00:01
Hello everyone in this question we will be talking about action potential.
00:06
When a cell is not producing electrical signal and there is positive charge outside and negative charge inside the cell is set to be in the resting potential and in which the leaky channel the leaky potassium channel is open.
00:33
Thus the nerve cell that exhibits the membrane potential is said to be polarized and it has minus 70 millivolt.
00:49
In this the voltage gated channel, the voltage gated potassium and the sodium channel both are closed and only the potassium.
01:00
Leaky channel is open.
01:04
Then we have, then if the net inward flow of positively charged ions increases comparative to the resting phase, the membrane is set to be depolarized, which is known as the action potential.
01:25
This is the rising phase in which the voltage gate sodium channel is open and the potassium weaky channels are open but the voltage gated potassium channel is still closed and it has the and the charge here is 50 millivolt then we have the and then if net outward flow of the positively charged ions increases compared to the resting state membrane the cell is supposed to be in a hyper -polarized state, that is the inside of the cell becomes more negative.
02:11
In this, the voltage -gated sodium channel is closed and the voltage -gated potassium channel is open.
02:23
Also, the potassium -leaky channels are open.
02:29
And here it has minus 90 millie volt of the charges.
02:37
Let's suppose this is the graph here we have the membrane potential and if the y -axis we have the time in milliseconds okay and the graph here is like this.
02:57
Okay, so this is minus 70 and here we have minus 50.
03:03
This here is known as the threshold potential and this phase is called the absolute refractory phase.
03:20
This absolute refractory phase is that even a small stimulus cannot initiate a second action potential.
03:32
Inactivated sodium channel must return to its close state and then only any stimulus can generate the action potential.
03:44
And then from this to this, this is called the relative refractory phase which means the time during which the second action potential can be initiated...