Ion Gradients, Action Potentials, and Axonal Conduction

All flashcards

What is continuous conduction?

Sequential activation of adjacent membrane regions along an unmyelinated axon.

What is saltatory conduction?

Propagation in a myelinated axon by regenerating action potentials at successive nodes of Ranvier.

What does all-or-none signaling mean for an action potential?

Once threshold is reached, the action potential follows its characteristic course; a stronger stimulus does not enlarge it.

What happens during the absolute refractory period?

Another action potential cannot be initiated because many voltage-gated Na⁺ channels are inactivated.

How do astrocytes help support neuronal signaling?

They buffer excess extracellular K⁺ and help maintain the chemical environment around neurons.

Quiz questions

1. A neuron at rest has an approximate membrane potential of −70 mV. What does this value mean?Answer: The inside is about 70 mV more negative than the outside.
2. At approximately what membrane potential does a typical neuron reach threshold for initiating an action potential?Answer: About −55 mV.
3. What happens to a voltage-gated Na⁺ channel near the peak of an action potential?Answer: Its inactivation gate closes, stopping further Na⁺ entry.
4. During which refractory period can another action potential not be initiated?Answer: The absolute refractory period.
5. How does an action potential propagate along a myelinated axon?Answer: It is regenerated at successive nodes of Ranvier.