The BIG MAC is placed in the mouth. The bread is mainly starch, the special sauce is mainly fat, lettuce, pickles, and onions are niacin. The beef patties are protein,and cheeseis a form of calcium, fat, and protein. The piece of the BIG MAC is placed in the mouth and chewed, the starch is being digested by saliva. The starch becomes a kind of sugar which is used as a nourishment for the cells. Saliva changes food to a form that can be used by the body called enzymes. The burger is swallowed and passes into the esophagus. This is the muscular tube that contracts along its length to push the food down into the stomach. In the alimentary canal the meat and special sauce is being absorbed. The fat in the sauce is used for energy and the protein in the meat is used to build muscles, the lettuce, pickles, onions are also absorbed. In the stomach, which is a muscle, the food is churned about while digestive juices pour int from glands in the stomach wall. Eventually, the the churning action moves food out of the stomach and into the small intestine. The lever contributes to this digestive process by secreting into the small intestine, a liquid called bile. The pancreas secretes pancreatic juice which further aids in dissolving food.
The small intestine undergoes continual muscular contractions called peristalses. This action pushes food into the large intestine. This surface of the small intestine has a large number of threadlike projections called villi. The digested, liquified food is absorbed through the villi, and passes into capillaries that are inside the villi. Now the food is in the bloodstream. Not all parts of the BIG MAC can be digested.Those parts which are indigestible pass through the large intestine to its lower part, called the rectum. Eventually, the indigestible food is eliminated from the rectum through the anus. This is the complete teck that the BIG MAC follows when it is eaten.