A nerve impulse travels fastest along axons of diameter.

Question:

A nerve impulse travels fastest along axons of diameter. (a) Myelinated; small

(b) Unmyelinated; small

(c) Myelinated; large

(d) Unmyelinated; large

(e) None of the choices; axon diameter does not affect impulse conduction

Expert Answer

The correctoption is;

(c) Myelinated; large

Explanation:

The speed of a nerve pulse or the speed of an action potential for example is dependent on the presence of a myelin sheath. In the absence of a myelin sheath, an impulse path way is that of the dendrite or axon. As such the the speed of the impulse is reduced. If however, a myelin sheath is present, then the charges of the impulse are transported through the nodes of Ranvier, hence at much higher speed than an impulse on  a non myelinated neuron. The speed of the impulse is increased as the diameter of the dendrite or axon is increased.