Action Potential

Sodium potassium pump

3 sodium out 2 potassium in

creates an electrochemical gradient

Ion channels

Most are voltage gated, which open at specific voltages

Others are ligand-gated, open when a neurotransmitter latches onto its receptor

Movement evens out the ions and electrochemical gradient

Graded potential

Little change in the membrane potential

Action potential

So a small change happens causing a channel to open, for action potential to kick in we need about -55mV from -70mV otherwise nothing happens. Once that is reached then all the voltage gated sodium channels open making the mV positive about 40 mV (DEPOLARIZATION). Then repolarization kicks in. the voltage gated potassium opens and then they go out, they over shoot a bit and pass the resting membrane potential REPOLARIZATION. The over shoot is called HYPERPOLARIZATION.

It cannot respond to any other stimulus this is called the refractory period.

Spatial summation

lots of pre synaptic neurons communicating with one post synaptic (within 10 micrometers)

Temporal summation

one pre synaptic, very fast communication w one post synaptic (10milliseconds)

Spaciotemporal summation

few pre synaptic neurons firing fast to 1 post synaptic (fastest way to get to action potential)