When you look at your body you probably do not notice what a stupendous factory and laboratory it is. In fact, breathing is an astounding chemical event by itself. Oxygen, inhaled from the air, is used in the burning process of the body, and exhaled out of the body as carbon dioxide.
As for digestion, it functions like a factory. After the food and drink taken through the mouth are decomposed and digested in the stomach and bowels, the parts useful to the body are percolated in the small intestines and transfused into the blood, while the dregs are excreted through the bowels. This extraordinary process is done automatically with the utmost precision, resulting in the body working like a factory.