The 7 parts of the intestine: characteristics and functions

The digestive tract consists of a collection of organs responsible for the process of digestion, or what is the same, for transforming food by hydrolysis into molecules small enough to cross the cell plasma membrane. Through the digestive tract, exogenous nutrients reach the cells, which use them for respiration and many other metabolic processes.

The digestive system has several functions, including the following: transporting food throughout the body, secreting acids, absorbing nutrients, and excreting non-metabolizable wastes. Without a doubt, understanding human life as it is without this system would be utterly impossible.

When we think of the digestive tract, we usually automatically think of the stomach, where the bolus is mixed with many digestive juices. Beyond this very interesting structure, another equally essential section is generally more covered: the intestine.

In this article we will see what are the parts of the intestine and how they work in the process of digestion and evacuation.

    What are the most important parts of the intestine?

    The intestine is the part of the digestive tract located between the stomach and the anus. It is a long, tube-like organ (located in the abdomen) in which the digestion process is completed, Because here most of the nutrients and water ingested during the feeding process are absorbed.

    By adding all the parts that make it up, the intestine reaches up to about 7.5 meters in length. These data have a great biological and evolutionary significance, because the greater the total surface of the tissues, the more the absorption of nutrients and water can proceed until the inevitable excretion of food. In addition, to further increase the absorption surface, the intestinal mucosa presents small projections, called intestinal villi.

    Before continuing, it should be clarified that the intestine is divided into 2 portions: the thinner and the thicker. We explore their peculiarities separately because, although part of the same general structure, they perform different functions and have different anatomy. Let’s do this.

    The small intestine

    The small intestine can be defined as a small, tube-like organ that connects the stomach with the large intestine. It measures about 6 meters, which is why it must have several folds and folds to be located in the abdomen of the human being.

    Its most important function is the absorption of nutrientsTherefore, it has specialized structures and further increases the available surface area without compromising the viability of the organ. Some of them are:

    • Circular folds: transverse folds about 8 millimeters high and 5 centimeters long that show the mucous membranes of the small intestine. They increase the absorption surface by 3.
    • Intestinal villi: finger-shaped structures that cover the small intestine and give it a velvety appearance.
    • Microvilli: extensions of the plasma membrane of enterocytes, cells of the intestinal epithelium. They increase the absorption area.

    The small intestine absorbs hundreds of grams of carbohydrate daily, around 50 to 100 grams of amino acids (essential for protein formation) and up to 7 liters of water. After exploring its general physiology and functionality, we can briefly describe its parts.

    1. Duode

    It is the first part of the small intestine, located between the stomach and the middle part of the small intestine, also known as jejunum. Food is already partially broken down in the duodenum thanks to gastric acids, but here a substance essential for the absorption of nutrients is released: bile.

    Bile, secreted in the liver and stored in the gallbladder, is released into the duodenum after food is taken. It is composed of bile salts with emulsion characteristics of fats, proteins, cholesterol and water (the latter corresponds to 97% of the total). Thus, the absorption of vitamins, minerals and other nutrients begins in this part of the small intestine.

    2. Yeyuno

    This term refers to the part between the duodenum and the ileum. Its function is the absorption of substances from the food chyme, which has already been attacked by bile salts. Fasting has a lot of circular folds and intestinal villi, to maximize the absorption surface. Thanks to them, in a small portion of fabric a not insignificant amount of absorbent work is carried out.

    3. Ileó

    Jeju and ileum are a bit difficult to distinguish with the naked eye, as there is no exact separation between the two. In general, the ileum is “less”: it is 1 centimeter in diameter smaller, less circular folds and thinner hairs and walls.

    Ili performs absorption, secretion and motility functions, although to a lesser extent than jeju. Yet it is of essential importance: here vitamin B12 and most of the bile salts are absorbed.

      large intestine

      The large intestine is defined as a long, tube-like organ that connects to the small intestine on one end and to the anus on the other. It is shorter in length than the small intestine, but it is still huge if we consider its location: we are talking about 1-1.5 meters.

      Unlike the small intestine, food bolus processing is no longer done here (at this point known as kilograms). The large intestine is limited to absorbing minerals, water and vitamins. Then I discuss your parts.

      1. Conduct of the blind

      This is the “pocket” that forms the first part of the large intestine, connecting the small intestine to the colon. The function of the blind is very curious, because it contains symbiotic bacteria capable of degrading substances impossible for humans to assimilate, such as cellulose. These compounds of plant origin can represent up to 10% of the daily calorie intake.

      2. Colon

      It is the longest part of the large intestine, nearly 1.5 meters in length and 6.5 centimeters in diameter. This structure is responsible for extracting water, nutrients and electrolytes from partially digested foods, giving rise to feces.

      By the time the food mass reaches this point, almost all the nutrients and 90% of the water have already been absorbed. Therefore, its function is the final absorption and action of the intestinal flora, which gives the feces its unpleasant organoleptic characteristics.

      Unfortunately, the colon surely seems to you to be something more than its physiological characteristics. In terms of incidence, colorectal cancer is the third most common type of neoplasm, Just after the lung and breast. The average age of presentation is 70 to 71 years, although it can also be presented in younger people.

      3. Right

      It is the last section of the digestive tract, located immediately after the sigmoid section of the colon. It has a length of about 15 centimeters, and is the place of reception of waste which remain after digestion, i.e. the feces itself.

      It is one of the most important organs for understanding human defecation. The rectal vial is a site of fecal reception, and when its walls are dilated by the presence of organic matter, the nervous receptors in the vegetative system cause the urge to evacuate that we all know.

      4. Any

      It is a hole common to many animals through which the excretion of feces into the environment occurs, as it is here the sphincter that regulates the process of defecation. The anal canal runs from the rectum to the perianal skin and is covered with a mucous membrane covering the internal sphincter.

      The inner lining layer of the anus is divided into 3 sections: glandular, transitional and scaly. This structure measures approximately 4 centimeters and is made up of 4 muscle groups involved in the defecation.


      As you may have noticed, each part of the intestine has a specific function and plays a key role in the digestion process. From the movement of the bolus to the breakdown of substances, the intestine aims to absorb as much water, nutrients and useful products as possible before actual excretion takes place. fingers.

      If we want you to stay with a central idea of ​​this space, it is the following: the intestine (especially in its thin part) has multiple cellular and tissue structures specific to humans, in order to increase the surface area of ​​the human body. absorption as much as possible without compromising the functionality of the organs involved.

      bibliographical references

      • Colon cancer, SEOM. Collected January 3 from
      • Colon, NIH. Collected January 3 from
      • Duodè, Retrieved January 3, from
      • Intestine, NIH. Collected January 3 from
      • Small intestine, NIH. Collected January 3 from
      • Large intestine, NIH. Collected January 3 from

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