The human body is a complex system that consists of a number of organ systems working in sync together for the sustenance of life. Even if one of the organ systems is absent or is malfunctioning, then it can affect the entire body system. The human digestive system, also called the gastrointestinal tract or GI tract, is one such system whose main function is digestion. Food and drink, when consumed, need to be broken down into small parts so that the body is able to use them for nourishment and energy. Digestion begins in the mouth and ends in the small intestine. The food in the mouth is mixed with digestive juices, and is broken down into smaller molecules. It is then pushed into the stomach, where further digestion takes place. The digested food is assimilated in the blood and transported to the entire body.
Digestive System of the Human Body
If you observe the diagram of the digestive system, you will notice that it is made up of different organs that function together. With the help of the explanation provided, you can understand the working mechanism of this organ system.
The Mouth or Buccal Cavity
The mouth or the oral cavity is the starting point of the digestive system. The buccal cavity, has a set of 32 teeth, a tongue, and salivary glands. All these parts help in the chewing and breakdown of food. There are three types of salivary glands, categorized according to their placement in the mouth - parotid, submandibular and sublingual. The salivary glands release enzymes that partially digest the food in the mouth before it is passed to the stomach through the esophagus. There is also another part in the oral cavity in the throat, known as the pharynx. The pharynx is the common pipe for the esophagus and the trachea (also known as wind pipe). The main function of the pharynx is the passage of food and air to the respective organs.
The esophagus, which is also known as the gullet or food pipe, is a long narrow pipe that connects the mouth to the stomach. The primary function of this pipe is transportation of food and liquid from the mouth to the stomach. The chewed food is passed through the food pipe by the process of peristalsis. Peristalsis is a process which consists of rhythmic contractions of the muscles in the inner wall of the esophagus to push the food through the pipe into the stomach.
The Stomach and Pancreas
The next important organ of the human digestive system is the stomach, where the actual digestion takes place. The stomach is located on the left side of the body below the diaphragm and has a cardiac sphincter muscle at the opening. This muscle further pushes the bolus (chewed food) into the stomach from the gullet. Once all the bolus is transported, the muscle closes and the stomach begins its process of churning the food. Gastric juices and enzymes are released in the stomach which aid in the further digestion of the bolus. Hydrochloric acid is also released during the process of digestion which helps break the protein molecules into peptides. The stomach wall has an inner lining that secretes peritoneal fluid and mucus to protect the stomach cavity from erosion due to the presence of gastric juices and acid.
The pancreas is a small leaf-like gland located below the stomach. This exocrine gland secretes digestive enzymes (in the pancreatic fluid), through the duct into the small intestine to assist in the digestion of chyme (partly digested food). The primary purpose of this organ is the metabolism of carbohydrates, protein and lipids (or fats). The pancreas consist of tiny structures called the islets of Langerhans which secrete insulin for the additional function of maintaining the blood glucose levels.
The Liver and Gallbladder
The liver and gallbladder secrete enzymes for the complete assimilation of food. The liver, which is the largest gland in the body, also acts as a storehouse for glycogen, vitamins and minerals. The liver produces an enzyme called bile which metabolizes the fat and protein molecules into smaller molecules for easy digestion. The gallbladder is a tiny organ near the liver and is a part of the biliary system. The gallbladder acts as a storehouse for bile and also to increase its concentration. Together, the liver and the gallbladder help to expel urea and other toxic wastes from the body, through urine.
The Small and Large Intestine
While taking a look at the anatomy of the small intestine, it can be seen that the organ is a thin wire-like structure intertwined and connected to the large intestine. The last stage of digestion takes place in the small intestine where all the nutrients from the food are absorbed. The main function of the small intestine is the absorption of digested food. The digested food is then assimilated in the small intestine and the waste is passed on to the large intestine. A finger-like structure called appendix, which is a vestigial organ, is connected to the beginning of the large intestine (also referred to as cecum). The large intestine then expels the waste out of the body to the rectum. The rectum stores the undigested food or fecal matter to be dispelled from the body through the anus, which is the final part of the digestive system.
The digestive system carries out the vital function of providing nutrition to the body. It is hard to imagine what it would be like if this important system was missing. For proper digestive health it is essential to quit harmful vices like alcohol, smoking etc. Hence you must also be aware of the common diseases of the digestive system, so that you can prevent them from occurring and also seek medical attention if you are affected. Eat nutritious and stay healthy!