Which best describes the function of sodium channels in neurons?

Which best describes the function of sodium channels in neurons?

• A. Decrease conduction by hyperpolarization
• B. Transport ions across the membrane
• C. Increase conduction by enabling depolarization
• D. Block action potentials

Answer: (C)

Sodium channels are voltage-gated gates that open in response to the neuron's membrane potential reaching a threshold, allowing Na+ ions to rush into the cell. This inward flow of positive charge depolarizes the membrane, turning negative inside toward positive, which is the rising phase of the action potential. That depolarization is what propagates along the axon, increasing conduction as the electrical signal moves forward. If these channels open conductivity would drop back or hyperpolarization would occur only when the gate is closed or other currents dominate, so opening Na+ channels does the opposite of decreasing conduction or blocking signals. While ion channels do transport ions across the membrane, the key point here is that opening Na+ channels enables depolarization and thus fast, propagated impulses along the neuron.

Sodium channels are voltage-gated gates that open in response to the neuron's membrane potential reaching a threshold, allowing Na+ ions to rush into the cell. This inward flow of positive charge depolarizes the membrane, turning negative inside toward positive, which is the rising phase of the action potential. That depolarization is what propagates along the axon, increasing conduction as the electrical signal moves forward. If these channels open conductivity would drop back or hyperpolarization would occur only when the gate is closed or other currents dominate, so opening Na+ channels does the opposite of decreasing conduction or blocking signals. While ion channels do transport ions across the membrane, the key point here is that opening Na+ channels enables depolarization and thus fast, propagated impulses along the neuron.