My Article no 3

                                                                                COORDINATION AND CONTROL

The tissues and organs in the bodies of multicellular organisms don not work independently of each other. They work together performing their many tasks as the needs of the whole body. This means that these activities are coordinated. Coordination also enables the organism to respond to happenings in the world around it.

Our familiar example of coordination the way in which muscles work together during movement. When a boy runs to catch ball, he uses hundreds of muscles to move his arms, legs and back. His nervous system uses information from his sense organs and coordinates these muscles. Due to this coordination, the muscles contract in the correct sequence, power and length of time. But that is not all. Such activities involve many other kinds of coordination. For example; breathing and heartbeat rates are increased, blood pressure is adjusted, and extra heat is removed fast from the body.

How does it happen? Life activities are controlled and coordinated i.e. body works as one unit, in which its different organs and system cooperate and work in harmony with each other.

TYPES OF COORDINAITON

There are two types of coordination in organisms;

1.       Nervous coordination brought about by nervous system and

2.       Chemical coordination brought about endocrine system

Animals have both the nervous and chemical coordination system in their bodies while plants and other organisms have only chemical coordination.

Coordination Action

A coordinated action has five components.

1.       Stimuli

What happens when we touch a snail? We might have seen the flowers of sunflower plant moving towards the sun.  What could be the reason for all this? Touch, light etc. Are factors that can bring about certain responses in living organisms. These factors are called stimuli. We can define a stimulus as any change in environment (external and internal), which can provoke a response in organism. More examples of stimuli are heat, cold, pressure, sound waves, presence of chemicals, microbial infections etc.

2.       Receptors

Stimuli are detected by special organs, tissues or cells of body. For example sound waves are detected by ears, light is detected by eyes, chemicals in air are detected by nose and so on. The organs, tissues or cells which are specifically built to detect particular type of stimuli are called receptors.