Friday, November 4, 2011

Human Body - Digestive System Simulation AKA Making Poop

This week at our co-op, our middle school anatomy class did a great project simulating the digestive system. It was so gross! Here's what we used:

- a hot dog w/ a bun
- a banana
- creamed corn
- instant oatmeal
- lemon juice
- green bean baby food
- food chopper
- paper plates
- plastic spoon
- 1" clear tubing (looked like clear PVC) about 15" long
- quart size freezer bag
- gallon size freezer bag (to place the quart sized bag inside in case of mess)
- cup
- pantyhose
- disposable roasting pan
- disposable cake decorating bag
- 2 syringes (like you give medicine to babies with OR bulb syringes)
- a sharp knife or scissors (to cut pantyhose)
- water

We made a meal of a hotdog w/ a bun, banana, and creamed corn (a couple bites worth of each) on our paper plate (doubled up). We chopped it with the food chopper and smashed it with the bottom of our cup (to simulate both incisor and molar action on the food). We added instant oatmeal for a thicker consistency and squirted some water (saliva) on it with a syringe. Then we scooped it with the spoon into our clear tubing that was inserted into a quart sized ziploc bag with lemon juice in it (esophagus and stomach). As our "bites" traveled down our "esophagus" we discussed peristalsis and that in a real esophagus the food doesn't just fall to our stomach, but is squeezed there by the muscular action of the esophagus.When the food reached the "stomach," the quart bag was zipped up and squeezed to simulate the churning action of the stomach along with the chemical action of the stomach acid (lemon juice). If it was too liquid at this point, we added some more instant oatmeal to thicken it up. Then, we emptied the "stomach" into our "duodenum" (cup) and squirted in some "bile" (green baby food w/ syringe) and "pancreatic juices" (more water with other syringe). We mixed it up and discussed that our body is now absorbing the nutrients from our food, the bile is helping break down fats into usable particles and the pancreatic juices are helping to break down the carbs. At this point, we poured our meal into the "large intestine" (one leg of the pantyhose with the roasting pan underneath) where we applied more "peristalsis" (squeezed the glob to allow the liquid to be "absorbed" and to move the blob down the leg of the pantyhose), eventually resulting in a rather firm blob at the end of the pantyhose. Then, we cut off the end of the pantyhose and dumped our blob into our "rectum" (cake decorating bag) where it was squeezed down and expelled into our "toilet" (roasting pan).

We did this entire simulation, discussing it the whole way. Then we reviewed what we did and decided it was so much fun, we did it all over again. There was a lot of smelling, jokes and offers to eat the poo (which I strongly discouraged), but it was a memorable lesson and the kids can thoroughly explain the digestive system now, which was the whole point. One student, a girl, actually told her mother afterwards, "I got to be the rectum!" Don't get that every day.

If you decide to do this with your students, I recommend adding brownies to the meal. The kids were disturbed that the color wasn't quite right, but were otherwise very impressed.

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