Action Potentials Flashcards
What is the threshold?
Where enough voltage gated Na channels open, causing the ‘pop’
What is the rising phase?
When inside the cell is negative, there is a large force driving Na ions in which causes depolarization.
What is overshoot?
Em is greater than OmV
What is the falling phase?
Voltage gated Na channels inactive, so K rushes out causing repolarisation
What is undershoot?
Em goes towards Ek until K channels close which causes hyperpolarisation
What is the absolute refractory period?
The time measured from the onset of the action potential, during which another cannot be triggered
What is the relative refractory period?
The time following an action potential during which more depolarising current is required to meet threshold.
What does tetrodotoxin do?
Blocks the pore of Na+ channels in the membranes excitable cells.
What does ethanol do?
Produces anaesthesia that is not fully reversible.
What is lignocaine used for?
Stopping certain types of cardiac arrhythmia
What is tocainide used for?
Neuropathic pain
What did phenytoin used for?
Epileptic disorders
