Chapter 11B

Front

What is the absolute refractory period?

Back

The absolute refractory period is the time during which a second action potential cannot be initiated, regardless of the strength of the stimulus, ensuring that each action potential is an all-or-none event.

Front

What is the concentration of sodium (Na+) and potassium (K+) ions inside and outside of a typical neuron?

Back

There is a higher concentration of sodium (Na+) ions outside the cell and a higher concentration of potassium (K+) ions inside the cell.

Front

What is a characteristic of an action potential?

Back

An action potential is characterized by being an all-or-nothing response.

Front

What does repolarization refer to in the context of an action potential?

Back

Repolarization is the process during which the membrane potential returns to a more negative value after depolarization, typically following the peak of the action potential.

Front

What does depolarization refer to in the context of an action potential?

Back

Depolarization is the process during which the membrane potential becomes less negative (more positive) due to the influx of sodium ions (Na+) during an action potential.

Front

What role do voltage-gated sodium channels play in action potentials?

Back

Voltage-gated sodium channels open in response to depolarization, allowing Na+ ions to flow into the cell, which further depolarizes the membrane and initiates the action potential.

Front

What is the significance of the all-or-none principle in action potentials?

Back

The all-or-none principle states that once the threshold potential is reached, an action potential will occur fully; if the threshold is not reached, no action potential will occur.

Front

What happens during the repolarization phase of an action potential?

Back

During repolarization, potassium channels open, allowing K+ ions to exit the cell, which helps restore the negative membrane potential.

Front

What is the threshold potential in the context of action potentials?

Back

The threshold potential is the critical level to which a membrane potential must be depolarized to initiate an action potential.

Front

How does the sodium-potassium pump contribute to maintaining resting membrane potential?

Back

The sodium-potassium pump actively transports 3 Na+ ions out of the cell and 2 K+ ions into the cell, helping to maintain the resting membrane potential and the concentration gradients of these ions.