The structure of the Gastro Intestinal Tract (GIT) begins with the mouth which is lined with mucus membrane and contains teeth with which to chew and break up the food. The tongue helps move food and liquid into the esophagus and the salivary glands produce the enzyme amylase to breakdown starches and liquefy food making it easier to swallow. The pharynx is situated at the back of the mouth which is the section of the throat between the skull and the esophagus which further helps to propel food into the esophagus.
The esophagus is a muscular tube located near the windpipe, through which food passes from the pharynx into the stomach using a series of peristaltic movements. The food then passes into the stomach which is a hollow container where the food is held whilst it is being mixed with enzymes secreted by the stomach to further breakdown the food ready to be released into the small intestines.
The small intestines is a 22 feet long muscular tube made up of three segments, the duodenum which is responsible for the final breakdown of food and the jejunum and Ileum which work together to absorb the nutrients into the blood stream, using gastric juices such as insulin from the pancreas and bile from the liver. What starts as a semi solid consistency mixed with water begins to change its consistency to become more liqufied. Once all the nutrients have been absorbed the residue is then passed into the large intestines or colon which is a six feet long muscular tube connected to the small intestine and rectum. It consists of four different parts, the ascending or right colon, transverse (across) colon, the descending colon and the sigmoid colon which connects to the rectum.
The large intestines perform the highly specialized task of processing waste making it simple and convenient to empty the bowel. It assists waste to move through it by a second series of peristaltic movements. First as liquid, it is then converted into a solid form by reducing the liquid content by a process of osmosis. The solidified stool is then stored in the sigmoid colon until it empties into the rectum. It takes approximately 36 hours for faeces to work its way through the colon mostly consisting of food and bacteria.
The rectum which means ‘straight’ is 8 inches in length and responsible for receiving the stool from the sigmoid colon. It connects the colon with the anus and it is part of the GIT which through a series of nervous impulses to the brain alerts the rectum when it is ready to be evacuated. If evacuation is not convenient the sensation goes away temporarily.
The Gastro Intestinal Tract terminates at the anus which is the smallest part measuring 2”. The lining of the upper anus is programmed to detect the rectal content and lets you know whether the content is gas, liquid or solid. It is surrounded by a sphincter muscle responsible for keeping you continent when you are asleep or when you are unaware of the presence of stool.