Today we are going to study about Coordination &
Homeostasis. First, We will give our attention to Coordination. Coordination is
a very important thing to living beings to continue their lives. Animals unlike
plants, have two different but related systems for coordination.
- 1 Nervous system
- 2 Endocrine system
Types of nervous organization of animals
• All multicellular animals except sponges
use a network of nerve cells to gather
information about the external
environment, process and integrate that information, and
to
issue signals to the muscles and glands.
• Unicellular
No nervous organization ,ability to respond to stimuli. Cell functions
as the receptor and
effecter.
• Multicellular
• Cnidaria – Development of nerve cells.
Presence of a nerve net composed of multipolar
neurons, synapses. Conduction tracts in sea anemones. Development of
receptors.
• Platyhelminthes – longitudinal solid nerve
cords, organized from a nerve ring or
pair of
cerebral ganglion in the anterior region of the body - cephalization.
Development of
receptors. E.g., eyespots, sensory cells.
• Annelids
Cerebral ganglia, double ventral nerve cord, ventral ganglia, giant
nerve fibers
in some. Receptors E.g., eyes and sensory cells.
• Athropoda – More developed nervous system than that of Annelids. Cerebral ganglion
present. Well developed receptor organs of various type. E.g., eyes, antenna, palps
• Mollusca – Well developed nervous system .Consists of ganglia and nerve fibers
Presence of Receptor organs. E.g., well developed eyes
• Echinodermata – Radial nerve cord & nerve net
• Chordates – Single, dorsal, hollow nerve cord. Anterior region enlarged to form the brain.
Complexity increased gradually. Highest complexity is in mammals.
