Understanding Action Potentials

What initiates an action potential in a neuron?

• The movement of potassium ions out of the cell

• The release of neurotransmitters binding to receptors

• The closing of voltage-gated sodium channels

• The hyperpolarization phase

What is the resting membrane potential of a neuron?

• -55 millivolts

• -70 millivolts

• +30 millivolts

• 0 millivolts

What role do neurotransmitters play in generating an action potential?

• They close potassium channels

• They open sodium-potassium pumps

• They bind to receptors, allowing sodium ions to enter the neuron

• They hyperpolarize the neuron

Which ions primarily move into the neuron during depolarization?

• Chloride

• Magnesium

• Potassium

• Sodium

At what voltage do voltage-gated sodium channels open?

• 0 millivolts

• -55 millivolts

• -70 millivolts

• +30 millivolts

Tags

NGSS.HS-PS3-5

What is the significance of the -55 millivolts threshold in neurons?

• It indicates the neuron is in the repolarization phase

• It signals the neuron to hyperpolarize

• It triggers the opening of voltage-gated sodium channels

• It is the resting membrane potential

What happens when the neuron's interior reaches +30 millivolts?

• Sodium channels close and potassium channels open

• Potassium channels close

• Sodium channels open further

• Neuron immediately returns to resting potential

What triggers the opening of voltage-gated potassium channels?

• Reaching 0 millivolts

• Reaching -55 millivolts

• Reaching +30 millivolts

• Reaching -70 millivolts

What is hyperpolarization?

• The opening of sodium channels

• A phase where the neuron's interior becomes more negative than the resting potential

• A phase where the neuron's interior becomes more positive than the exterior

• The closing of potassium channels

How does the neuron reset to its resting membrane potential?

• By reversing the movement of potassium

• By opening more sodium channels

• Through the action of sodium-potassium pumps

• By closing all ion channels