Physiology Quiz: Refractory Periods of Neurons

Physiology Quiz -
Refractory Periods of Neurons

Neuronal refractory periods occur after the onset of a neuronal action potential and represent a state of decreased neuronal excitability. Two types of refractory periods exist: absolute refractory period and relative refractory period. Test your basic knowledge of neuronal refractory periods by taking this simple quiz.

(1) During this phase of the action potential, if a second stimulus is applied to the neuron (no matter how strong the stimulus), a second action potential will not be generated.

(2) During this phase of the action potential, only a stronger than normal stimulus will lead to the generation of a new potential.

(3) Which of the following is NOT true about the refractory period?

	(A) It is thought that the refractory period is caused by the hyperpolarization phase of the action potential.
	(B) The refractory period is important in preventing the overlap of succeeding action potential.
	(C) The absolute refractory period refers to that time during which a stronger stimulus will lead to the generation of a new action potential.
	(D) The relative refractory period refers to that time during which a stronger stimulus will lead to the generation of a new action potential.
	(E) The relative refractory period coincides with the hyperpolarization phase of the action potential.

(4) Which of the following is NOT true about the absolute refractory period?

	(A) Na⁺ channel inactivation is responsible for the absolute refractory period.
	(B) The absolute refractory period is the time during which another stimulus given to the cell (no matter how strong) will not lead to a second action potential.
	(C) In typical neurons, the absolute refractory period takes about 5 ms.
	(D) The molecular basis of the absolute refractory period is described by the ball-and-chain model.
	(E) All of the above are true about the absolute refractory period.

(5) In a typical vertebrate axon, the absolute refractory period is 1.0 ms and the relative refractory period is 4.0 ms. Thus, the axon is refractory for a total of 5.0 ms. If the axon is continuously stimulated with stimuli only large enough in amplitude to ensure excitation when the neuron is at rest, what is the highest frequency of action potentials that can be generated?

	(A) 50 Hz
	(B) 100 Hz
	(C) 200 Hz
	(D) 500 Hz
	(E) 1000 Hz

(6) In a typical vertebrate axon, the absolute refractory period is 1.0 ms and the relative refractory period is 4.0 ms. If the axon is continuously stimulated with stimuli that can be adjusted in strength to be as strong as necessary to ensure excitation, what is the highest frequency of action potentials that can be generated

	(A) 50 Hz
	(B) 100 Hz
	(C) 200 Hz
	(D) 500 Hz
	(E) 1000 Hz

(7) Which of the following is/are true of the absolute refractory period?

	(A) Na⁺ channel inactivation is responsible for the absolute refractory period.
	(B) The absolute refractory period is the time during which another stimulus given to the cell (no matter how strong) will not lead to a second action potential.
	(C) The absolute refractory period takes about 5 ms.
	(D) The absolute refractory period precedes the relative refractory period.
	(E) The absolute refractory period sets the upper limit for the maximum frequency of action potentials generated.

(8) Approximately, how long is the absolute refractory period of neurons?

	(A) 1-3 ms
	(B) 3-5 ms
	(C) 5-10 ms
	(D) 10-100 ms
	(E) 100-250 ms

(9) Approximately, how long is the relative refractory period of neurons?

	(A) 1-3 ms
	(B) 3-5 ms
	(C) 5-10 ms
	(D) 10-100 ms
	(E) 100-250 ms