Question

Distinguish between afferent and efferent neurons.

Answer 1

Hint: Sensory neurons are also known as a receptor or afferent neurons, whereas motor neurons are also known as an effector or efferent neurons. Interneurons are present in the central nervous system and occur between the sensory and motor neurons for distant transmission of impulses

Complete answer:
Based on functions, neurons are of the following three types:
a) Sensory neurons: They are also known as a receptor or afferent neurons. These connect sense organs with the central nervous system.
b) Motor neurons: They are also known as an effector or efferent neurons. These connect the central nervous system to the effectors.
c) Interneurons: Also called a connector, relaying or adjustor neurons. These are present in the central nervous system and occur between the sensory and motor neurons for distant transmission of impulses.
Difference between afferent and efferent neurons are:

Afferent neurons	Efferent neurons
They carry sensory impulses towards the CNS.	They carry motor impulses away from the CNS.
They have short axons.	They have long axons.
They are unipolar.	They are multipolar.
The cell body is situated in the dorsal root of the ganglion of the spinal cord.	The cell body is situated in the ventral root of the ganglion of the spinal cord.

Note: Based on the number of axons and dendrites neurons are of three types:
i)Unipolar neurons: These have a single process arising from cyton. E.g. early embryos of invertebrates and vertebrates.
ii) Bipolar neurons: These neurons have only two processes, an axon at one end and a dendrite at another end. E.g. retina of the eye, olfactory epithelium and cochlear and vestibular ganglia.
iii) Multipolar neuron: These neurons have several dendrites and one axon. E.g. cerebral cortex.