Copyright © 2007 Dorling Kindersley
Food enters the body through the mouth. The mouth is the first part of the digestive system, where food is mashed and moistened, so that it can be swallowed. The mouth also plays an essential role in speech and breathing.
Saliva contains chemicals that kill bacteria, and it flows constantly into the mouth to help keep it free of disease. The mouth’s inner lining also secretes a lubricating fluid called mucus. Saliva and mucus both moisten food, making it easier to swallow.
The front teeth cut up food, and the tongue and cheek muscles push it between the back teeth, where it is ground by the lower jaw. Saliva softens and moistens food and washes over TASTE BUDS in the tongue so that flavors can be identified. The digestive process also begins in the mouth—saliva contains chemicals that break down some foods.
Our sense of taste comes from tiny, onion-shaped clusters of cells called taste buds. Most taste buds are scattered across the surface of the tongue, where there are around 10,000, but they are also found in the roof of the mouth and the throat.