A and P chp 12 pt 2 - speed of action potential, all or none principle

What are two ways impulse conduction can be faster?

• myelinated axon

• axon with large diameter

what is impulse conduction faster in a myelinated axon?

saltatory propagation - action potential jumps from node to node

why is an axon with a larger diameter faster?

it offers lower resistance = ions can move more freely within the cytoplasm, this is necessary to depolarize adjacent regions of the plasma membrane.

what is the ALL-OR-NONE principle?

If a stimulus is strong enough to initiate an action potential, then the action potential will be conducted at a constant magnitude and rate along the length of the axon.

• action potentials will occur at maximal depolarization or not at all.

How then does the neuron transmit information about the strength and duration of the stimulus that started the action potential?

• frequency of the action potential propagation

• 1 AP/Sec → produces MUSCLE TWITCH

• 100 Ap/sec → produces MUSCLE TETANY