Action Potential Flashcards
Events that initiates the action potential.
Electrical
Chemical
Mechanical
Stimulation that causes increase in membrane potential. what does it cause
opening of voltage gated sodium channels.
what does the rhythmical discharge cause
Rhythmical beat of the heart (SA node)
Rhythmical peristalsis of the intestines (slow wave)
Neuronal events such as the rhythmical control of breathing e.g., Dorsal respiratory group of neurons.
Local anaesthetics bind selectively to what?
voltage-gated sodium channels (VGSCs).
What does the binding of local anesthetic mechanism to VGSCs do?
Prevents the Na+ channel to open, inhibiting Na+ influx=block the propagation of action potentials.
Mention rest membrane potential in different cell types
Neurons -60 to -70
Skeletal muscle -85 to -95
Smooth muscle -50 to -60
Cardiac -80 to -90
Events caused by Rhythmical discharges
Rhythmical beat of the heart
Rhythmical peristalsis
Rhythmical control of breathing
Name the gates of Na+ channel
Activation gate (outside the channel)
Inactivation gate( inside the channel)
3 stages of sodium channel
- Closed but available
- Open
- Inactivated
When will the inactivation gate re-open after it has closed on the 3rd phase?
Until the membrane potential returns to or near the original RMP
When do the potassium channels open?
Almost the same time as the closure of sodium inactivation gate
A process where AP jumps from one node to another
Saltatory conduction
A second action potential CANNOT be produced, regardless of the stimulus strength
Absolute refractory period
Action potential can be generated but threshold is more difficult to reach because depolarisation has to overcome additional membrane hyperpolarisation.
Relative refractory period
