The gastrointestinal tract in humans begins at the mouth, continuing through the esophagus, stomach, small and large intestines. Taken as a whole, the GI tract is about 9 meters in length. There are many supporting organs as well, such as the liver, which helps by secreting enzymes that are necessary for the digestion of food.
The human GI tract can be divided into two halves, namely, the upper GI tract and the lower GI tract.
Upper Gastrointestinal tract
The upper GI consists of the following organs:
- The Mouth
It includes the teeth, tongue, and buccal mucous membranes containing the ends of the salivary glands that continue with the soft palate, floor of the mouth, and underside of the tongue. Mouth functions by chewing the food, constantly by the muscular action of the tongue, cheeks, teeth through the lower jaw and upper jaw.
- The pharynx
The pharynx is enclosed in the neck and throat which functions as part of both the digestive system and the respiratory system. It protects the food from entering the trachea and lungs.
- The Esophagus
A muscular tube-like structure that functions by carrying food to the stomach. Once the chewed food reaches the esophagus from the mouth, the action of swallowing becomes involuntary and is controlled by the esophagus.
- The Stomach
This is where most of the digestion takes place. The stomach is a J-shaped bag-like organ that stores the food temporarily, breaks it down, mixes and churns it with enzymes and other digestive fluids and finally, passes it along to the small intestine.
Lower Gastrointestinal tract
The lower GI consists of the following organs:
- Small intestine
The small intestine is a coiled thin tube, about 6 meters in length, where most of the absorption of nutrients takes place. Food is mixed with enzymes from the liver and the pancreas in the small intestine. The surfaces of the small intestine functions by absorbing the nutrients from the food into the bloodstream, which carries them to the rest of the body.
- Large Intestine
The large intestine, also known as the Colon, is a thick tubular organ wrapped around the small intestine. Its primary function is to process the waste products and absorb any remaining nutrient and water back into the system. The remaining waste is then sent to the rectum and discharged from the body as stool.
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