Respiratory System
The body needs a continual supply of oxygen. In addition, the body also needs some means of disposing of the waste carbon dioxide produced by the body cells. Respiratory system fulfills both these requirements.
Digestive System
Energy is essential to maintain such vital functions and processes as breathing, blood circulation and brain function. It is derived from foodstuffs but food cannot be utilised by the tissues until it has been broken down to smaller simpler components through the process of digestion.
The digestive system is composed of the alimentary tract and accessory organs which contribute their secretion to the tract. The digestion begins in the mouth and ends in the bowel. The passage from the mouth to the rectum is about 9 metres in length.
The organs of this system are: Mouth, Salivary Glands, Aesophagus, Stomach, Duodenum, Small Intestine, Large Intestine (Colon).