Food and the Digestive System 10 10.9 The large intestine
The role of the large intestine is to absorb water from the remaining undigested food into the bloodstream and to store undigested waste until it is eliminated from the body by egestion.
Structure of the large intestine The large intestine is about 1.5 m long but is twice the diameter of the small intestine, which is why it is called the large intestine. It does not have villi. The appendix is a 10 cm long, closed-ended
tube at the beginning of the large intestine. It no longer has a major function in digestion in humans. Scientists have different theories about its role in our body. It may have been involved in digesting fibrous foods in our ancestors. Appendicitis is when the appendix becomes infected and it must be removed before it bursts.
Large intestine
Appendix Fig. 16 The appendix
Research this Research the different theories about the function of the appendix in humans.
Fig. 15 Undigested food passes from the small intestine into the large intestine.
Function of the large intestine Undigested food passes through the large intestine where water is absorbed into the bloodstream. Waste material is stored in the rectum until it is egested as faeces through the anus.
Fibre Fibre does not have any nutritional value but is a very important part of a healthy diet. It helps the movement of food through the digestive system. Fibre-rich foods like whole bran and vegetables swell in the intestines, making it easier for food to be pushed along by peristalsis. Fibre absorbs waste products from the large intestine and transports them out of the body during egestion.
