One of the most important organs in our digestive system is the small intestine. The small intestine sits between the stomach and the large intestine and is by far the longest part of the digestive tract. In fact, it is estimated that it measures between 3 and 7 meters in length, influencing very varied factors such as the height and size of the person himself.

Likewise, it is also important to bear in mind that the small intestine is an organ that fulfills a fundamental function within the digestive tract, since it is in charge of absorbing most of the nutrients that we ingest. If you want to know a little more about the parts and functions of the small intestine, keep reading and we will tell you in detail.

Parts of the small intestine

The small intestine is located between the stomach and the large intestine and is divided into three well-defined parts:

  • Duodenum: The duodenum is the first part of the small intestine. It is just below the stomach, which also makes it the part of the small intestine that is most closely related to this other organ. In fact, it is in the duodenum where both liver and pancreatic juices are secreted, essential in the digestion of food.
  • Jejunum: The jejunum is the part of the small intestine that follows the duodenum. This is characterized by already having the well-known shape of an irregular-looking tube that turns on itself. In the case of the jejunum, it is the irregular part of the small intestine that is in the upper half of the small intestine (with the exception of the duodenum). It is difficult to differentiate it from the ileum because there is no such tangible separation as in the case of the duodenum. Among the main differences, it should be noted that this part of the small intestine has a slightly larger diameter than that of the ileum, as well as a greater number of intestinal villi.
  • Ileum: The last part of the small intestine is the ileum, which corresponds to the lower half of the small intestine. The ileum is located below the jejunum and ends in the large intestine. It differs from the jejunum in that it has a somewhat smaller diameter and fewer intestinal villi.

Small intestine functions

The main function of the small intestine is to absorb most of the nutrients that reach our body through intake. This occurs after the food has been digested in both the mouth and the stomach. In addition, thanks to the liver and pancreatic juices that are secreted in the duodenum, the food reaches the small intestine in an almost completely liquid form, which facilitates the absorption of nutrients.

The absorption of nutrients is carried out by contact of these nutrients with the intestinal wall, which explains why it is such a long organ with so many folds. In fact, the internal surface of the small intestine is plagued by irregularities in the form of intestinal villi that, in addition to allowing the absorption of nutrients, also allow the surface area through which said absorption is carried out to be expanded, making this organ one of the most efficient of the human body.

Small intestine diseases

The small intestine, like any other organ in the body, can become sick and present discomfort and pain to patients who suffer from a problem related to it. Some of the most common diseases related to this organ are the following:

  • Vascular diseases: these are diseases that usually occur in the small intestine due to the high number of arteries and veins that surround this organ (necessary for nutrients to pass into the blood). These types of diseases usually manifest as hemorrhages that affect the intestinal area and that, depending on the case, can be more or less serious.
  • Celiac disease: it is a disease characterized by intolerance to gluten, a protein present in some cereals such as wheat, oats or barley. It is an autoimmune disease that, among different symptoms, causes atrophy of the intestinal villi, which leads to a worse absorption of ingested nutrients.
  • Crohn’s disease: This disease of the intestine manifests as irritation and inflammation of the intestinal walls. It usually manifests itself mainly in the area of ​​the small intestine corresponding to the ileum, as well as in part of its continuation in the large intestine.
  • Tumors: Tumors can occur in many organs in the body, including the small intestine. The presence of tumors does not necessarily imply that they are malignant tumors. However, it will be the doctors who will determine the nature of the tumors and the most appropriate treatment in each case.


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