The myelinated segment of an axon that is covered by a glial cell is called a/an ________; the gaps between glial cells where the axolemma is exposed are called ________.

Verified step by step guidance

1. Understand the structure of a myelinated axon: Myelination is the process where glial cells wrap around the axon to form a myelin sheath, which insulates the axon and speeds up nerve impulse conduction.
2. Identify the glial cells involved: In the central nervous system (CNS), oligodendrocytes are responsible for myelination, while in the peripheral nervous system (PNS), Schwann cells perform this function.
3. Define the term for the myelinated segment: The segment of the axon that is covered by the myelin sheath formed by a glial cell is called an internode.
4. Define the term for the gaps: The small gaps between adjacent glial cells where the axolemma (the plasma membrane of the axon) is exposed are called nodes of Ranvier.
5. Summarize the relationship: The internodes are the myelinated segments of the axon, while the nodes of Ranvier are the unmyelinated gaps that play a critical role in saltatory conduction, allowing the nerve impulse to jump from node to node for faster transmission.

Key Concepts

Myelinated Axon

A myelinated axon is a type of nerve fiber that is insulated by a myelin sheath, which is formed by glial cells. This insulation allows for faster transmission of electrical impulses along the axon, enhancing the efficiency of neural communication. The myelination occurs in segments, with gaps known as nodes of Ranvier, where the axon membrane is exposed.

Glial Cells

Glial cells are non-neuronal cells in the nervous system that provide support, protection, and insulation for neurons. In the context of myelination, oligodendrocytes in the central nervous system and Schwann cells in the peripheral nervous system are responsible for forming the myelin sheath around axons. These cells play a crucial role in maintaining the health and functionality of neurons.

Nodes of Ranvier

Nodes of Ranvier are small gaps in the myelin sheath of myelinated axons where the axolemma, or the axon's membrane, is exposed. These nodes are critical for the process of saltatory conduction, where electrical impulses jump from one node to the next, significantly speeding up signal transmission. This mechanism is essential for efficient communication within the nervous system.