Digestive system explained

We need food to fuel our bodies for energy, growth and repair. The digestive system converts the foods we eat into their simplest forms, like glucose (sugars), amino acids (that make up protein) or fatty acids (that make up fats). The broken-down food is then absorbed into the bloodstream from the small intestine and the nutrients are carried to each cell in the body.

The digestive tract begins at the mouth and ends at the anus. It is like a long muscular tube, up to 10 meters long, with digestive organs attached along the way. A large reservoir of microbes, such as bacteria, live within the large intestine and, to a lesser degree, in vthe rest of the digestive system.

These bacteria play an important role in healthy digestion.

The exact types of bacteria are particular to each person#

Other factors that influence the type of bacteria in your digestive system include where you live in the world, what health conditions you have and what medications you have received.

Digestion begins in the mouth#

The food is ground up by the teeth and moistened with saliva to make it easy to swallow. Saliva also has a special chemical, called an enzyme, which starts breaking down carbohydrates into sugars. Once swallowed, muscular contractions of the esophagus massage the ball of food down into the stomach.

The food passes through a sphincter, or small muscle ring, into the stomach.

Here it is mixed with gastric juices#

The stomach is a muscular bag and it churns the food to help break it down mechanically as well as chemically. The food is then squeezed through a second sphincter into the first part of the small intestine, called the duodenum. Once in the duodenum, the food is mixed with more digestive enzymes from the pancreas and bile from the liver.

Food is then squeezed into the lower parts of the small intestine, called the jejunum and the ileum. Nutrients are absorbed from the ileum, which is lined with millions of finger-like projections called villi. Each villus is connected to a mesh of capillaries.

This is how nutrients pass into the bloodstream#

The pancreas is one of the largest glands in the human body. As well as digestive juices, it secretes a hormone called insulin.

Insulin helps to regulate the amount of sugar in the blood#

Diabetes is a condition caused by problems with insulin production.

The liver has a number of different roles in the body, including: generation of glucose for short-term energy needs from other compounds like lactate and amino acids. Once all the nutrients have been absorbed, the waste is moved into the large intestine, or bowel. Water is removed and the waste (feces) is stored in the rectum.

It can then be passed out of the body through the anus. Some common problems include:

• ulcer – a hole in the mucous membrane lining the stomach or duodenum. The mouth
• esophagus The stomach The small intestine Pancreas Liver breaking down fats
• using bile stored in the gall bladder processing proteins
• carbohydrates filtering processing impurities drugs
• diarrhea heartburn – when the contents of the stomach back up into the esophagus

Where to get help#

Key Points#

• These bacteria play an important role in healthy digestion
• Diabetes is a condition caused by problems with insulin production
• Some common problems include: ulcer – a hole in the mucous membrane lining the stomach or duodenum