Which component insulates the axon to speed conduction?

Which component insulates the axon to speed conduction?

• A. Myelin sheath
• B. Dendrites
• C. Soma
• D. Axon terminals

Answer: (A)

The myelin sheath insulates the axon, speeding conduction. Myelin wraps around the axon from glial cells (oligodendrocytes in the CNS and Schwann cells in the PNS), creating a high-resistance, low-capacitance layer that reduces current leakage. This insulation allows the electrical signal to travel faster and more efficiently because the action potential only needs to be regenerated at the gaps between myelin segments, known as the Nodes of Ranvier. This mode of transmission—saltatory conduction—lets the impulse jump from node to node rather than moving continuously along the entire membrane, dramatically increasing speed. In contrast, dendrites are primarily for receiving inputs, the soma is the cell body that integrates signals, and axon terminals transmit signals to other neurons, but none of these provide the insulating property that boosts conduction speed. Demyelination, as seen in certain diseases, slows conduction and impairs function, highlighting the importance of the myelin sheath in rapid neural communication.

The myelin sheath insulates the axon, speeding conduction. Myelin wraps around the axon from glial cells (oligodendrocytes in the CNS and Schwann cells in the PNS), creating a high-resistance, low-capacitance layer that reduces current leakage. This insulation allows the electrical signal to travel faster and more efficiently because the action potential only needs to be regenerated at the gaps between myelin segments, known as the Nodes of Ranvier. This mode of transmission—saltatory conduction—lets the impulse jump from node to node rather than moving continuously along the entire membrane, dramatically increasing speed. In contrast, dendrites are primarily for receiving inputs, the soma is the cell body that integrates signals, and axon terminals transmit signals to other neurons, but none of these provide the insulating property that boosts conduction speed. Demyelination, as seen in certain diseases, slows conduction and impairs function, highlighting the importance of the myelin sheath in rapid neural communication.