Muscle Physiology 2: Voltage-Gated Potassium Channels and the Action Potential

The video tutorial covers the role of voltage gated sodium and potassium channels in muscle cell action potentials. It explains how sodium influx initiates depolarization, while potassium efflux leads to repolarization. The tutorial also highlights the differences in voltage sensitivity between these channels and introduces the sodium-potassium pump, which restores ion balance after an action potential.

What is the primary function of the voltage sensor in voltage-gated sodium channels?

• To bind to neurotransmitters

• To sense changes in charge across the membrane

• To detect changes in temperature

• To transport ions across the membrane

What initiates the propagation of an action potential along the sarcolemma?

• Influx of calcium ions

• Efflux of potassium ions

• Influx of sodium ions

• Efflux of chloride ions

What happens to the voltage-gated sodium channels during the refractory period?

• They inactivate and cannot open

• They remain open

• They transport potassium ions

• They become more sensitive

What is the effect of sodium influx on the membrane potential?

• It stabilizes the membrane potential

• It makes the membrane potential more negative

• It makes the membrane potential more positive

• It has no effect on the membrane potential

How do voltage-gated potassium channels differ from sodium channels in terms of activation?

• They require a higher positive charge to open

• They open simultaneously with sodium channels

• They require a lower positive charge to open

• They are not voltage-sensitive

What is the primary difference in activation between voltage-gated sodium and potassium channels?

• Sodium channels require a higher positive charge

• Sodium channels are not voltage-sensitive

• Potassium channels are not voltage-sensitive

• Potassium channels require a higher positive charge

During which phase of the action potential does potassium efflux occur?

• Hyperpolarization

• Resting potential

• Repolarization

• Depolarization

Which ion movement is responsible for the repolarization phase?

• Potassium efflux

• Sodium influx

• Calcium influx

• Chloride influx

What is the role of the sodium-potassium pump after an action potential?

• To increase the concentration of sodium inside the cell

• To generate action potentials

• To restore ions to their resting positions

• To decrease the concentration of potassium outside the cell

What is the role of the sodium-potassium pump in maintaining the resting membrane potential?

• It pumps sodium out and potassium into the cell

• It allows potassium to leave the cell

• It allows sodium to enter the cell

• It generates action potentials