Question

How do action potentials travel along the axon?

Answer 1

Hint: Action potentials are produced when an increased energy of the cell membrane to depolarize above the excitation threshold, releasing all sodium ion channels. If the potassium ion channels are activated but sodium ion channels are blocked, when potassium ions exit the cell, the cell membrane remains hyperpolarized; throughout that refractory time, the cell cannot burn.

Complete answer:
Through a chemical known as neurotransmitter, a neuron may obtain feedback from other neurons. The neuron will transfer the signal to downstream neurons if this feedback is powerful enough.
Transmission of the signal inside the neuron is achieved by enclosing the voltage-gated ion channels, allowing the resting membrane potential to be temporarily inverted in order to generate an action potential.

In 4 steps, an action potential occurs:
• Threshold depolarization.
• Sodium channel activation and fast depolarization: sodium ions flood through the cytoplasm as well as the surface of the inner membrane changes between negative to positive.
• Sodium-channel inactivation or potassium-channel activation: Sodium channel inactivation gates shut at +30 mV and potassium channels open, repolarization begins
• Revert back to normal permeability: The potassium channels start to close whenever the membrane enters normal resting potential i.e. -70 mV and the membrane becomes hyperpolarized to -90 mV whenever the potassium channels stop closing.

The potential of the transmembrane then drops to a resting level, and the potential for action is over.
Potentials of action travel down an unmyelinated axon through constant propagation, in which one portion of the axon is influenced by the passing action potential at a time. The next section is depolarized to the threshold by a local current, and the loop repeats, propagating the action potential mostly in 1 direction all along the axon, at a speed of around 1 meter/sec.

Note: Action Potentials are called an all-or nothing" case. The neuron absolutely depolarizes until the threshold potential is attained. The channels of Na+ close, initiating the refractory cycle of the neuron. The voltage-gated K+ channels release at the same time enabling K+ to exit the cell. The membrane potential once again remains negative when K+ ions exit the cell.