Impulse And Myelination Flashcards
Where do action potentials move along?
The length of an axon
When does depolarization occur?
when ion channels open and cause a change in membrane potential
What does voltage-gated mean in terms of nerve impulses?
Open in response to changes in membrane potential.
Why is depolarization seen as a unidirectional wave?
depolarization at one point of the axon triggers the opening of ion channels in the next segment of the axon
When will an action potential of the same magnitude always occur?
A minimum electrical stimulus needs to be generated.
What is another name for the minimum electrical stimulus?
The threshold potential
What is the threshold potential?
-55mV
What is the function of the threshold potential?
The level required to open voltage-gated Na+ channels
What happens if the threshold potential is not reached?
Action potential can not be generated and the neuron will not fire
When are threshold potentials triggered?
The combined stimulation from the dendrites exceed a minimum level of depolarization.
What is myelin?
A fatty white substance which functions as an insulating layer
What is the main purpose of the myelin sheath?
To increase the speed of electrical transmissions via saltatory conductions
What is saltatory conduction?
the way an electrical impulse skips from one node of ranvier to the next down the full length of an axon
What is the effect of saltatory conduction?
an increase in the speed of electrical conduction by a factor of up to 100-fold
