Nerve Action Potentials Study Guide

These flashcards cover key concepts related to nerve action potentials, including resting potential, depolarization, repolarization, refractory periods, propagation methods, and synaptic transmission.

What is the term for the electrical potential difference across a neuron's membrane at rest?

Resting Membrane Potential (RMP)

What ions primarily influence the resting membrane potential?

Sodium (Na+) and Potassium (K+) ions.

What happens during depolarization in a neuron?

Sodium gates open, allowing Na+ ions to enter, making the inside of the cell positively charged.

What is the role of the axon hillock?

It determines if the threshold value is reached to initiate an action potential.

What happens during repolarization?

Potassium (K+) gates open, allowing K+ to exit, returning the membrane potential to negative.

What is hyperpolarization?

When the membrane potential becomes more negative than the resting potential due to excessive K+ outflow.

What is the significance of the absolute refractory period?

A period during which a second action potential cannot be initiated, regardless of the stimulus.

What is the difference between absolute and relative refractory periods?

Absolute: No action potential possible; Relative: Action potential possible with a stronger-than-normal stimulus.

What is saltatory conduction?

The process by which action potentials jump between the nodes of Ranvier in myelinated axons.

What effect does myelination have on action potential propagation?

It increases the speed of conduction, making it 10 times faster than in unmyelinated fibers.

What is a threshold value in the context of action potentials?

The critical level to which a membrane potential must be depolarized to trigger an action potential.

What are voltage-gated sodium channels responsible for during an action potential?

They open in response to depolarization, allowing Na+ ions to flow into the neuron.

What role does calcium (Ca2+) play at the axon terminal?

Ca2+ rushes in to facilitate the release of neurotransmitters via exocytosis.

What are the two types of propagation mentioned in the notes?

Continuous propagation (unmyelinated) and saltatory conduction (myelinated).

What determines if an action potential is generated?

The strength of the stimulus and whether it reaches the threshold.

What type of channels are responsible for the conduction of local potentials in unmyelinated axons?

Leakage channels.

What is the process called when action potentials are generated at the nodes of Ranvier in myelinated axons?

Saltatory conduction.

What happens if a stimulus is strong enough during the refractory period?

It can initiate a new action potential during the relative refractory period.

What happens during the process of exocytosis at the synaptic terminal?

Neurotransmitters are released from synaptic vesicles into the synaptic cleft.

What is the main difference in the conduction speed between myelinated and unmyelinated axons?

Myelinated axons conduct action potentials much faster due to saltatory conduction.