Mechanical digestion is the physically breaking into smaller pieces by chewing in the mouth or churning in the stomach

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Digestive System

Digestion is the process by which food and drink are broken down into its smallest parts, so the body can use it to build new cells, nourish the body, and provide energy. Digestion begins in the mouth when food is chewed and is completed in the small intestine. The chemical process varies for different kinds of food.


Digestion has three components: mechanical digestion, chemical digestion, and absorption.

  • Mechanical digestion is the physically breaking into smaller pieces by chewing in the mouth or churning in the stomach.

  • Chemical digestion is caused by digestive juices such as stomach acid, and enzymes produced by glands.

  • Absorption occurs in the small intestine for food, and the large intestine for water, for distribution to the rest of the body. Reinforce that absorption is a physical change that occurs in digestion.


Journal of a Hamburger

Draw the chart in your notebooks, leaving a larger enough space for your responses than is indicated on the handout.



Return to the data collected during the Modeling Digestion Lab. Ask for student volunteers to read their hypotheses aloud. Write several responses on the board.

Develop a common hypothesis from the samples given within your groups.  

A hypothesis is a tentative statement that proposes a possible explanation to some phenomenon or event. A useful hypothesis is a testable statement which may include a prediction. A hypothesis should not be confused with a theory. Theories are generalizations based on a large amount of data.


Answer the following questions.

  • What did the plastic bag represent in this model?

  • What did the petroleum jelly represent in this model?

  • What did the vinegar represent in this model?)

  • Which type of food digested the quickest in this model?

  • What are some limitations of this model? Explain.


Write a conclusion that either confirms or disproves the hypothesis for the activity. You may use your observations and the information on the Journal of a Hamburger chart.


Answer the following questions

  • What organs allow the digestive system to function?

  • What is the function of the digestive system?

  • What body systems work together to help the digestive system?

anus - the opening at the end of the digestive system from which feces exit the body.
appendix - a small sac located near the start of the large intestine.
esophagus - the long tube between the mouth and the stomach. It uses rhythmic muscle movements (called peristalsis) to force food from the throat into the stomach.
gall bladder - a small, sac-like organ located by the duodenum. It stores and releases bile (a digestive chemical which is produced in the liver) into the small intestine.
large intestine - the long, wide tube that food goes through after it goes theough the small intestine.
liver - a large organ located above and in front of the stomach. It filters toxins from the blood, and makes bile (which breaks down fats) and some blood proteins.
mouth - the first part of the digestive system, where food enters the body. Chewing and salivary enzymes in the mouth are the beginning of the digestive process (breaking down the food).
pancreas - an enzyme-producing gland located below the stomach and above the intestines. Enzymes from the pancreas help in the digestion of carbohydrates, fats and proteins in the small intestine.
rectum - the lower part of the large intestine, where feces are stored before they are excreted from the body.
small intestine - the long, thin winding tube that food goes through after it leaves the stomach.
stomach - a sack-like, muscular organ that is attached to the esophagus. When food enters the stomach, it is churned in an acid bath.


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