action potentials are generated to move information along axons
action potentials spread across the axon when one part of the axon is depolarised
depolarisation in one section opens voltage-gated sodium and potassium channels in adjacent sections of the axon. This is because sodium ions diffuse sideways along the neurone. This is called a local current. The action potential continues to move in the same direction and will not reverse
the concentration of sodium ions in the cytoplasm behind the action potential is high.
speed of transmission of an action potential
myelinated neurone speeds up transmission.
nodes of ranvier cause saltatory conduction
other factors affecting speed of transmission
length of axon
diameter of the axon - bigger diameter, faster transmission
action potential is always the same
how can action potentials differ
the frequency changes. Stronger stimuli produce more action potentials in a given time (higher frequency) compared to weaker stimuli
The "all or nothing law" states that either an action potential is generated or not. The potential difference needs to reach the threshold (-50mv) to generate an action potential
