Microbe Magic
schools.apc.ucc.ie
   

Explore Your Guts

Oesophagus Liver Gall Bladder Stomach Duodenum Duodenum Duodenum Small Intestine Large Intestine Large Intestine Rectum Pancreas Appendix Mesenteric Mesenteric Mesenteric Mesenteric Mesenteric Mesenteric

A large colour poster with this image and additional information is available free of charge.
Please email apc@ucc.ie with your request.

Your alimentary canal or gastrointestinal tract is the long muscular tube from the mouth to the anus approximately 8.3m long. Food is ingested in the mouth and is digested mechanically and with the help of enzymes as it passes along the alimentary canal. Nutrients are absorbed by the body and waste is excreted through the anus as faeces approximately 24 hours after a meal is consumed.

« Interact!
Now click on parts of the main image to find out more about how your digestive system works.

The mouth

The mouth receives food and prepares it for digestion. Chewing reduces the size of food pieces and mixes it with saliva which moistens the food making it easier to chew and swallow.

The Oesophagus

The oesophagus is the tube about 25cm//10 inches long that connects the mouth to the stomach. The muscles in the oesophagus push the food along in a process called peristalsis. If peristalsis is reversed vomiting occurs.

The Stomach

The stomach is a large sac-like organ which churns the food around and bathes it in a strong acid. This continues the breakdown of food and kills bacteria. The mixture of partly digested food and acid is called chyme. No nutrients are absorbed from the food while it is in the stomach. The following is a diagram of the stomach walls:

The Liver

The liver is the largest glandular organ in the body. The liver has many functions that include, but are not limited to the production of protein and cholesterol, the production of bile and clotting factors, the storage of sugar in the form of glycogen, and the breakdown of carbohydrates, fats, and proteins. The liver also breaks down and excretes many medications.

The Gall Bladder

The gall bladder stores bile which is made in the liver. It is a pear-shaped sac , dark green in colour because of the bile. Bile is green fluid produced by the liver and stored in the gallbladder, where it is released into the duodenum to aid in the digestion and absorption of fats

The Pancreas

The pancreas is a gland lying behind the stomach that creates insulin and pancreatic juice which contains enzymes used during digestion. The pancreas also releases insulin so that other body cells can use glucose (sugar) for energy.

The spleen

This organ is found on the left side of the abdomen, next to the stomach. It makes white blood cells that help fight infection and filters and cleanses the blood.

The Duodenum

The duodenum is the first part of the intestine and joins the stomach to the jejunum.. It is a c-shaped tube which curves around the pancreas and receives bile via the bile duct.

The Small Intestine

The small intestine is made up of the jejunum and the ileum.

The jejunum is the middle part of the small intestine. Here enzymes continue digestion of food.

The ileum is the last and longest part of the small intestine. Most of the absorption of the food occurs here. Finger-like projections called villi ensure that there is a large surface area for absorption. In fact, the surface is equivalent to the surface of a tennis court. The following is a diagram of the small intestinal walls:

The superior mesenteric artery and vein

The superior mesenteric artery supplies blood to the ileum and jejunum.
The superioer mesenteric vein drains the blood from the jejunum and ileum.

The Appendix

The appendix is a wormlike 'pouch' several inches long located near the top of the large intestine, in the lower right portion of the abdomen. The role the appendix plays in the human body is not known.

The Large Intestine

The large intestine is larger in diameter but shorter in length (about 1.5m) than the small intestine. Here water and some electrolytes like sodium are absorbed. Many microbes including Bifidobacterium. Lactobacillus, Acidophilus, E.coli and Klebsiella live here and help in the digestion process. The large intestine is made up of three distinct parts; the caecum, the colon and the rectum. The following is a diagram of the colon walls:

The Rectum

Unabsorbed food or waste material passes through the cecum (the appendix is connected to the cecum) into the ascending colon, across the transverse colon, and down the descending colon through the sigmoid colon to the rectum. 24 hours after the meal, the waste material reaches the rectum and is egested through the anus.