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www.GOALias.blogspot.comand the chest. Food is pushed down bymovement of the wall of the foodpipe.Actually this movement takes placethroughout the alimentary canal andpushes the food downwards (Fig. 2.7).At times the food is not accepted by ourstomach and is vomited out. Recall theinstances when you vomited after eatingand think of the reason for it. Discusswith your parents and teacher.The stomachThe stomach is a thick-walled bag. Itsshape is like a flattened U and it is thewidest part of the alimentary canal. Itreceives food from the food pipe at oneend and opens into the small intestineat the other.The inner lining of the stomachsecretes mucous, hydrochloric acid anddigestive juices. The mucous protectsthe lining of the stomach. The acid killsmany bacteria that enter along with thefood and makes the medium in thestomach acidic. The digestive juicesbreak down the proteins into simplersubstances.The small intestineThe small intestine is highly coiled andis about 7.5 metres long. It receivessecretions from the liver and thepancreas. Besides, its wall also secretesjuices.The liver is a reddish brown glandsituated in the upper part of theabdomen on the right side. It is thelargest gland in the body. It secretes bilejuice that is stored in a sac called thegall bladder (Fig. 2.2). The bile playsan important role in the digestion of fats.The pancreas is a large creamcoloured gland located just below thestomach (Fig. 2.2). The pancreatic juiceacts on carbohydrates and proteins andchanges them into simpler forms. TheThe working of the stomach was discovered by astrange accident. In 1822, a man named Alexis St.Martin was badly hit by a shot gun. The bullet hadseriously damaged the chest wall and made a holein his stomach. He was brought to an Americanarmy doctor William Beaumont. The doctor savedthe patient but he could not close the hole properly(Fig. 2.8). Beaumont took it as a great opportunityto see the inside of the stomach through the hole.He made some wonderful observations.Beaumont found that the stomach was churningFig. 2.8 Alexis St. Martin’sfood. Its wall secreted a fluid which could digestshotgun woundthe food. He also observed that the end of thestomach opens into the intestine only after the digestion of the food inside thestomach is completed.16SCIENCE