A multicellualr organism is made up of group of cells that forms tissues. Every organism constitutes several systems which has many organs in it. These organs and systems cannot work independently. In order to maintain the normal functioning of the body, the different organs must work in coordination with each other. For example, if someone is running, the person will have to perform muscular action, muscles need more oxygen and blood supply, heat will be released through skin in the form of sweating. In this way, the muscular system, respiratory, circulatory and excretory systems along with nervous system all work together to perform the function.