Action Potential Flashcards
What is an action potential?
An electrical current that travels along an axon/dendrite due to ions moving through channel proteins in the neuron’s cell membrane.
What are the characteristics of a polarised (resting) neuron?
A charge difference is maintained between the inside an outside of the cell (Na+ in greater concentration outside, K+ in higher concentration inside). Negative overall charge.
What is the process of a firing neuron? (action potential graph)
1) A stimulus disturbs the membrane of a dendrite, causing sodium channels to open. Sodium ions flow into the neuron and lessen the charge difference.
2) Membrane becomes depolarised as the charges across the membrane are reversed
3) Neighbouring sodium channels open and move the depolarisation along the membrane.
What is the process of a repolarising neuron?
1) Potassium channels open
2) K+ floods out of the cell, repolarising the membrane
3) Sodium-Potassium pumps fully restore the resting membrane potential
What is saltatory conduction?
The “jumping” of an impulse from one node of ranvier to another.
How do anaesthetics work?
By blocking the sodium channels and stopping neurons from reaching the threshold.
