We eat food to live, and many of us live to eat too! Where this food goes and how exactly it is processed are necessary questions that we need to ask to remain healthy. This issue of Apollo Life presents to the readers manifold aspects of these two questions.
But first, let us look a bit closely at the gastrointestinal tract to get an overview of this amazing system which receives and processes the food we consume.
The human gastrointestinal tract mainly refers to the stomach and intestines. However, many specialists consider the mouth as the starting point and the anus as the end-point of the gastrointestinal tract for a comprehensive understanding of the process involved in the consumption, digestion and disposal of waste matter. The digestive tract or Gastro-Intestinal (GI) tract is the long passage that takes food from the mouth all the way through the stomach and the intestines, with wastes coming out of the anus. The sequence is mouth- esophagus- stomach- duodenum- small intestine- large intestine -rectum- anus. The entire gastrointestinal system is under hormonal control. The intake of food triggers off a huge number of hormonal actions. When the food is in the stomach, different hormones activate acid secretion, enzyme release etc. Nutrients from the GI tract are not processed on-site; they are taken to the liver to be broken down further, stored, or distributed. Organs such as the liver and the pancreas secrete enzymes used in the digestive process, and therefore are vital to the system. The liver, the gall bladder and the pancreas along with their ducts is collectively termed the biliary system.
Below are some organs that form the crux of the GI system. Like long lost relatives, we might have heard the names of some, but have forgotten what exactly they do, and where they are. Here’s a quick recap for memory’s sake:
- Oesophagus: Once food has been chewed and mixed with saliva in the mouth, it is swallowed and passed down the oesophagus, or the food pipe.
- Stomach: The stomach is a ‘j’-shaped organ, with two openings- the oesophageal and the duodenal. Its major functions include temporary storage of food, preliminary digestion with the mixing of pepsin, lipases, etc. It also controls the rate in which food enters the duodenum.
- Duodenum: The upper part of the small intestine is called the duodenum. It is shaped like a ‘C’ and its main function is to neutralise the acidic gastric contents (called ‘chyme’), and help further digestion.
- Small intestine: Apart from the duodenum, the small intestine consists of the jejunum and ileum. These two are coiled thoroughly and the junction between the two is not well-defined. The small intestine is the place where most of the chemical and mechanical digestion is carried out.
- Large intestine: This is the part of the body where faecal matter is formed. It removes water from the remainder of the digestive matter, and passes semi-solid faeces into the rectum so that they can be expelled from the body through the anus.
- Liver: This is the largest organ in the human body. It serves some of the most important tasks like storing iron, vitamin and trace elements, while producing bile and helping in the process of digestion.
- Pancreas: The pancreas consists mainly of exocrine glands. These glands secrete enzymes that aid in the digestion of food. The main enzymes produced are lipases, peptidases and amylases for digestion of fats, proteins and carbohydrates respectively.
The GI tract in an adult human male is about 20 feet long, making it a mechanism of great size and complexity.