The functioning of the human body is credited to the collective work of the organ systems, and the digestive system is one of them. It comprises various organs that aid in the digestion of food and assimilation of nutrients. So, what is digestion? It is the process of breaking down complex food particles, both mechanically and chemically, into simpler forms of nutrients, which can be readily used by the body.
Putting it in simple words, the organs of the digestive system are responsible for release of energy, which is crucial for every living cell and tissue to function normally. Also, the digestive system is responsible for distribution of the nutrients and wastes in the body. And, when we say parts of the digestive system, it basically comprises the alimentary canal and the associated digestive organs. Any abnormalities in the parts or organs may lead to digestive system disorders and/or diseases.
Parts of the Digestive System and their Functions
The anatomy of the digestive system is studied in detail in order to understand its parts as well as their respective functions. The major part of the gastrointestinal system is the alimentary canal (also called gastrointestinal tract or digestive tract), a hollow tube like structure that extends from the mouth to the end- the anus. Mentioned below is a list of the different parts of the digestive system, which are involved in the digestion process:
The organ responsible for initiating digestion is the mouth. While in the mouth, the teeth masticates the food into smaller pieces, which are mixed with the saliva secreted by the salivary glands. The saliva contains amylase and other enzymes that together bring about partial digestion of the food.
Also commonly known as throat, the pharynx is a small portion of the digestive system located between the mouth and the esophagus (at the back of the nose). From the mouth, the partially digested food is pushed, swallowed, and moved to the esophagus via the pharynx.
The food from the pharynx is passed through the esophagus and then into stomach by peristaltic movements (slow rhythmic contraction and relaxation of the esophageal muscles). At the distal end of the esophagus, lies the lower esophageal sphincter (LES) that prevents food from the stomach to return into the esophagus.
The partly digested food particles from the esophagus are received by the stomach, where they are stored and digested. The stomach secretes acidic digestive juices (about 2.8 liters daily) for chemical break down of the food particles. The thick muscles of the stomach also churn the food to allow proper mixing with the digestive juices.
Once the food is mixed and digested in the stomach, it is transferred to the small intestine (about 20 feet long) for further digestion. Comprising the duodenum, jejunum, and ileum, the small intestine is the part of digestive system that absorbs nutrients from the food being digested. The digestive enzymes secreted by the lining of the small intestine along with bile (produced by the liver) and pancreatic enzymes altogether aid in further digestion of food.
Liver and Pancreas
The liver is a vital organ that secretes bile juice for digestion of fats. Bile from the liver is stored in the gallbladder (a small sac like structure) and then released to the small intestine. Likewise, the pancreas is also an associated digestive organ that produces a mixture of enzymes for digestion of carbohydrates, fats, and proteins.
The large intestine (about 5 feet long) consists of different parts- cecum, colon, appendix, and rectum. Food from the small intestine passes through the cecum portion, wherein water and electrolytes are absorbed. The undigested leftover food (or waste) is transferred to the ascending colon first, then to the transverse colon and sigmoid colon. The waste from the sigmoid colon is moved to the rectum, where it is stored till the time of bowel movement. Finally, the waste is passed as stool through the anus.
Overview of the Digestion Process
After chewing of food in the mouth, the partially digested food particles pass through the alimentary canal, which are further broken down into simpler forms with the help of enzymes secreted by the associated abdominal organs (liver and pancreas). The nutrients are absorbed by the villi located in the small intestinal walls, which are then released in the bloodstream for distribution to the different parts of the body. The undigested food particles from the small intestine are passed to the large intestine for defecation.
One of the interesting facts about the digestive system of an adult human is that the GI tract measures about 30 feet in length. With this information about all the parts of the digestive system and how they help in digestion of foods, we hope you have cleared your doubts regarding it and the process of digestion.
Disclaimer: This article is for informative purposes only and does not in any way attempt to replace the advice offered by an expert on the subject.