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Difference between small intestine and large intestine

The intestine is a segment of the digestive tract that lies between the stomach and rectum. This structure’s main function is to absorb the various nutrients and water contained in food.

Its first part is the largest, known as the small intestine. The final part, which is macroscopically thicker and has a wall of different characteristics , for these reasons it is called the large intestine.

Small intestine

It is shaped like a tube, with a diameter of approximately 3 cm and a length of around 7 meters. It consists of three parts: duodenum, jejunum and ileum.

Duodenum. It is the initial portion of the intestinal tube, located in continuation of the stomach, is 25 cm long and consists of four segments. Food reaches the duodenum after leaving the stomach through the pylorus, from there the ducts from the gallbladder and pancreas open and transport secretions known as digestive juices, which contain several enzymes needed to carry out the digestion of fats and sugars. 

Jejunum-ileum. It is located in continuation of the duodenum and in this segment it is arranged in a “U” shape, giving rise to the so-called intestinal loops. The jejunum-ileum is joined to the posterior abdominal wall through a membrane known as the mesentery. It is rich in structures called intestinal villi, which have the function of increasing the intestinal surface that comes into contact with digested food, which favors the nutrient absorption process .

Large intestine

It corresponds to the last part of the intestine, reaching 1.5 meters in length with a diameter of 7 to 8 cm. It has four parts: cecum, colon, sigmoid and rectum. 

Blind. It is the first part, it is located in the lower right region of the abdomen, where the orifice of which the appendix ends is located.

Colon. It is the largest portion of the large intestine and is divided into three parts, identifying the ascending colon located on the right side of the abdomen, the transverse colon located on the front of the stomach, and the descending colon located on the left side of the abdomen.

Sigmoid. It corresponds to a free wing-shaped fragment located in the lower left part of the abdomen and in continuation to the rectum.

Straight. It is the final part, has a larger diameter and constitutes a reservoir through which fecal feces accumulate until they are expelled to the outside through the anus.

This intestinal segment’s main function is to absorb the water that remains as food remnants after the various nutrients from the jejunum-ileum are absorbed.

The final waste contained within the colon and sigmoid is converted to fecal waste, excrement that must be evacuated to the outside. 

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