The Action Potential Flashcards
What does the negative charge of around -65mV inside the membrane become?
A positive charge of around +40mV
What does the energy of a stimulus received by a receptor or nerve ending cause?
A temporary reversal of the charges on the axon membrane
What is this change in the charges known as?
The action potential
When the charge changes from -65mV to +40mV, what is the membrane said to be?
Depolarised
What causes depolarisation?
The channels in the axon membrane change shape and hence open or close, depending on the voltage across the membrane
What are the channels in the axon membrane called?
Voltage gated channels
What does the energy of the stimulus cause?
Some sodium voltage-gated channels in the axon membrane to open
What does the movement of sodium ions into the axon trigger?
A reversal in the potential difference across the membrane and more sodium channels to open
What happens once the action potential of around +40mV has been established?
The voltage gates on the sodium ion channels close and the potassium ion channels begin to open
What happens when the potassium voltage gated channels open?
The electrical gradient reverses causing more potassium ion channels to open
What does the movement of potassium ions cause?
Repolarisation of the axon
What happens after the mass diffusion of potassium ions?
The potassium voltage gated channels close and the resting potential is re-established
