Human Digestive System Essay

You are what you eat, foods are the main founder of nutrients for growth. Without proper diet, human cannot grow up normally. In order to get the nutrients from foods, process of digestion need to be been through. In human digestive system includes a few parts which carry out different processes, such as mouth, esophagus, stomach, small and large intestine and rectum. There are six steps of food digestion in human body which are food consumption, peristalsis, secretion, digestion, absorption and elimination (Marieb, 2004). By slowly proceeding through all these steps one by one, foods are eventually been broken down into small and simple particles of nutrients which absorbed by human body and the waste (which cannot be absorbed) to be eliminated (refer to Figure 1 in Appendix 1). Firstly, the human digestive process begins with ingestion. Ingestion involves the intake of food into the mouth where the food is chewed into smaller pieces and mixed with saliva. Saliva is a liquid that contains enzymes such as lysozyme (which kills bacteria) and salivary amylase (beginner of digestion in starch). Once the food has been chewed into a small soft mass called bolus, deglutition (swallowing) process takes place. The tongue helps to move and push the bolus into the back of throat then enters the esophagus (a hollow muscular passage that allows food bolus to travel from throat to the stomach). The second step is peristalsis. Food bolus does not just free-fall into stomach yet, as a