Neural signalling - action potentials Flashcards
What causes an action potential to be generated in a neurone?
An influx of positively charged sodium ions into the axon.
What is depolarisation in the context of neurones?
The process where the membrane potential becomes less negative due to sodium ions entering the axon.
What are voltage gated ion channels?
Ion channels that open and close in response to changes in the electrical potential across the membrane.
What happens when a neurone is stimulated?
Sodium ion channels in the axon membrane open, allowing sodium ions to enter.
What is the resting potential of a neurone?
-70 mV.
What is the threshold potential for initiating an action potential?
-50 mV.
What occurs after an action potential is generated?
It is propagated along the length of the axon.
What triggers another action potential in a section of the axon?
Depolarisation of the membrane causes voltage gated sodium channels to open.
What happens during repolarisation?
Potassium ions diffuse out of the axon, making the inside more negatively charged.
What is hyperpolarisation?
A period during which the membrane potential is more negative than resting potential.
What is the refractory period?
The time during which the membrane is unresponsive to stimulation after an action potential.
What is the all-or-nothing principle?
Action potentials are either fully generated or not at all, depending on whether the threshold potential is reached.
How does stimulus size affect action potentials?
A stronger stimulus increases the frequency of action potentials transmitted along the neurone.
What are local currents in the context of nerve impulse propagation?
Movements of sodium ions that facilitate depolarisation in adjacent sections of the axon.
Fill in the blank: The inside of the axon becomes less negative during _______.
depolarisation
True or False: Not all channels in a neurone membrane are voltage gated.
True
What restores the resting potential after an action potential?
Sodium-potassium pumps.
