The function of the small intestine in the human digestive system

The small intestine

Small intestine

The small intestine .

The functions of the small intestine are completing the digestion of the different types of the food and the absorption of the digested food , The small intestine is composed of three structural parts which are the duodenum , the  jejunum and the ileum .

Everyone should know that the process of transferring the digested food from the small intestine to the blood is the absorption process . The small intestine follows the stomach and it is followed by the large intestine , The length of the small intestine is about seven metres , so , it coils inside the abdominal cavity  .

The digestive system

The human digestive system .

The duodenum

The duodenum is the first part of the small intestine that is connected to the stomach , There are two important juices pouring in the duodenum which are the pancreatic juice that is secreted by the pancreas and the bile juice that is secreted by the liver which helps the digestion of the fats where it changes the fats into the fatty emulsion .

The jejunum

The jejunum  connects the duodenum to the ileum , and it is the midsection of the small intestine , The length of the jejunum is about 2.5 m , It contains the plicae  circulares , and the villi that increase its surface area .

The products of digestion ( sugars , amino acids and fatty acids ) are absorbed into the blood stream here .

The ileum

The ileum is the part  of the small intestine that follows the duodenum , and in the ileum the intestinal juice is poured , The complete digestion of the different types of the food occurs in the ileum , The digestion of the fats occurs in the small intestine especially in the duodenum .

The food undergoes two processes which are the digestion and the absorption in the digestive system , and the digested food is absorbed by the small intestine walls , then it reaches the blood which distributes it all over the body organs .


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