The Digestive System

The Digestive System

The human digestive system is so uniquely constructed that it is able to perform the important role of converting digested food into energy that you need to survive and at the same time package residue to be disposed as a waste. The digestive system is also called the food or alimentary canal or GI tract (gastrointestinal tract) and it starts from the mouth and ends at the anus. This article will help you understand what parts are involved in the system as well as the functions that they play. Read on to understand this complex system.


The start of the digestive tract is the mouth. In fact, when you take the first food bite, digestion starts here. The food is broken down into small pieces by chewing so that they are digested more easily. Saliva also mixes with the food which signals the start of breaking down the food into a form that your body will absorb and use.


The esophagus is found in the throat close to the trachea. When you swallow the food after chewing, it is received at the esophagus. It helps deliver the food to the stomach by a process called peristalsis is which involves muscular contractions.


The stomach is just a hollow organ which holds the food as it is being combined with enzymes which continue the digestion process. The stomach walls have cells that produce powerful enzymes and hydrochloric acid which help in breaking down the food further. After the food in the stomach is processed sufficiently, the food is then released into small intestines where its digestion continues further.

Small Intestine

The small intestine is composed of three sections namely the jejunum, the ileum and the duodenum. It is composed of muscular tubes which continue the further breakdown of food with the help of enzymes that are released by bile and pancreas. The food moves down the tube through peristalsis as it is mixed with pancreatic juice and bile. Pancreatic juice helps in the further digestion of the food while bile, produced by the gall balder, helps to digest fats. Digestion mainly takes place at the duodenum section of the stomach while absorption of food into the bloodstream happens at the ileum and jejunum.

The intestine is the main part of the digestive system as it is where the food gets to be absorbed into the blood stream. Motility is the more technical moniker of this process as it involves moving or even emptying food particles from a single part to the subsequent one. The process is so much dependent on the functioning of large network of nerves, muscles and hormones. If any of these has a problem, it can cause different conditions.

As food is still in the mall intestines, the absorption of nutrients takes place through the walls and right into the bloodstream. Whatever is left after absorption (mainly waste) go into the large intestines.


This secretes pancreatic juice into the duodenum, which is the first section of the small intestines. The enzymes digest proteins, carbohydrates and fats. It is also ate pancreas that insulin is made, which is secreted directly into your bloodstream. Insulin is main hormone that metabolizes sugar.


While the liver definitely has many functions, its leading one insofar as digestion is concerned is to process nutrients that are absorbed from small intestines. Bile is also produced from the liver and it digests fats. Additionally, the liver is said to be the chemical factory of the body. It takes raw materials that have been absorbed by the intestines and manufactures all the requisite chemicals that the body requires to function. Also, the liver neutralizes potentially harmful chemicals.


This stores as well as concentrate bile after which it releases it into duodenum to assist with absorption and digestion of fats.

Colon (large intestine)

Measuring 6 feet, this muscular tube joins the small intestines and the rectum. It is composed of cecum, the transverse colon, the ascending colon, the descending colon and lastly the sigmoid colon that joins to the rectum. Appendix refers to a small tube attaching to the cecum. Also known as the colon, the organ of the large intestine is one that is highly specialized and is responsible for waste processing so that it is convenient and easy to empty the bowels.

Stool is passed via the colon through the peristalsis process, first in liquid form and finally in solid state. As this stool is passing through the colon, any water it contains is removed .It is temporarily stored into the sigmoid colon awaiting a ‘mass movement’ which sees it emptied into the rectum. It can take up to 36 hours for the stool to pass through the colon. Mostly, the stool comprises bacteria and food debris. The bacteria perform many useful roles, like synthesizing certain vitamins, protecting against the harmful bacteria and processing food particles and waste products. After the descending colon is full of feces, the contents are emptied into the rectum in what is the beginning of the elimination process.


The rectum, which means straight in Latin, refers to a chamber connecting the anus and the colon and it measures 8 inches. The rectum is tasked with receiving the feces from the colon, letting an individual know that there are feces to be passed out and holding the feces until is evacuated. If anything like stool or gas goes into the rectum, message is sent to the brain by sensors. The brain will then decide if the contents can be evacuated or not. In case they are to be eliminated, the sphincter muscles relax while rectum contracts and the contents are disposed.


This is the last part of the gastrointestinal tract and it is a canal measuring 2 inches and consisting of the two anal sphincters and pelvic floor muscles. The upper anus lining is so specialized that it can detect rectal contents. It will enable you to know whether the rectal contents are in solid, liquid or gas form. The anus is surrounded by muscles that play a key role in allowing stool control. The pelvic floor muscles form an angle between anus and the rectum that stops the feces from going out when it is not yet their time. The internal sphincter, on the other hand, stays tight at all times except when feces enter the rectum. When there is an urge to go to the toilet, it is the external sphincter muscles that hold the feces until you get to the toilet, where it will relax to allow the contents to be released.