Action Potential of the Nerve Cell

A typical neuron has a resting membrane potential of about:

• +70 mV

• +70 V

• −70 mV

• −70 V

• All of the above are observed at rest

The following ion(s) is/are involved in the neuronal action potential:

• Sodium (Na⁺) Potassium (K⁺)

• Calcium (Ca²⁺)

• Chloride (Cl⁻)

• All of the above

At the peak of the action potential, the membrane potential is:

• exactly at the Na⁺ equilibrium potential (V_Na)

• close to but more positive than the Na⁺ equilibrium potential (V_Na)

• close to but less positive than the Na⁺ equilibrium potential (V_Na)

• exactly at 0 mV

• the same as the resting membrane potential (V_rest)

At what membrane voltage do neuronal voltage-gated Na⁺ channels become activated?

• −70

• −50

• 0 mV

• +50 mV

• None of the above

At what membrane voltage do neuronal voltage-gated K⁺ channels become activated?

• −70

• −50

• 0 mV

• +50 mV

• None of the above

The spike phase of the neuronal action potential is due to:

• the opening of voltage-gated Na⁺ channels

• the opening of voltage-gated K⁺ channels

• the closure of resting K⁺ channels

• the opening of voltage-gated Cl⁻ channels

• None of the above

The hyperpolarization phase of the action potential is due to:

• the opening of voltage-gated Cl⁻ channels

• the prolonged opening of voltage-gated K⁺ channels

• the closure of resting Na⁺ channels

• due to the closure of Cl⁻ channels

• None of the above

Upon opening, voltage-gated K⁺ channels of neurons enter an inactivate state in a manner similar to voltage-gated Na⁺ channels of neurons.

• True

• False

In the nervous system, the strength of the stimulus is coded into:

• The frequency of action potentials generated

• The amplitude of action potentials generated

• Both the frequency and amplitude of action potentials generated