The process of breaking down the complex food substance into simpler particles which can be easily absorbed into the bloodstream is termed as Digestion.
In this process, various mechanical and biochemical processes are involved. The human digestive system is mainly composed of the alimentary canal and other associated glands. Mouth is situated at the anterior part whereas anus is situated at the posterior part of the body. The alimentary canal is divided into five main parts- mouth, esophagus, stomach, small intestine, and lastly large intestine.
Process of Digestion
In general, there are three separate stages of digestion:
Oral stage of digestion
The mechanism of digestion takes place with the chewing of food to breaks the food molecules into the minute particles and finally get mixed with the saliva. Saliva is the type of liquid that is secreted by the salivary glands. These salivary glands consist of salivary amylase which is an enzyme that begins the digestion of starch. The soft mass of food molecules, known as a bolus if formed and traveled to the esophagus and within the stomach with the help of peristalsis.
Gastric stage of digestion
The gastric juices present in the stomach begins to digest the protein molecules into smaller particles. The gastric juice contains pepsin and hydrochloric acid plays an important role in preventing food-borne illness as it kills any bacteria or viruses that may have been present in the food. During the protein digestion, the mechanical mixing happens with the help of peristalsis. This allows the food to get mixed with the digestive enzymes.
Intestinal stage of digestion
The molecules that have been discharged from the digested food including nutrients and water pass through the walls of the small intestine, enter the bloodstream and travel to various parts of the body where they can be used to repair and build.
The unabsorbed and undigested food molecules are moved to the large intestine and are stored in the rectum until it is removed by the body through a bowel movement.
Disorders of Digestive System
- Jaundice: In this. The liver gets affected, skin and eyes turn yellow due to the deposit of bile pigment.
- Vomiting: It is the ejection of stomach contents through the mouth and controlled by the center in the medulla oblongata.
- Diarrhea: It is the abnormal bowel movement and the fecal discharge with more liquidity, which leads to dehydration.
- Constipation: A condition in which the feces are clutched within the rectum due to an irregular bowel movement.
- Indigestion: A pain or discomfort in the stomach which is caused when food is not digested properly resulting in the feeling of fullness. Indigestion is mainly caused due to inadequate enzyme secretion, food poisoning, anxiety, overeating and eating spicy foods.
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