The propagation of an action potential (AP) in an unmyelinated axon is called continuous propagation. This activity will test your understanding of the sequence of events that occur during continuous propagation.

Place the following events involved in the propagation of an action potential in the correct order of occurrence from left to right:

A) Voltage Gated Na + channels open

B) Influx of Na+

C) Local current flows to axon segment

D) Axon segment depolarized to threshold

E) AP generated in adjacent axon segment

C, D, A, B, E

Explanation:

The sudden decrease or increase in the potential of cell membrane is Action potential. The stimulus (local current) allows change in the membrane potential, thus allowing depolarization of the membrane. This initiates the opening of Voltage Gated Na + channels. The sodium starts entering the cell that is influx of Na + and thus AP generated in adjacent axon segment. The sodium channels inactivates by membrane repolarization and activated pottassium channels allows the efflux of pottassium ions. The inactivation of potassium channels occurs by hyperpolarization (low membrane potential) brings the membrane to its resting state. Thus, the correct order is C, D, A, B, E.