Coordination And Control-Inrtoduction:

In organisms, various organs and systems participate and play their role as and when required. Every organ of an organism does not work continuously except the heart, brain and lungs, which according to their role in the body are required to work 24 hours a day.

You can imagine what a bizarre scene it would present, if you want to lift an object in which you are required to use your both hands but your hand do not follow your command or if one of your hand is trying to lift it and the other hand is opposing it at the same time, their would surely be a chaotic situation.

For proper functioning of the body of an organisms, it is therefore, necessary that various organ and system work only when required, do their right type of job and also should not overdo or under do their jobs, when more than one organs are involved in an activity all the organs should operate in a sequence for the successful accomplishment of that particular function. All these attributes of physiology can be achieved when the body works as one unit, in which its different organs and systems cooperate and work in harmony with each other, i.e. its various functions are coordinated. Their coordination can ensure the successful existence of the organisms.

In animals co-ordination is produced by two systems.

(i)                Nervous system

(ii)              Endocrine system or chemical coordination

In both types of co-ordinations, the change (stimulus), whether external or internal is perceived by special organs which are called sensory organs. Any activity of an organism, when analyzed can be found to consist of responses. A response is a reaction to some action which takes the form of a stimulus. The stimuli are changes in the environment both external and internal. The change in the environment already mentioned is perceived/felt by special organs of the body, which are specialized to receive efficiently a particular type of stimulus. As for example the sound waves are received by ears. The stimuli of light are received by eyes; the stimuli of smell are received by nose, so on and so forth. Those organs which are specifically build to receive particular type of stimuli are called sensory organs or receptors.

The information about the stimuli is then conveyed to the brain or spinal cord through neurons or nerves and to the endocrine glands through the blood. The brain or spinal cord and endocrine glands play their role according to the stimuli. The former sending message about the action or response to be made by particular organs. The later by secreting hormones which are poured into blood and transported to the special organs or target organs which produce the response. The organs producing particular responses are known as effectors organs, which are muscles and glands.