Co-ordination between Organs and Systems to keep the body fit:
The body of man and other animals is formed in harmonization with some systems. A particular structure is again formed of some related organs. Each of these organs has particular arrangement and functions.
An organ is a part of animal body formed by the combination of one or more than one type of tissues performing a particular function or functions. Example: Eye, ear, stomach, heart, liver, kidney, testis, ovary etc.
System is formed in combination of more than one related organs. Each system performs the particular functions separately. Example: Digestive system, blood circulatory system, excretory system, reproductive system, nervous system, etc.
There exists coordination among the functions of the organs of a system. Each system works separately and each has its own specific functions. For example, the function of the digestive system is mainly intake of food, digestion of food, absorption of digested food, and temporary storage and excretion of undigested food. Of this system the digestive glands named salivary glands; liver and pancreas take part in digestion by secreting various digestive enzymes. In this system, the pharynx and oesophagus take part in food intake, stomach and duodenum in digestion of food, ileum both in digestion and absorption of food and the rectum in storing the undigested food. In any living beings, all these systems are interrelated.
So, a system works properly only when each of the component organ of that particular system function properly and systematically. Again, through the coordinated work of different systems, living beings do their regular activities. In case of all higher animals, nervous system and endocrine system together control and conduct the works of all organs, i.e. all systems to keep the body healthy and fit.