Final answer:
During an action potential propagation, voltage-gated Na+ and K+ ion channels open and close in sequence, resulting in depolarization and repolarization of the neuron's membrane, which allows the action potential to travel along the axon.
Step-by-step explanation:
Propagation of an Action Potential
When an action potential is propagated along an axon, voltage-regulated ion gates open and close in a specific sequence. Initially, electrical stimulation opens voltage-gated sodium channels (Na+ channels), resulting in a rush of Na+ ions into the neuron. This influx of sodium ions causes the membrane potential to rapidly shift from its resting state (approximately -70mV) to a positive value (+30mV), a process known as depolarization. Subsequently, the change in membrane potential triggers the opening of voltage-gated potassium channels (K+ channels), allowing K+ to exit the cell, which ultimately leads to the repolarization of the neuron.
While the potassium channels are open, the sodium channels inactivate, preventing further entry of Na+ ions. As K+ continues to leave the cell, the membrane potential returns to its resting state. Once the resting potential is restored, the potassium channels close, and the sodium channels reset to their closed state, ready to be opened again for the next action potential. This sequential opening and closing of ion channels ensure that the action potential propagates in only one direction along the axon.
The coordinated action between Na+ and K+ channels is essential for the rapid transmission of electrical signals through the nervous system and is crucial for various physiological processes, including muscle contraction and the transmission of sensory information.