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The Human Digestive System

Updated on April 24, 2012

The Human Digestive System is capable of tremendous things, taking food and extracting nutrients separating them from the waste products. In this Hub I will break down each part of the digestive process and what happens at each process.

Oral Cavity

The oral cavity is where the start of the digestive system is located, the oral cavity is the opening to which the food and fluids are out into the body, the main purpose of the oral cavity is to intake food and chew the food down to smaller pieces to allow the food to be passed down to the parts of the system that break down food (the stomach) because the food is in smaller pieces the enzymes within the stomach and intestines are able to have an easier job of breaking down the carbohydrates, fats and proteins within the food.


The tongue is a very important part of the oral cavity too, the tongue is a muscle that allows food to be chewed between the upper and lower teeth, the tongue also aids in swallowing the food that has been chewed. The tongue also aids in negative pressure creation within the oral cavity which allows infants to suckle.


The oesophagus is the least complex part of the digestive systems tubes, it consists of stratified squamous epithelium which allows the oesophagus to digest foods that are rough edged and may cause damage when swallowing, the oesophagus doesn’t have any absorption which the purpose of this is to just send the food down to the part of the body that digests and uses the food, the oesophagus works by using peristaltic contractions which send the food down the tube into the stomach, the contractions are much like a ripple in water the contractions work together on each side of the oesophagus to send the food down effectively and as fast as possible.


The stomach is most probably the most known and recognised part of the digestive system and there is a reason for that, The human stomach is made of 5 layers of tissue which each have a set purpose, the stomach measures 12inches long and 6inches in size at its largest point and has the ability to hold up to 0.94litres of food at any one time. The cardiac sphincter prevents food from entering back into the oesophagus basically acting like a one way valve. The inner layer of the stomach called the mucosa which is where the digestive juices and stomach acid is produced. The second layer called the submucosa this layer is surround by a layer called the muscularis, this layer of muscle moves and mixes the contents that are within the stomach. The final two layers are called subserosa and the serosa is the wrapping for the stomach.


The pancreas is a gland that secrets digestive enzymes and hormones within the body. The pancreas is about 7inches long and 1.5inches wide in size. The pancreas is located beneath the stomach and is connected to the small intestine via the duodenum. The pancreas completes the job of breaking down carbohydrates, proteins and fats using the juices of the pancreas and the small intestine.

Small Intestine

The small intestine is the part of the digestive system that is responsible for absorbing most of the nutrients from our food. By the time the food has reached the small intestine it has been mechanically broken down by the stomach into a liquid, which then flows in the small intestine which is then picked up by small blood vessels within the small intestine. The vessels then carry the blood to all areas of the body with the nutrients. A meal can take from 3-6 hours to go from one end of the intestine to the other.

Large Intestine

The large intestine reabsorbs water and maintains the fluid balance within the body, it also absorbs certain vitamins (insert them here), processes undigested material which is also known as fibre and stores waste before it is eliminated by the rectum. The large intestine is around 1.5m long and consists of the caecum, appendix, colon and the rectum which are controlled by abdominal activity.


The rectums main function is to act as a temporary storage area for waste material before it is eliminated from the body by the anal canal. Waste material contains digestive juices, bacteria and fibre is stored in this area until it is pushed out by bowel movement.


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