Question

There's an old saying in Biology: "Form follows function." Describe how the structure of the small intestine supports how it functions.

Answer 1

In humans small intestine is divided into 3 parts: Duodenum. Jejunum and Ileum. The main task of the small intestine is the digestion and finally the absorption of the digested material into the blood or lymphatic system. As you know duodenum being the upper part close to stomach where digestion of food is completed with the help of digestive enzymes that are secreted by the duodenum itself, pancreas and gall bladder. therefore this part of small intestine lies in the vicinity of these organs and recieve the secretions. Moreover duodenum is not coiled like other two parts as it is chielfy concerned with the digestion of food along with emulsification of fats. Jejunum and Ileum are coiled tubes with thin lining enriched with villi and microvilli so as to increase the surface area of the organ so that maximum nutrients or digested material can be effectively absorbed. here it is to be noted that there is also access to lymphatic system for the absorption of large fatty acid molecules. Majority of the absorption occurs in the jejunum. In Ileum, mainly vitamin B12 and bile acids along with leftover digested food are absorbed. It is then connected to large intestines for the elimination of the undigested food materials out of the body. therefore the tubular structure of intestines along with the required anatomical features support the function it performs in human body.