Muscle Physiology 1: Converting a Nerve Impulse into a Muscle Action Potential

What is the primary role of sodium ions in depolarization?

• To decrease the charge inside the cell

• To move potassium ions out of the cell

• To inhibit muscle contraction

• To propagate the action potential

What is the neuromuscular junction?

• A type of muscle fiber

• The synapse between a motor neuron and a muscle cell

• A type of neurotransmitter

• A calcium storage site

What triggers the exocytosis of acetylcholine at the neuromuscular junction?

• Influx of calcium ions

• Influx of sodium ions

• Efflux of potassium ions

• Efflux of chloride ions

What happens when acetylcholine binds to its receptor?

• Potassium channels open

• Chloride channels open

• Sodium channels open

• Calcium channels close

What type of channel is opened by acetylcholine binding?

• Temperature-gated ion channel

• Mechanically-gated ion channel

• Ligand-gated ion channel

• Voltage-gated ion channel

What is the main function of voltage-gated sodium channels in muscle cells?

• To store calcium ions

• To inhibit depolarization

• To propagate action potentials

• To release neurotransmitters

What is the result of sodium influx through voltage-gated sodium channels?

• Stabilization

• Depolarization

• Hyperpolarization

• Repolarization

What is the role of the voltage sensor in a voltage-gated sodium channel?

• To release calcium ions

• To detect changes in temperature

• To sense changes in voltage

• To bind acetylcholine

What is the direction of sodium ion movement during depolarization?

• From the cytosol to the extracellular fluid

• From the cytosol to the nucleus

• From the extracellular fluid to the cytosol

• From the nucleus to the cytosol

What is the effect of depolarization on the muscle cell membrane?

• It decreases the positive charge inside the cell

• It increases the positive charge inside the cell

• It decreases the negative charge outside the cell

• It increases the negative charge inside the cell