The digestive tract is highly compartmentalized. Describe the compartments and why it is important to separate different processes.
In general, there are six stages of a digestive tract. First, food is ingested and taken into the organism from the outside environment. Second, muscular contraction propels food through an alimentary canal. Third, food is broken down by physically crushing it into smaller pieces through mechanical digestion (this can actually take place at several locations throughout the system). Fourth, chemical digestion takes place and enzymes break down the food molecularly. Fifth, the product of this digestion is absorbed into the cells of the organism. Sixth, indigestible substances are eliminated through defecation.
The digestive tract is compartmentalized so that organs can specialize in carrying out these stages. The stomach specializes in chemical digestion because it is lined with mucus that protects its cells from the enzymes. If the cells were exposed to the enzymes, they would be broken down and digested along with the food particles. The small intestine specializes in absorption by having a high surface area. More nutrients can diffuse through the cell membranes when there is a higher surface area exposed.