Question

What is the most correct description of the propagation of action potentials?

-The action potential is reproduced again and again down the length of the axon.
-One action potential is formed at the axon hillock, and then that same signal travels down the length of the axon.
-When the axon hillock reaches threshold, all of the action potentials are simaltaneously formed down the length of the axon.
-One action potential is formed at the axon hillock, then it triggers the movement of chemical messengers that travel the length of the axon.

Answer 1

The propagation of action potentials occurs when voltage-gated channels open, allowing the depolarization to spread down the axon. In myelinated axons, propagation is faster and saltatory, jumping from one node to the next. The diameter of the axon also plays a role in the speed of propagation.

Step-by-step explanation:

The propagation of action potentials occurs when the depolarization of the cell membrane spreads down the length of an axon, resulting in the opening of voltage-gated ion channels. In unmyelinated axons, this propagation happens continuously as voltage-gated channels are present throughout the membrane. In myelinated axons, propagation is saltatory, meaning it jumps from one node of Ranvier to the next. This saltatory conduction is faster than continuous conduction, and it is aided by the wider diameter of the axon, which reduces resistance.