||looking up insect nervous system I come across this wonderful page on insect anatomy. link
I also come across this great page on eyes. link and this great little nugget about different cells of insects here. There are 3 types:
Neurons are usually divided into three categories, depending on their function within the nervous system:
1. Afferent (sensory) neurons -- these bipolar or multipolar cells have dendrites that are associated with sense organs or receptors. They always carry information toward the central nervous system.
2. Efferent (motor) neurons -- unipolar cells that conduct signals away from the central nervous system and stimulate responses in muscles and glands.
3. Internuncial (association) neurons -- unipolar cells (often with several collaterals and/or branching axons) that conduct signals within the central nervous system.
Individual nerve cells connect with one another through special junctions, called synapses. When a nerve impulse reaches the synapse, it releases a chemical messenger (neurotransmitter substance) that diffuses across the synapse and triggers a new impulse in the dendrite(s) of one or more connecting neurons. Acetylcholine, 5-hydroxytryptamine, dopamine, and noradrenaline are examples of neurotransmitters found in both vertebrate and invertebrate nervous systems.
Nerve cells are typically found grouped in bundles. A nerve is simply a bundle of dendrites or axons that serve the same part of the body. A ganglion is a dense cluster of interconnected neurons that process sensory information or control motor outputs.