We began the digestive system with the mouth. The boys added the taste buds and the face to our skeletons. Then they made a large model of the mouth for their notebooks. These show where on the tongue are the taste buds that specialize in certain flavors. They then could match different foods with specific flavors to the appropiate areas on the tongue.
Using a straw, we demonstrated how the esophagus works. I made a ball of paper small enough to fit into a straw and yet not so small as to easily slip through. The boys used their fingers to squeeze the straw, pushing the ball of paper through the tube. We talked about how our esophagus muscles do the same thing to push our food to the stomach.
The small intestine was the next to be added to our body model.Steven and I had measured out a 21-foot piece of string in advance so that the boys could stretch it out to see for themselves how long the average adult small intestine is if uncoiled.
We discussed how food at this point is a pasty mixture called chyme and that it is the intestine's job to get the nutrients out of the chyme to our bloodstream. They then added a window in the small intestine to show the villi inside. We discussed how the villi increases the surface area of the intestine to insure rapid and thorough absorption.
We finished up the digestive system with the liver. The gallbladder in the liver produces bile that flows through a duct to the first part of the small intestine to break fats apart.
The pancreas (orange organ peeking out) produces enzyme rich juices that flow through a duct to further break down proteins, fats and carbohydrates in the small intestine. Parts of food that cannot be used by the body are moved along to the large intestine. Most of the water and minerals left are passed through the wall of the large intestine and into the blood. The rest solidify and are stored in the rectum until it is released from the anus, the opening at the end of the large intestine.
The models can be found in The Body Book by Donald Silver and Patricia Wynne.