Digestion essentially occurs in a series of tubes such as the Oesophogus and Intestines as food passes through the body. A number of other organs contribute to digestion by providing enzymes for the breakdown of food.
- Mouth: The mouth is the starting point of digestion. Here the process of chewing starts to break down food and enzymes such as salivary lipase and amylase also start to chemically break down the food.
- Oesophagus: Once you swallow the food moves into the Oesophagus where continual waves of involuntary contraction push the food into the stomach.
- Stomach: The stomach has both a mechanical and a chemical function in digestion. The upper part of the smooth (involuntary) stomach muscle relaxes to allow a large volume of food to be stored. The lower muscle then contracts in a rhythmical manner in order to churn the food inside and mix it together with the gastric acid (mainly hydrochloric acid) and digestive enzymes Pepsin, Gelatinase and Gastric Amylase and Lipase which break it down further. The stomach must then empty its contents into the small intestine.
The Small Intestine: The small intestine is the part of the intestines where 90% of the digestion and absorption of food occurs, the other 10% taking place in the stomach and large intestine. The main function of the small intestine is absorption of nutrients and minerals from food. The large intestine: The main functions of the large intestine are to absorb water from the effluent as it passes through the large intestine, forming it into stool, and to become a “holding tank” until the stool is expelled from the body.