Rabu, Mei 20, 2009

The Digestive System


When you are hungry and you smell dinner, your mouth waters. This is the first step in changing the food you eat into the kind of food that cells can use. This change is called digestion and it begin in the mouth.

Suppose you are eating sandwich. Your front teeth cut and tear the sandwich. The molars grind it, salvia, the juice in the mouth, gets everything moist.

Salvia also contains a type of chemical called an enzyme. It starts breaking down the starch of the bread into sugar.

The moist ball of the food is carried to the back of the mouth by the tongue. Muscles force the food into to esophagus, behind the windpipe. Other muscle force the food to esophagus. They do their work so well that the food would travel along even if the person were doing a headstand.

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