How does the digestive system process food?

The digestive system processes food by breaking down large food molecules into simple nutrients such as proteins, carbohydrates and fat, which can be absorbed by the body to be used for growth, energy, and repair. Anything that isn’t used by the body is eliminated. The digestive system is made up of several organs, each of which plays an important role in the digestive process. 

Step-by-step process of how the digestive system processes food and the organs involved: 

1. Digestion starts with the ingestion of food. In the mouth, the teeth chew food into small pieces while the salivary glands produce saliva. Saliva contains the enzyme amylase, which breaks down starch in the food.  
2. The partially digested food enters the esophagus, a long tube that carries food from the mouth to the stomach by peristalsis. The lower esophageal sphincter, which is a ring of muscle located where the esophagus meets the stomach, prevents the stomach contents from going back up the esophagus.  
3. In the stomach, gastric acids break down the food further to facilitate digestion and absorption of vitamins and minerals. Two digestive enzymes, pepsin and trypsin, which are also produced in the stomach, help to break down proteins. From here the food enters the small intestine. 
4. Most of the chemical digestion of carbohydrates, proteins, and fats takes place in the small intestine helped by enzymes produced in the pancreas and liver. The small intestine of an adult is about 5 meters long and made up of several folds and bends, which increase its surface area tremendously. This large surface area helps vitamins, proteins, sugars, fatty acids, and minerals pass through the intestinal walls into the bloodstream more easily. The blood stream transports the digested nutrients to every tissue in the body to be converted into energy by various cells. 
5. After all the nutrients have been absorbed, the waste that’s not needed by the body is moved into the large intestine, or bowel. Excess water is removed and the waste is stored in the rectum to be eliminated from the body through the anus.