Kaplan Nursing Entrance Practice Exam

Where does chemical digestion begin?

1. Stomach

2. Small intestine

3. Mouth

4. Esophagus

The correct answer is: Mouth

Chemical digestion starts in the mouth, where enzymes in saliva begin to break down food. Saliva contains amylase, an enzyme that specifically targets carbohydrates. As food is chewed and mixed with saliva, this enzymatic action initiates the process of breaking complex carbohydrates into simpler sugars, which not only aids in digestion but also enhances the process of taste as food is prepared for swallowing. While other parts of the digestive system also play crucial roles in digestion, they specialize in different processes. For instance, in the stomach, gastric juices facilitate the digestion of proteins but do not initiate the chemical breakdown of carbohydrates. The small intestine is primarily where most digestion and nutrient absorption occur but relies on digestive juices from the pancreas and bile from the liver. The esophagus functions mainly as a passageway for food to travel from the mouth to the stomach and does not participate in chemical digestion. Thus, it is in the mouth where the significant chemical digestion is set in motion.