The Small Intestine

Even though digestions take place in different parts of the body, most of the digestion takes place in the small intestine.

The small intestine has a length of 6 meters in adult humans and it is the longest section of the digestion track in the body.

The small intestine gets its name as small because the large intestine is shorter, but it is fatter and therefore the small intestine, even though it is longer is still called “small.”

Major Organ of Digestion

The small intestine is part of the gastrointestinal tract or the GI tract and it runs from the pyloric sphincter to the ileocecal valve and then into the large intestine.

The small intestine is considered the major organ of the digestion and it is the organ that does most of the absorption of the nutrients.

Absorption is when the body takes something in. In our digestion, the body uses the pancreas, the gallbladder, the liver and the small intestine.

Pancreas and Liver

The pancreas is used to make sure that enzymes are made in the body that can stop acid that goes into the stomach.

The liver helps to make bile which is made of substances that are found in the gallbladder, waiting until it is needed, and the bile is made up of salts, pigments that are made by red blood cells from the liver (these are eliminated from the body as a solid).

Parts of the Small Intestine

The small intestine has different parts. The first part of it, 25 centimeters of it, is called the duodenum.

The duodenum is where acid mixes with digestive juices from the liver, pancreas and gallbladder, but these are not released inside the body unless the body needs these.

Small Intestine Hormones

There are four hormones that work through the small intestine and these are gastrin, secretin, cholecystokinin, and enterogastrone.

These hormones help the body to work the way that it should with the stomach and the small intestine playing a role in how the hormones are released into the body.

Parts of the Small Intestine

The duodenum is a U-shaped part of the small intestine that connects the stomach and the jejunum.

The jejunum is the middle part of the small intestine and it is about 2.5 meters long.

The last part, the ileum is the final section of the small intestine and it is around 5-6 meters long.

Muscles of the Small Intestine

The muscles of the small intestine are arranged left to right on the outside and on the inside of the muscles in a circle.

Nerve fibers are located in the small intestine and these helps to move food through the small intestine.

Mechanical and Chemical Digestion

There are two types of digestion that takes place in the small intestine, mechanical and chemical digestion.

With mechanical digestion, the food is broken down into small pieces.

With chemical digestion, the food is changed into smaller substances chemically.

Enzymes are used to help speed up the chemical reaction in the body so that the body can break down food such as starches.

The chemical reaction lets the starch be broken down to sugar.

Facts About the Small Intestine:

The small intestine breaks down food so that it can be absorbed inside the body.
The small intestine has thousands of villi, which are finger like structures.
The villi help the body to absorb food particles.
The process by which food is broken down so that the substances can be used in the cells of the body is called digestion.

What Did You Learn?

What are the three parts of the small intestine called? The three parts of the small intestine are the duodenum, the jejunum, and the ileum.
What happens when something is digested mechanically? When something is mechanically digested, it means that it is broken down into smaller pieces. The mouth helps with mechanical digestion by chewing the food into smaller pieces.
What happens when something is digested chemically? When something is digested chemically, it mixes with different chemicals that helps to speed up the digestion process.
What are the finger like structures found in the small intestine? The villi are the finger like structures that are found in the small intestine.
What is longer, the small intestine or the large intestine? The small intestine is larger. The large intestine is shorter, but it is fatter than the small intestine.

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