Want this question answered?
It starts at the axonal hillock and it propagates down the axon into the terminal boutons.
To speed up transmission of the action potential from where it originates (axon hillock) to where it ends (axon terminal), the action potential propagates by 'saltatory conduction' - and the structure that makes this possible is the insulating layer of myelin sheath that wraps around the axon, arranged in 'nodes' along its length. Technically, it's the gaps between the nodes (nodes of Ranvier) that cause the action to continually propagate and maintain its fast conduction velocity.
The velocity of propagation of an action potential depends on axoplasm resistance and membrane resistance. Axoplasm resistance explains how fast a charge can move within an axon. The larger the diameter of the axon, the more quickly it can pass through. Membrane resistance describes how permeable the membrane is to the ion. The less permeable, the faster the propagation of the action potential. Therefore, myelination increases the membrane resistance and ultimately allows for fast propagation. In demyelinating diseases, there is little or sometimes no myelin covering the axons. In these cases action potentials will slow down or completely cease.
An action potential is not passively propagated down the axon. There have to be ion channels along the axon or else the action potential will gradually decay. So the the rate of that the action potential 'travels' is dependent on the passive property called the length constant of the axon (factor in capacitance, axon diameter) plus the density of ion channels.
axon
It starts at the axonal hillock and it propagates down the axon into the terminal boutons.
To speed up transmission of the action potential from where it originates (axon hillock) to where it ends (axon terminal), the action potential propagates by 'saltatory conduction' - and the structure that makes this possible is the insulating layer of myelin sheath that wraps around the axon, arranged in 'nodes' along its length. Technically, it's the gaps between the nodes (nodes of Ranvier) that cause the action to continually propagate and maintain its fast conduction velocity.
The velocity of propagation of an action potential depends on axoplasm resistance and membrane resistance. Axoplasm resistance explains how fast a charge can move within an axon. The larger the diameter of the axon, the more quickly it can pass through. Membrane resistance describes how permeable the membrane is to the ion. The less permeable, the faster the propagation of the action potential. Therefore, myelination increases the membrane resistance and ultimately allows for fast propagation. In demyelinating diseases, there is little or sometimes no myelin covering the axons. In these cases action potentials will slow down or completely cease.
Under normal circumstances action potential will proceed unilaterally. An action potential cannot proceed down an axon and depolarize in the reverse direction on the same axon. It must carry information on one axon in one direction and then on another axon in a separate direction. In a lab you can depolarize neurons in the middle of an axon and it will depolarize bilaterally.
An action potential is not passively propagated down the axon. There have to be ion channels along the axon or else the action potential will gradually decay. So the the rate of that the action potential 'travels' is dependent on the passive property called the length constant of the axon (factor in capacitance, axon diameter) plus the density of ion channels.
axon
axon hillock
The spike initiation zone, also called axon hillock, is the point where the cell body of the neuron meets the axon and is the point where most action potentials are initiated.
Action potentials are generated on a part of the neuron called the 'axon hillock' - the proximal most portion of the axon.
Axon, telondendria
The Na+ diffusing into the axon during the first phase of the action potential creates a depolarizing current that brings the next segment, or node, of the axon to threshold.
The Na+ diffusing into the axon during the first phase of the action potential creates a depolarizing current that brings the next segment, or node, of the axon to threshold.