Genderattion And Transmission Of Action Potential Flashcards
What does every cell have
A slightly polarised membrane - meaning there is an uneven distribution of ions across the membrane. This generates a potential difference. When th cell isn’t being used, it is maintained at a resting potential in which it can be stimulated
What does the sodium potassium ion pump do (1)
3 sodium ions pumped out and 2 potassium ions pumped in so this requires ATP to change the shape of the pump to allow the potassium and sodium to be carried across.
What does the voltage gated sodium ion Chanel’s do (2)
This is closed not prevent them coming back in
What does the non voltage gated potassium channel do? (3)
The potassium pumped in can still leave the cell. As the pumped in potassium means that there is a higher conc snide the cell. So it can also leave by facilitated diffusion.
What is permanently inside the cell?
Negative ions that stay inside the cell, resulting in a negative charge inside the cell compared to a positive charge outside the cell. This results in a resting potential at -70mV
What is action potential
The state at which the membrane is stimulated
What is the first part of action potential
Depolarisation - the process of having a balance of negative charge inside and positive outside is reversed.
When membrane does receive signal and gets stimulated, it releases nerve impulse. The first few sodium channels detect this and will receive energy from this stimulus and open. Now hella high sodium Channels open due to them being pumped out, will diffuse back in by facilitated diffusion. Positive ions within cell until it reaches threshold potential of -55mV
What happens once the threshold potential has occurred
It will stimulate more voltage gated sodium channels to open, causing a massive influx of sodium ions. Only the first few could open due to the small energy transferred from the initial stimulus
What happens now that all voltage gated sodium channels are open?
Because of big influx into the cell, we have a positive charge inside, compared to a little negative charge outside. This will keep going until we get +40mV
What is repolarisation
Once +40mV has been reached, the sodium channels will close and voltage gated potassium ion channels open. Prior it was only non voltage gated potassium ions. Now more k+ can diffuse outside the cell after being pumped in. Because of the drop in polarisation due to K+ moving out, ion pumps will reactivate. Distribution of ions across membrane can be reinstated
Before ion pumps reactivate what happens
Hyperpolarisation - when the resting potential is lower than -70mV. But this is quickly reestablished when ion pumps activated
