupted, leading to various neurological symptoms and disorders. One such example is multiple sclerosis, a chronic autoimmune disease in which the immune system attacks and damages the myelin sheath. This impairs signal transmission and can result in a wide range of neurological problems, such as muscle weakness, sensory disturbances, cognitive impairments, and even paralysis. Understanding the critical role of the myelin sheath in neural communication is essential for comprehending the underlying mechanisms and potential treatments for these debilitating neurological conditions.

Related terms

Axon: The long, slender projection of a neuron that transmits electrical impulses away from the cell body to other neurons or target cells.

Oligodendrocyte: A type of glial cell in the central nervous system that produces and maintains the myelin sheath around axons.

Saltatory Conduction: The rapid transmission of electrical impulses along myelinated axons, where the impulse 'jumps' from one node of Ranvier to the next.