Factors affecting action potentials and propagation Flashcards
What is the refractory period in the context of action potentials?
The refractory period is the short time after an action potential when the voltage-gated Na channels are inactivated and cannot open to allow Na influx.
What does the refractory period prevent?
- An action potential being generated in the opposite direction
- A second action potential being generated too close to the first
True or False: The refractory period allows for continuous generation of action potentials.
False
Fill in the blank: The refractory period limits the frequency of _______ along a neurone.
action potentials
What factors affect the speed of the nerve impulse?
The diameter of the axon Temperature
Myelination
How does the diameter of the axon affect nerve impulse speed?
The greater the diameter of the axon, the lower the resistance to ion flow, resulting in greater speed of transmission.
How does temperature affect nerve impulse speed?
As temperature increases
RoResp. increases
Rate of ATP synthesis increases
Rate of transfer of ions via Na/K pump increases
Also Ro diffusion increases
What role does respiration play in nerve impulse transmission?
Anything that speeds up respiration rate also speeds up the transmission of nerve impulses.
Local circuit?
Na+ flow into adjacent sections on the axon, depolarising those regions
How does myelination affect rate of impulse transmission
Myelination increases Ro transmission
Myelin insulates the axon
So action potentials only occur at nodes of Ranvier, they jump
What is the jumping action of action potentials between nodes of Ranvier called
Saltatory conduction
How are action potentials transmitted in unmyelinated cells
Propagation via local circuits
