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Human Intestine

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What are Intestines?

The human body is a complex form of life made up of cells, tissues, organs, and organ systems where each of them works to complete the basic life processes. The life process includes growth, respiration, digestion, and excretion, where all of these processes are interrelated. 

The digestive system consists of the gastrointestinal tract and other organs. The gastrointestinal tract consists of the mouth, throat, oesophagus, stomach, intestine, rectum, and anus. The intestines diagram looks like a tubular structure that extends from the lower end of the stomach to the anus. The length of the intestine could be about 20 feet. Due to the size, length and function the intestine can be divided into two types, the large intestine, and the small intestine. Let us look at each type in detail, length of small intestine and large intestine, their functions, sub-divisions, and many interesting facts.

Large Intestine:

A type of intestine whose diameter is wider than that of the other is considered to be a large intestine. The large intestine length is about five feet. It takes a much straighter path in the abdomen. By the time food has reached the large intestine the food has been mixed with the digestive system. And most of the digestion and absorption has taken place. 

What is left without getting absorbed is a fibre that takes more time to digest, bile pigments, dead cells from the lining of the intestine. This mixture is the food for the bacteria that is present in the large intestine. Later this bacteria produces helpful vitamins and minerals that get absorbed in the blood. 

Large Intestine Anatomy:

The large intestine can be further divided into three parts:

1) Cecum: The first section of the large intestine looks like a pouch and is about two inches long. This pouch is called a cecum. The digested liquid from the ileum is passed on to the colon, through the cecum.

2) Colon: The major section of the large intestine is the colon. It is the principal section for the absorption of the salts and reabsorption of the water. It can further be divided into four different parts,

Ascending Colon: It is connected to the small intestine through the cecum. It is approximately eight inches in length. It runs through the abdominal cavity towards the transverse colon. The main function of the colon is to remove the waste materials by absorbing the required nutrients. The waste is been pushed towards the transverse colon by the process of peristalsis. 

Transverse Colon: It is also called right colic from the hepatic flexure. And left colic from the splenic flexure. The food is moved to the second portion of the colon. It is present just across the abdominal wall.

Descending Colon: It is the third portion of the colon, where the food is pushed to the next stage near to lower left stage of the abdomen. It is just near the spleen. The faecal matter that has to be eliminated is stored here.

Sigmoid Colon: The ‘S’ shaped portion of the colon is considered a sigmoid colon. It is muscular in nature and contracts to increase the pressure inside the rectum. 

Rectum: It is the last section of the large intestine. The waste is collected in the rectum. The waste can be removed by the process of defecation.

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Small Intestine:

The small intestine is also called the small bowel. It is a long tube-like structure. The length of small intestine is about 15 feet long. It runs from the end of the stomach and connects to the large intestine. The breakdown of the food takes place in the small intestine where most of the food is absorbed. Before the food has reached the small intestine it has converted to form a liquid, by breaking down the large particles and mashing. About two to three gallons of liquid is transferred to the small intestine every day. Most of the digestion process is carried out here by absorbing the nutrients. These nutrients get into the bloodstream. The digestive enzymes or juices are formed in the small intestine that works with enzymes from the liver and pancreas.

It consists of segments,

1) Duodenum: It takes the semi-digested food from the stomach via pylorus. The remaining digestion process starts from here. It also takes bile juice from the liver, gallbladder, and pancreas.

2) Jejunum: It is the middle part of the small intestine. The food is carried rapidly to the ileum by wave-like muscle contractions. 

3) Ileum: It is the longest and the last part of the small intestine. Most of the nutrients have been absorbed here. Later the food is emptied into the large intestine.

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Small Intestine Function:

Sometimes it is hard to believe that the narrower, pipe-like structure can do such a big job. The absorptive area of the small intestine could be about 250 square meters which are equal to the surface area of the tennis court. Well! There are three features of the small intestine that can allow it to have such a huge absorptive area packed in a small space.

1) Mucosal folds: The inner surface of the intestine is not found to be flat instead it has circular folds. This feature helps it to have a larger surface area. Along with this, the flow of the food is also regulated.

2) Villi: The circular folds have numerous tiny projections that stick into the open space of the small intestines. It has cells that help to absorb the nutrients from the food that passes through it.

3) Microvilli: Cells of villi are packed with tiny hair-like projections called microvilli. They help to increase the surface area of each of the cells in villi. Thereby increasing the amount of absorption of the nutrients.


The digestive system aims at converting food into small molecules such as amino acids, glucose and fatty acids. The broken food further gets absorbed into the bloodstream in the small intestine. Thereby transporting the nutrients to each and every cell of the body.

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FAQs on Human Intestine

1. What is the intestine? What is the length of the human intestines?

The intestine meaning is as follows, it is a long, tube-like structure that starts from the stomach to the anus. It is where the absorption of the water and nutrients takes place. The combined length of the intestine is approximately 20 feet. 

2. Mention the large intestine functions?

There major functions of the large intestine:

  • Recovering the water and electrolytes from the food.

  • Formation and storage of the faces.

  • Some of the indigestible food is fermented by the bacteria present in the intestine.