NERVOUS SYSTEM OF INSECTS

• The nervous system consists of elongated cells which form the physiologically functional elements that are known as neurons. These neurons carry the information in the form of electrical impulses.

Classification of neurons:

A) Based on their structure:

1. Unipolar/monopolar: Have a single axon without collaterals and dendrites.
2. Bipolar: Have either collaterals and dendrites in addition to axon
3. Multipolar: Neurons have an axon with several collaterals and dendrites.

B) Based on function: 3 kinds of neurons.

1. Sensory/afferent neurons: Present just beneath the integument and associated with sensory organs. Carry impulses from sense organs to the central nervous system.

2. Motor / efferent neurons: Always unipolar/monopolar carry impulses from the central nervous system to the organs.

3. Association / internuncial neurons: Associated between sensory and motor neurons, usually present in ganglia, consists of axons of sensory neurons and soma of motor neurons. The transverse commissures are also formed with these neurons. The points at which neurons receive information from or convey it to another neuron are known as synapses.