Food digestion in the mouth is a combination of mechanical and chemical processes that prepare food for further breakdown in the digestive system.
Mechanical Digestion: Mastication
The initial step in digestion within the mouth is mastication, more commonly known as chewing.
- Teeth: The teeth mechanically break down food into smaller particles, increasing the surface area available for enzymatic action. This process reduces the size of food boluses making them easier to swallow.
- Tongue: The tongue manipulates the food, mixing it with saliva and forming a bolus that can be swallowed.
Chemical Digestion: Enzymes in Saliva
While mechanical digestion is crucial, chemical digestion begins in the mouth with the aid of saliva, which contains key enzymes:
- Salivary Amylase (Ptyalin): This enzyme begins the breakdown of carbohydrates (starches) into smaller sugars, like maltose.
- Lingual Lipase: This enzyme, although produced in the mouth, becomes most active in the stomach. It starts the digestion of fats, particularly triglycerides, into diglycerides and fatty acids. Lingual lipase is especially important in infants for digesting milk fats.
Summary of Digestion in the Mouth
| Process | Description | Enzymes Involved |
|---|---|---|
| Mechanical | Chewing breaks down food into smaller particles. | None |
| Chemical | Saliva starts the breakdown of carbohydrates and some fats. | Amylase, Lipase |
| Bolus Formation | Tongue mixes chewed food with saliva, forming a bolus for swallowing. | None |
In short, the mouth initiates digestion through chewing, which increases surface area, and through enzymes in saliva that begin the chemical breakdown of carbohydrates and fats. The chewed and partially digested food, now formed into a bolus, is then ready to be swallowed and continue its journey through the digestive tract.
