- Created by: 11APhillips
- Created on: 30-12-19 15:25
1. The threshold potential is reached, causing time and voltage sensitive sodium channels to open, causing Na+ influx.
2. Time and voltage dependant calcuium channels opne more slowly, causing efflux of K+, repolarising the membrane.
3. The conducatnce is proportional to the number of ion channels open.
4. Increased K+ conductance causes an undershoot of the resting otential, leading to hyperpolarisation and the formation of a relative refractory period, where action potential propagation is inhibited (the absolute refractory period is during the depolarisation, where it is impossible for a new action potential to be formed).
- Cl channels are not voltage dependant.
- The resting potential is maintained by sodium:potassium pumps.
- Using conductance instead of permeability in the constant field equation is preferred as you don't have to use radiation to measure the conductance.
- A the start and end of the action potential, K+ conductance is highest and at the peak of the action potential Na+ conductance is highest.
- Conductance (g) is the inverse of resistance
- The membrane can store charge and so is a capacitor.
- The charge in a membrane is proportional to the potential across it, with the proportionality constant being the capacitance: Q = E CM
- CM = A*gamma/d
- gamma = dielectric constant d = membrane thickness A = membrane area
- This is the speed at which the action potential travels.
- It is related to the space and time constant.
- The time constant is increased (spread slowed down) by depositing some…