Final answer:
The pharynx and esophagus do not secrete any digestive enzymes; enzymes like salivary amylase and lipase from the mouth continue to act on food during its passage through these structures.
Step-by-step explanation:
Digestive Enzymes in the Pharynx and Esophagus
The pharynx and esophagus are parts of the digestive system that primarily serve as passageways for food to move from the mouth to the stomach. No digestive enzymes are secreted in the pharynx or the esophagus; however, enzymes such as salivary amylase and lipase that originate from the mouth are still active until they reach the stomach. Salivary amylase begins the chemical digestion of carbohydrates, converting starches into maltose, while lipase starts the process of fat digestion. These enzymes are mixed with the food in the mouth and continue to act on food as it passes through the pharynx and esophagus. The esophageal walls secrete mucus to aid the passage of the food bolus but do not contribute additional enzymes for digestion at this stage.