Chapter 12, Problem 13RQ

Summary Introduction

To determine:

The composition of nerves.

Introduction:

A cable-like organ that has many axons arranged in parallel bundles is called a nerve. They are enclosed by the successive wrapping of connective tissue. They contain myelinated as well as non-myelinated sensory and motor neurons. The nerve cells generate and transfer an electrical impulse from one cell to the other.

 

Correct answer:

 Axons of afferent and efferent neurons.

Explanation for the correct answer:

Option (d) is given as axons of afferent and efferent neurons. The signals are received up by the sensory receptors that are located throughout the body surface and carried by the nerve fiber of the peripheral nervous system into the central nervous system by the afferent neuron. While signals are carried away from the central nervous system by the nerve fibers of the peripheral nervous system to innervate the muscles or glands causing these organs to contract or secrete through efferent neurons. Hence, option (d) is correct.

Explanation for the incorrect answer:

Option (a) is given as an afferent neuron only. They receive sensory information from different organs of the body and transmit to the central nervous system. They are present only in the nerves of the peripheral nervous system. So, it is an incorrect option.

Option (b) is given as efferent neurons only. They carry the processed information from the central nervous system to the peripheral nervous system in response to the afferent stimulus. So, it is an incorrect option.

Option (c) is given as dendrites. They are the branched protoplasmic extensions. They carry the electrical impulse to the cell body for the proper functioning of the cell. So, it is an incorrect option.

Option (e) is given as neuron cell bodies and neuroglia. The neuron cell bodies and the neuroglia do not make up the composition of the nerves. So, it is an incorrect option.

Hence, options (a), (b), (c) and (e) are incorrect.