Quiz on Action Potentials and Synapses

What is the resting membrane potential of most neurons?

• +70 mV

• -70 mV

• 0 mV

• -90 mV

The action potential begins when the membrane potential reaches:

• -55 mV

• -70 mV

• 0 mV

• +30 mV

Which ion is primarily responsible for the depolarization phase of an action potential?

• Potassium (K⁺)

• Sodium (Na⁺)

• Calcium (Ca²⁺)

• Chloride (Cl⁻)

What triggers the opening of voltage-gated sodium channels?

• Hyperpolarization

• Threshold stimulus

• Action of neurotransmitters

• Membrane repolarization

During the repolarization phase, which ion exits the neuron?

• Sodium (Na⁺)

• Potassium (K⁺)

• Calcium (Ca²⁺)

• Chloride (Cl⁻)

What is the state of the sodium and potassium channels during the absolute refractory period?

• Both are open

• Sodium channels are inactivated, potassium channels are open

• Sodium channels are closed, potassium channels are closed

• Both are inactivated

Hyperpolarization is caused by:

• Excess sodium influx

• Excess potassium efflux

• Calcium entry

• Chloride exit

The sodium-potassium pump maintains resting membrane potential by exchanging:

• 3 Na⁺ out and 2 K⁺ in

• 2 Na⁺ out and 3 K⁺ in

• 3 Na⁺ in and 2 K⁺ out

• Equal numbers of Na⁺ and K⁺ ions

The threshold potential is typically:

• -70 mV

• -55 mV

• -90 mV

• 0 mV

The peak of the action potential is around:

• +30 mV

• -55 mV

• 0 mV

• -70 mV