Question

The nature of nerve impulse is
(a) Physical
(b) Chemical
(c) Electrochemical
(d) Biophysical

Answer 1

Nerve impulse is a rapidly moving change in electrical membrane potential called an action potential. It can be generated when a neuron’s membrane potential is changed by chemical signals from a nearby cell. It is a very rapid and brief polarization of the membrane of the nerve fiber.

Complete answer:
Nerve impulses are electrochemical excitation waves, passing along the membranes of stimulated neurons. Transmission of nerve impulses involves three fundamental processes, namely; maintenance of membrane potential, generation of action potential, and propagation of action potential. The plasma membrane of neurons is electrically polarized, because one side of it is electrically negative and the other side is electrically positive, with respect to each other. The potential difference existing across a nerve membrane is known as membrane potential oar bio-electric potential. An unexcited or non- stimulated neuron is called a resting neuron. The transmembrane potential of an excitable resting neuron is called resting potential and that of an active neuron, which is stimulated to undergo electrical changes is called action potential.
So, the correct answer is ‘Electrochemical’.

Additional information:
- Resting potential is a physio- chemical phenomenon, established and maintained by the differential distribution of sodium and potassium ions across the axon membrane.
- Nerves and nerve fibers are excitable and capable of transmitting messages as electrical pulses known as nerve impulses or nerve signals.
- excitability is the ability of nerve cells to respond to stimuli and to convert them as nerve impulses.

Note:
- A nerve Impulse is an environmental change or factor that can evoke a nervous reaction and generate a nerve impulse. It can be mechanical, chemical, thermal or electrical.
- When a resting neuron is excited or stimulated, a cyclic series of electrochemical changes take place in it. This is known as action potential or action current.
- Action potential is a very rapid and extremely short living change in transmembrane action potential that lasts only for a few thousands of seconds.