biology action potentials

resting membrane potential

potassium negative 70 inside cell sodium positive outside cell

threshold level (varies) / polarized

starts with a stimulus opening sodium gates a little enter the cell if an action potential is reached this leads to depolarization.

threshold reached/ depolarization

sodium gates open sodium enters cell making it positive +40 potassium gates remain closed

repolarization

sodium gate closes potassium gates open potassium leaves the cell and the cell becomes more negative

hyperpolarization

too much potassium leaves cell making inside too negative but it is restored by the sodium potassium pump

sodium potassium pump

at the end of an action potential the potassium is on the outside of the cell and the sodium is on the inside this is incorrect so the pump swaps the sodium and potassium back to normal

refractory period

a recovery phase after an action potential when the neuron cannot fire another action potential or requires a stronger stimulus.

axon with myelin (quicker)

one node gets depolarized the next doesn’t