The gastrointestinal system or GI system is the body system responsible for handling all the nutrition that a person puts in their body. “Gastrointestinal” is broken down into two parts: gastro-, which is from the Greek gaster- or gastr-, meaningstomach,’ and intestine from late Middle English, from Latin intestinum, of intestines, from intus meaning ‘within.’ There is a lot to the GI system in terms of structure and function.

But the overall purpose is to convert or breakdown the food we eat into sub products that can be used by the body for various functions. Specifically, the macronutrients (type of food required in large amounts in the diet) or carbohydrates, proteins and fats; and the micronutrients (the substances required in trace amounts for the normal growth and development of the body) or vitamins and minerals enter the body through the GI system.

The GI system starts at the mouth, then continues through the esophagus, stomach, small intestine, large intestine, rectum then anus. The GI system is fifth in my hierarchy of body systems coming after the respiratory, cardiovascular, musculoskeletal and neurological systems.

The mouth is responsible for starting the digestion process by chewing food as well as releasing saliva from the salivary glands. Saliva helps moisten the food making it easy to swallow. Saliva also has enzymes that begin to digest or break down food.

The esophagus is the tube which carries the food from the mouth to the stomach. The stomach plays a big role in the digestion of food. It holds the food and mixes it with acid and digestive enzymes that continue to break down food into a liquid or paste.

From the stomach, the digested food enters the small intestine which has three sections, the duodenum, jejunum and ileum. The first section is the duodenum where bile from the gallbladder and digestive enzymes from the pancreas enter the small intestine to aid in the digestion of fats, carbohydrates and proteins. The duodenum is also where absorption of micronutrients begins. The jejunum and ileum are mostly responsible for the absorption of macronutrients or carbohydrates, fats and proteins. Once absorbed the micronutrients and macronutrients or “macros” are transported to the liver to be further processed and packaged to be delivered to the body. The liver is an extremely important organ or specialized body structure and deserves special attention in a later article.

The remaining digested food is moved along to the colon where water and some nutrients and electrolytes are removed. The remaining material moves through the colon and is stored in the rectum to eventually leave the body through the anus.

So that’s the nuts and bolts of how we get nutrients into the body. This is an important part of making the body move. The body requires fuel just like your car. We measure fuel for the body in calories. A calorie is a unit of energy used to express the nutritional value of food, equivalent to the heat energy needed to raise the temperature of one kilogram of water by one degree centigrade.

Without fuel or calories, the body just won’t work. Give it too much fuel and the body will store this as fat. Your fat stores will be converted into fuel for the body when you are not taking in enough calories.

There are several things a person can do to help the GI system. Eating a clean diet with a good balance of carbohydrates, fats and proteins is one. Limiting the number of chemicals consumed that are not actually food or used by the body is another. Taking in a sufficient amount of water as well as fiber is also beneficial. Taking in a sufficient amount of calories is also beneficial for the body. Another thing that is overlooked is regular exercise as this promotes motility or the movement of food through the GI tract or system.

Most people have a GI system that functions pretty well. As you can imagine with all the various parts there are several ways the GI system can malfunction. We will likely cover a few of them in another article. But for now, if you have any questions feel free to ask.

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