Neural controls --
Types of neurons
Neurons are classified-
On the basis of function. It is of two types:
(a) Afferent neurons Carry impulses from receptors to CNS.
They are sensory in nature.
The terminals of dendrites become modified form receptors.
(b) Efferent neurons Carry impulses from CNS to effectors like muscles
or glands.
They are motor in nature.
The axon terminals come in contact with the motor end plate to form neuromuscular junction.
(i) On the basis of structure : It is of five types:
(a) Unipolar neurons
When neuron has only one process, i.e., one axon extends from the cell body, e.g., in embryonic stages
(b) Pseudounipolar neurons
When one process arises from the cell body and then divides into two i.e, axon and dendrite, e.g., dorsal root ganglion of spinal nerves
(c) Bipolar neurons
When one axon and one dendrite come out from the soma, e.g., retina of eye.
(d) Multipolar neurons When the axon and several dendrites extend from the soma, e.g., cerebral cortex.
(e) Non-polar neurons
When all processes of soma are equal and nerve impulse can be conducted in any direction, e.g. neurons of coelenterates.
