00:01
Okay, let's diagram here the action potential.
00:04
So here you have the y -axis and here you have the x -axis.
00:08
In the y -axis you're going to have the voltage and in the x -axis you're going to have the time.
00:16
This is your resting magnet potential, let's suppose minus 70 millivolts.
00:20
And here you have the threshold potential that is minus 60 millivolts.
00:26
This is the voltage that your cell needs to reach in order to start action potential, okay? and this is the resting magnet potential.
00:35
If there is a stimulus that is not strong enough to cause an action potential, then the voltage is going to rise, but it is not going to reach the threshold potential, so it is going to decrease.
00:46
But if there is a stimulus that is strong enough to reach the threshold potential, then the voltage is going to rise like this.
00:54
And why? well, this phase here is the polarization phase of action potential and it occurs because of the opening of voltage -gated sodium channels, okay? so your voltage or these channels are going to open and a lot of sodium ions are going to enter inside of the cell and as sodium ions are positively charged, then the cell is going to get electropositive.
01:23
So your voltage is going to get up to plus 30 millivolts approximately, okay? at this point, these channels are going to close and what are going to open are going to be voltage -gated potassium channels and these potassium channels are going to move potassium out of the cell...