The Digestive System
Rachel Milovich
Southwestern University
Background Information:
- We need food to stay alive, so that our body’s cells can stay alive and do their work.
- Our body has to change the food into a form cells can use. This process is called digestion and it takes place in the digestive system.
- Digestion starts in the mouth. Your teeth break the food into small pieces. Your tongue mixes the food with saliva. The saliva wets the food and begins to change it.
- Everyone has two set of teeth; baby teeth and adult teeth.
- The food then goes down your esophagus, as known as, your food tube. An adult esophagus is about 25 centimeters long. Muscles in the esophagus contract and relax to push the swallowed food down toward the stomach.
- The stomach is a baglike organ with muscular walls. The food mixes with the digestive juices that come from the walls of the stomach. Then the stomach squeezes the food into the small intestine.
- The small intestine is a curled-uptube. An adult’s small intestine is about 20 feet long. The food stays in the small intestine for about three to six hours. Juices made in the lining of the small intestine and nearby organs finish digesting most of the food. The food now looks like thin, watery soup.
- This thin liquid contains nutrients from the food you ate. The food has been changed to a form that your cells can use. The thin liquid goes into the capillaries that line the walls of the small intestine. From there the liquid passes into the blood and is carried to the body cells.
- Not all food can be digested. Skins and seeds from fruits and vegetables are not digested. This undigested food moves into the large intestine. The large intestine removes much of the liquid and stores the resulting solid waste until it leaves the body. This solid waste leaves the body after ten hours to a day or more. The waste is then moved out of the body through the rectum. This movement is called a bowel movement.
Grade Level and TEKS standard: 4th grade
§115.6. Health Education, Grade 4. (b) (2)Health information. The student recognizes the basic structures and functions of the human body and how they relate to personal health throughout the life span. The student is expected to:
(A)describe how health behaviors affect body systems; and
(B)describe the basic function of major body systems such as the circulatory and digestive systems.
Materials and Manipulatives:
-chart paper-panty hose
-markers-Ziplock bags
-bananas-yarn
-graham crackers-yard stick
-Dixie cups-saltine crackers
Procedures:
- Begin with discussion about what the students know about the digestive system. Record these statements on chart paper.
- Show students symbolic representations of the different organs in the digestive system, sharing facts about and measuring the length/time of each model.
- Today we are going to learn about the digestive system. (Have apron on)
- Point out the main parts of the digestive system, mouth, esophagus, stomach, small intestine, large intestine, and rectum.
- Review by having a large chart of the digestive system. The students will then be chosen to label the parts on the chart.
- We will then describe the function of each part of the digestive system.
- Review each function with activity.
- Hands on activity: Break up graham cracker into the bag (simulates chewing), place 1/2 banana into bag, place water into bag (simulates saliva), seal bag with not much air inside (or that will simulate gas), smash up food and water with your hands (simulating the churning of the stomach). Do that for about 5 minutes. Then, cut small hole in the corner of the bag so food can run out into the stocking. Squeeze the food from the bag into the stocking (over newspaper). Squeeze the food through the stocking (representing the small intestines and the water coming out of the stocking represents the nutrients going to the rest of the body.
Then, squeeze the food (waste) into the cup (representing the large intestine). Poke a hole in the cup and push food thru to represent the excess, unused food exiting the body. (Taken from - Colloquium: use chart to assess what the students have learned; ask questions like, “Tell me something new you learned”, “Why is the digestive system important?” Have the students talk about the outcomes of the activity. Use creative dramatics to extend activity.
- Closure: Have the students write a cracker’s passage through the digestive system.