- Nervous System in arthropoda:
The arthropod nervous system consists of
a dorsal brain and a ventral, ganglionated
longitudinal nerve cord (primitively paired)
from which lateral nerves extend in each
segment. The system is similar to that of
annelid worms, from which arthropods may
have evolved. - Nervous System in Echinoderm: The
echinoderm have a very simple nervous
system, they lack a brain and many other
common sensory organs, like eyes.
Echinoderms do not have a central brain.
Echinoderms all have a network of nerves called
nerve plexus. These nerves run intertwined
under the surface of an Echinoderm’s skin.
Although the echinoderms do not have many
well-defined sensory inputs, they are sensitive
to touch, light, temperature, orientation and the
status of water around them.
Sense is caused by sensitivity in the tube feet
of Echinoderms which line the undersides of
their bodies and eye spots located throughout
the body. The eye spots each consist of a mass
of oculi, consisting of pigmented epithelial
cells that respond to light intensity, and are
lined with sensory cells in between them. Each
oculus is covered by a cuticle that both protects
them through its thickness and acts as a lens
with its transparency.
9. Nervous System in chordates: Dorsal nerve
cord is another feature the chordates share.
This is a hollow nerve cord that is towards the
back compared to the notochord. In animals
that have a backbone (vertebrates) this dorsal
nerve cord becomes the brain and spinal cord.
Function of Nervous system:- The stimuli or impulses are carried to CNS
from
muscles and vice versa. - Co-ordinates various organ systems.
- It stimulates and inhibits the activities of
muscles,
glands and viscera. - It helps to maintain the homeostatic condition.
- Forms and retains memory.
- Conducts information and message.
Human nervous system
The study of nervous system is called
neurology.
Human nervous system is broadly divided into
central nervous system and peripheral nervous
system.