Action Potentials - Key Vocabulary

Flashcards covering key vocabulary related to action potentials, membrane potential changes, and signal propagation in neurons.

Action Potential

A change in membrane potential within neurons

Graded/local/postsynaptic potentials

Change in membrane potential between neurons

Depolarisation

Membrane becomes more positive (usually due to Na+ influx).

Repolarisation

Return to resting membrane potential from being depolarised.

Hyperpolarisation

Membrane becomes more negative (usually due to K+ efflux).

Graded Potentials

Variable in size, cause the initial change in membrane potential.

Axon Hillock

The location where action potentials are initiated, also known as the axon initial segment.

Ion Flow

Voltage-gated sodium and potassium channels mediate the ion flow during action potentials.

Absolute Refractory Period

No further action potentials can be generated; Na+ channels are open and then inactivated.

Relative Refractory Period

An action potential can be generated if a large stimulus is applied; some Na+ channels are closed again.

Axon Diameter

Thicker axons propagate action potentials faster due to less resistance to current flow.

Myelination

Insulates the membrane and speeds up propagation, allowing saltatory conduction.

Saltatory Conduction

Action potentials jump from one node of Ranvier to the next in myelinated fibers.

Nodes of Ranvier

Gaps in the myelin where voltage-gated ion channels are localized.

Firing Frequency

Signal information through their frequency: High frequency trains signal a strong stimulus, low frequency trains signal a weaker stimulus.

Neuron structure

• Dendrites: Receive inputs.

• Cell body: Integrates inputs.

• Axon: Sends output signals and generates action potentials.