Mechanical Digestion: The Initial Breakdown of Digestion

As soon as you eat, the digestive process of breaking down food particles begins. The first digestive process, mechanical digestion, involves the actions of the teeth and tongue to break food particles into smaller pieces. Later the smaller pieces of food will be further broken down by enzymes during chemical digestion. In this activity you will see how mechanical digestion aids chemical digestion.

Materials

Two paper cups, each filled with 100 ml water

Two sugar cubes of equal size

Spoon

Paper towel

Watch with a second hand

Small plastic bag

Activity

1. Place one sugar cube in a plastic bag and use your textbook and hand to crush it until only sugar particles remain.
2. Simultaneously, drop a whole sugar cube into one cup of water while pouring sugar particles from the baggie into the other cup of water.
3. Wait thirty seconds. Examine the contents of the cups by swirling gently. In which cup was the sugar more effectively dissolved?

Follow-Up Questions

1. Which part of the digestive process do you think crushing the sugar cube represented in this activity?
2. In which cup was more of the sugar dissolved?
3. How does this demonstration represent what happens to food particles in the body after you ingest them?

Answers

1. Mechanical digestion due to the action of the teeth and tongue.
2. More sugar will be dissolved in the cup of water with crushed sugar.
3. Before food is swallowed, the teeth and tongue begin the process of mechanical digestion.

Extension

Some medications are taken as powders, while others are taken as pills. Why do you think this is so?