Q.Explain the properties of nerve fibres.

Properties of nerve fibres: irritability/excitability (ability to respond to a stimulus by generating an impulse), conductivity (ability to transmit the nerve impulse along its length), an all-or-none response (a stim...

Nerve fibres are excitable, conduct impulses in an all-or-none fashion, need a recovery period between firings, and conduct faster if myelinated.

A nerve fibre (axon) shows several defining physiological properties. Irritability (excitability) is its ability to respond to an adequate stimulus by generating an electrical nerve impulse (action potential). Conductivity is its ability to propagate that impulse, without loss of strength, along its entire length to the next neuron or effector. Nerve fibres obey the all-or-none law: if a stimulus reaches or exceeds the threshold intensity, the fibre generates a full-amplitude impulse; if the stimulus is below threshold, no impulse is generated at all — there is no partial or graded impulse within a single fibre. After firing an impulse, a nerve fibre passes through a brief refractory period during which it is temporarily unable (absolute refractory period) or only able with a stronger-than-normal stimulus (relative refractory period) to generate another impulse, limiting the maximum frequency of impulse transmission. While an isolated nerve fibre can conduct an impulse in either direction from the point of stimulation, in an intact reflex pathway, transmission across synapses is unidirectional (from the presynaptic to the postsynaptic neuron only, since only the presyn …