As you can see, the digestion of a sandwich starts with the mouth.
Mouth
- The initial use of your teeth for biting and chewing breaks food up into smaller particles this is called mastication. Mastication happens so that you don’t choke on your food.
- Salivary glands located under your tongue and in the back of your mouth, secrete (this means that a substance is released from cells in response to a stimuli) saliva, which has a salivary amylase (an enzyme in saliva) that breaks down starches into simple sugars.
- Salivary amylase begins to break down starch into simpler sugars; in the mouth, this enzyme is the start of chemical digestion called hydrolysis. Bicarbonate ions in saliva help maintain the pH of the saliva almost neautral; between 6.5 and 7.5.
- A simple sugar is a carbohydrate molecule with 3 to 7 carbon atoms and the corresponding number of hydrogen and oxygen atoms. A polysaccharide is a complex carbohydrate that consists of many linked simple sugars.
- More saliva is produced to begin the process of breaking down food into a form your body can absorb and use. In addition, "juices" are produced that will help to further break down food.
- Your tongue is used to push the food to the back of your mouth. It rolls the food into a smooth lump called a bolus so you can swallow your food.
- The swallowed bits of food, or the bolus, enter the esophagus. The esophagus directs food from the mouth to the stomach.