A nerve impulse travels from the axon hillock to the synaptic terminals by propa

Question

A nerve impulse travels from the axon hillock to the synaptic terminals by propagating a series of action potentials along the axon. The speed of conduction increases with the diameter of the axon and, in many vertebrate axons, with myelination. Action potentials in axons insulated by myelination appear to jump from one node of Ranvier to the next, a process called saltatory conduction.

If an action potential lasts from the beginning of the rising phase to the point of maximal undershoot, what is the maximum frequency at which a neuron could fire action potentials? (Assume that the neuron can fire only one action potential at a time and that the refractory period following the action potential is negligible.)

0.0023 events per second (Hz) 0.0046 events per second (Hz) 220 events per second (Hz) 430 events per second (Hz)

Explanation / Answer

ANS: C. 220 events per second (Hz).

Explanation:

Refractory period: It is the time period of 1 msec after one action potential is initiated and before the next one is initiated. Normal physiologically action potential frequency is up to 200-300 per second (Hz). Some times higher frequencies can also observed. The maximum frequency is completely depends on absolute Refractory period. But it can last between 1-2 ms, the maximum frequency response is 500-1000 s1 (Hz).

If an action potential last from the beginning of the rising phase to the end of the falling phase it took 2 milliseconds. So the maximum frequency of a neuron action potential is 220 events per second (Hz).

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