Neuronal Signaling: Action Potentials Flashcards
Define receptor potential
Define postsynaptic potential.
The action potential is an _____________ electrical signal that depends on the opening of __________________.
- All-or-nothing
- Voltage-gated ion Channels
How many subunits does a voltage-gated ion channel have? What is the subunit made of?
What is the green area, the yellow, the blue, and the pink.
Explain how one subunit has a selectivity filter. And how it is gated.
Explain how voltage gating works. (Hint: it’s all about the S4 segment!)
Explain how opening a voltage gated sodium channel creates a positive feedback loop.
If Na+ ions being let into the cell force positive feedback loops, why don’t they keep flowing into the cell until the membrane potential reached equilibrium for Na+? (Side quiz: what is the eq?)
Side quiz: +60mV
The action potential only peaks around +30, because the voltage-gated Na+ channels close due to rapid inactivation.
How does rapid inactivation work?
There are amino acids that are the gate of the channel that immediately conform to a “door” that shuts the channel up when the channel is activated to let Na+ in.
What requirement must be met to initiate an action potential? Both term and function.
Voltage must reach the Threshold Potential.
Once the threshold voltage is met, what chemically happens?
Test:
What causes repolarization?
Opening of voltage-gated K+ channels.
What is this showing you?
K+ open much slower and are activated much longer.
Test:
Define what the refractory period is.
Define the difference between absolute versus relative refractory periods.
What is the trigger zone? Try to be as specific as possible.
Where action potentials are initiated.
What are axon initial segments (AIS)?
In a neuron where are the voltage-gated ion channels localized?
Trigger zone and along the axon.
Test: know all the steps.
Have this memorized!!
