During the process of digestion, these nutrients must be broken down into smaller parts for proper absorption. There are digestive enzymes which assist in this process. Enzymes are molecules which make biological reactions occur more efficiently. Consequently, digestive enzymes help break nutrients down, making digestion more efficient. The digestive process begins when food is placed in the mouth.
Chewing reduces the size of food particles and the saliva moistens food.
This release of sugar alters the taste of food. When the food is swallowed, muscle action propels the food downward to the stomach. The stomach fluids are quite acidic in nature and this acidity is beneficial to destroy ingested bacteria, activate some enzymes, and begin the process of protein digestion. Acid can damage the stomach, so the walls of the stomach have a special lining to protect it. Increases in stomach acidity can damage the protective lining and lead to a peptic ulcer.