lecture 3 Flashcards
how is action produced? how fast is it?
- APs are produced by voltage gated sodium channels.
- Fast deplorization (~ 1 ms).
- Speed of Ap is around 200 mph
How can you terminate an AP?
-Potassium channel activate and Sodium channels inactivate.
What is the outcome of graded potential?
it produces the deplorization required for action potential.
What happens during the recovery of sodium and potassium channels?
the absolute and relative refractory periods.
Where is the graded potential turned into action potential?
-Graded potential turn into AP if it reaches the trigger zone without diminishing. If a stimulus initiates a strong enough graded potential that would reach the trigger zone and deplorize enough Na channels to meet the threshold then AP is the outcome.
What distinguishes graded potential at synapse?
-It has a variable amplitude that could be positive or negative (EPSPS or IPSP) and it’s slow.
What distinguishes AP at Synapse?
- Its an all or none reaction
- fixed size action not variable like graded potential.
- EPSPs only
- threshold to activate.
What 3 types of channel work to keep the Action potential mechanism>
1) Unregulated leak channels help maintain a resting potential.
2) Synaptic ligand gated channels which produces the graded potential
3) Voltage gated channels that allow depolrization and produce the action potential.
When would the Na current become regenerative?
When it exceeds the potassium current.
Why do we end up getting hyperpolarization undershoot?
Because Potassium channels do not close as fast as they should and we end up getting this undershoot because they dont deactivate on time.
