Response and Coordination in Plant and Animals!
Our body is made up of billions of cells that get organized into different tissues.
Different tissues constitute organs, and different organs constitute systems such as the digestive, respiratory and circulatory systems.
In order to perform a particular function the component organs of each system depend on each other and work in harmony.
In the absence of such working in harmony, an organism cannot do many things that it normally does.
For example, when we run, our muscles require greater energy, which can be produced when there is a greater supply of oxygen. To increase the oxygen supply, the rate of breathing increases. When we stop running, our muscles do not need so much energy.
Consequently, there is no need for extra oxygen and the rate of breathing comes down to the normal level. All these activities are coordinated and well organized. The working together of various systems in the body is called coordination.
Response and Coordination in Plants and Animals:
The ability of an organism to detect changes and make appropriate responses is called sensitivity. Anything to which an organism responds and reacts is called a stimulus. In animals the responses are quicker and more obvious. Unicellular animals respond to stimuli either by moving towards them or away from them.
In multicellular animals, the process of responding to stimuli is different. The responses occur within seconds, but through a complex network of communication which involves several life processes like movement, locomotion, transport, respiration, etc. For example, when you step out in bright sunlight, you partly close your eyes to keep out the bright light. You may start sweating as the temperature rises. These are coordinated responses to stimuli.
Response and coordination in animals involve the sense organs, nervous system and chemical messengers called hormones.
Plants also react to specific environmental conditions. However, they have no nervous system and their responses are in the form of slow modified growth or movements called turgor movements, caused due to the distension (swelling) of cells. Let us first examine the phenomena of response and coordination in plants.