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The Process of Digestion

The digestive system present in human body enables the body to process the food, extract the required nutrients from it and remove the waste from the body. The digestion of food is the first step in the process of digestion which is followed by absorption and assimilation process. The journey of digestion involves several body parts and organs of human beings. The systematic process of digestion is discussed along with the structure and function of each of the structures involved in the process of digestion.

The Mouth

The first step of digestion process starts with the mouth. The sight, smell or sense of food results in the secretion of saliva in the mouth of the human beings through the salivary glands present in the mouth. The process of receiving food by the mouth is called ingestion. The mouth or oral cavity is formed by the boundaries of lips, cheeks, palate and floor of the mouth. It contains teeth and tongue which helps in the process of digestion. The food when enters into the mouth is grasped by the teeth and is supported by the tongue. The secretion of salivary glands includes chemicals in it. The chemicals in the saliva together with the help of teeth and tongue crush the food and prepare it for the next step of digestion (Chiras, 2011).


The oesophagus is a tube like structure that connects the pharynx located in the neck of the human beings to the stomach. The function of oesophagus is to pass the food from the mouth to the stomach. It contracts and expands with the help of muscles in order to provide easy flow to the food. It usually remains wet with small amount of secretions so that the food can easily travel through and enters into the stomach (Hoffman, 2008).


The stomach is present below the diaphragm and in the upper level of abdominal cavity. The boundary walls of stomach are formed by the muscles including oblique, longitudinal and circular muscles and the mucosa and sub mucosa. The food is temporarily stored in the stomach during the digestive process. In the stomach, the digestive enzymes act upon the food to allow further digestion of the food. The gastric juice secreted by the stomach consists of water, mineral salts, mucus, hydrochloric acid and enzymes. The stomach secretes HCl (Hydro Chloric acid) and pepsin which is an enzyme that helps in the breaking down of proteins (Kahle et al., 1993).

Small Intestine

The food passes from the stomach to the small intestine. The nutrition in the food is absorbed in the small intestine. The small intestine is divided into three parts. The first segment is the duodenum. The second is the jejunum and the third is the ileum.teh length of the small intestines is around 22 feet. The diameter of the small intestine is lesser as compared to the large intestine. The nutrients are absorbed into the small intestine and the after passing through the small intestine the food becomes almost ...
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