Amoeba Sisters - Action Potential

What characteristic defines an excitable cell?

• A cell that can generate an electrical signal from a stimulus.

• A cell that can only receive electrical signals.

• A cell that is always positively charged.

• A cell that only responds to chemical stimuli.

What is the primary function of the sodium-potassium pump in maintaining a cell's resting membrane potential?

• It moves two sodium ions into the cell and three potassium ions out of the cell.

• It moves three sodium ions out of the cell and two potassium ions into the cell.

• It passively allows sodium and potassium ions to flow across the membrane.

• It only transports negatively charged ions.

What does a neuron's resting membrane potential of -70 millivolts (mV) indicate?

• The inside of the neuron is 70 mV more positive than its surroundings.

• The outside of the neuron is 70 mV more negative than its surroundings.

• The inside of the neuron is 70 mV more negative than its surroundings.

• There is no electrical potential difference across the membrane.

What event must occur for an action potential to be triggered in a neuron?

• The cell must become more negative than its resting potential.

• The membrane potential must reach a specific threshold level.

• Potassium ions must rush into the cell.

• All leak channels must close completely.

What is the outcome if a stimulus causes a subthreshold depolarization in a neuron?

• A partial action potential will be generated.

• A full action potential will be generated, but with reduced amplitude.

• No action potential will be generated.

• The neuron will immediately hyperpolarize.

During the rising phase of an action potential, what is the primary event that causes the membrane potential to become more positive?

• Potassium ions flowing out of the cell.

• Sodium ions flowing into the cell.

• Chloride ions flowing into the cell.

• Calcium ions flowing out of the cell.

Which type of ion channel opens in response to a specific signaling molecule, such as a neurotransmitter, to initiate a change in membrane potential?

• Voltage-gated ion channels.

• Mechanically-gated ion channels.

• Ligand-gated ion channels.

• Leak channels.

What mechanism primarily ensures that an action potential travels in only one direction along an axon?

• The continuous opening of voltage-gated potassium channels.

• The inactivation of voltage-gated sodium channels in the preceding segment.

• The presence of the myelin sheath.

• The active transport of ions by the sodium-potassium pump.