mouth

Cavity forming the entrance to the digestive tract (gut or alimentary canal). In land vertebrates, air from the nostrils enters the mouth cavity to pass down the trachea. The mouth in mammals is enclosed by the jaws, cheeks, and palate. It contains teeth that may have a variety of functions depending on the way of life of the mammal. They may be used to hold things, to kill other organisms, or to cut food.

Teeth are usually also involved in digestion in that they cut or crush large pieces of food into smaller pieces and mix them with saliva. Saliva is a digestive juice which contains the enzyme amylase. This enzyme breaks down the large insoluble molecules of starch into smaller soluble molecules of complex sugar. These sugar molecules are broken into the simpler sugar glucose later in the alimentary canal.

Starch is rarely in the mouth long enough to be digested completely. However, in the small intestine the pancreas produces a digestive juice that also contains amylase, so it is here that starch digestion is completed.