Project

Section 1 Summary

The digestive system ingest food, breaks it down and eliminates what can't be digest. Mechanical digestion is when food is chew and broken down to smaller pieces by using smooth muscles in the stomach and small intestine. Chemical digestion is when large amount of foods are broken down by enzymes that can be absorbed by the body's cell. Enzymes are proteins that speed up reactions. Amylase is an enzymes found in saliva that begins the process of chemical digestion by turning starches into sugars.

When the food leave the mouth, it goes to the esophagus. The food is pushed into the upper part of the esophagus by the tongue.A muscular tube that connects the throat to the stomach is the esophagus. Peristalsis is the process by which the wall of the esophagus, lined with smooth muscle, contract rhythmically to move food through the digestive system. The small plate of cartilage called the epiglottis covers the trachea when a person swallows. If the trachea is not open a person can choke and the food can enter the lungs.

Food passes through a circular muscle called a sphincter and into the stomach when food leaves the esophagus. Between the esophagus and stomach, The sphincter is called the cardiac sphincter. The wall of the stomach are composed of three overlapping layers of smooth muscle that are involved with mechanical digestion. They break down the food and mix it with the secretions of glands that line the inner wall of the stomach.

The food then passes through the small intestine that is about 7m in length. It is the longest digestive tract. Its diameter is 2.5cm, which much smaller than the large intestine, that why it called small intestine. In the wall of the small intestine, the smooth muscles continue the process of mechanical digestion and push the food through the digestive tract.

The end portion of the digestive tract is the large intestine. It is about 1.5m long. It also include the colon, the rectum, and a small saclike...