Neuronal Action Potential Flashcards
What do action potentials in neuronal cell membranes result from?
Effects of membrane depolarization on voltage-dependent ion channels
When are sodium channels activated?
Depolarization from resting potential to approx -55mV
What does the influx of sodium ions cause?
Upstroke of action potential i.e. depolarization
How are potassium channels activated?
By depolarization after a delay
How does potassium affect the action potential?
Repolarizes the membrane and sodium channels become inactivated
What happens with full activation of the potassium channels?
Outward flow of current causes undershoot as membrane potential becomes more negative than resting potential
What happens during the refractory period?
Sodium channels recover from inactivation
Where is there a high density of Na channels?
In the exposed axon membrane at the Nde of Ranvier
What are blockers of sodium channels?
Tetrodotoxin
Saxitoxin
Lidocaine
What are blockers of potassium channels?
Tetraethylammonium
4-aminopyridine
Cs+
How are axons grouped into types?
Differences in myelination and diameter
