CONTROL AND COORDINATION
All living organisms including plants and animals respond and react to environmental factors or stimuli. There is necessity to
develop some system for control & coordination of various body organs. In multicellular organisms, specialized tissue is
used for control & coordination activities. Control & coordination in animals are provided by nervous & muscular tissues.
Chemical coordination is seen in both plants and animals.
It is the system of conducting tissues that receives the stimulus and transmits it to other parts of the body forming a
-The nervous system comprise of – Neurons, Nerves and Nervous organs which controls, link & coordinate activities
of different organs of the body.
-Vertebrate Nervous System consists of Three parts
1. Central Nervous System (CNS): Includes Brain & Spinal cord.
2. Peripheral Nervous System (PNS): Includes Peripheral Nerves (Nerves which originate from CNS i.e. Brain &
3. Autonomic Nervous System (ANS): Includes Autonomic Nerves (Nerves which originate from peripheral
nerves & spinal nerves).
Function of Nervous system:-
1. It regulates involuntary action (Action which are not controlled by our Will).
2. It controls and coordinates voluntary muscular activities.
3. It enables us to think reason & remember.
4. It controls all reflex actions in our body thus protecting it from harm.
RECEPTER: it is a cell or group of cells specialized to detect particular stimulus and to initiate the transmission of impulse via
the sensory nerves.
UNIT OF NERVOUS SYSTEM: NERVE CELLS/ NEURONS:
Neurons are the longest cell of animal body.
Neuron does not divide after its formation because of longer length and lack of centriole.
About 12 billion neurons are in human body. The highest number of nerves cells is found at the time of our birth.