It’s an anatomy cake of SCIENCE!!!!
Today I’ll share how we made our digestive system anatomy cake, took a blind taste challenge, and modeled the process of the digestive system! You can find the projects listed throughout this blog post (with a cake finale!), and links and resources at the end. But first, let’s take a look at how the digestive system works…
The digestive system plays an incredibly important role in the proper function of the human body. All of the functions of our organs, tissues, and cells, rely on the nutrients gained from digested food. Every animal on Earth has some way to digest and process the nutrients from food; indeed, a way to gain nourishment from food is often the first major development within an embryo!
The process of digestion begins with your olfactory system (that’s your sense of smell!) and your taste buds. The average person has around 10,000 taste buds on their tongues that sense sweet, sour, salty, bitter and umami (savory) tastes. Kids actually have more taste buds than adults, as these sensory cells stop being replaced as we get older. By the time we reach old age, we may only have 5,000 working taste buds left in our mouths!
Before we move on to the rest of the digestive system, try this out with your friends!
TAKE THE TASTE TEST CHALLENGE!
4 small glasses
1. Have your friend help you make your taste test concoctions. Each glass will have a different liquid in it. You’ll want to make samples of salt water, sugar water, cocoa water, and lemon juice and water.
2. Blindfold your friend! Make sure they can’t see ANYTHING.
3. Switch your glasses around several times. Then set all four up in front of your friend. Take one toothpick for each glass and set it down in front of them.
4. Ask your friend to stick out his/her tongue. Choosing at random, pick up a toothpick and dip it into your mixture. Gently slide it across your friend’s tongue. See if they can correctly guess which mixture it is! Using a fresh toothpick for each glass, go through all of the liquids and see if they can tell which one you’re using!
5. Switch places and try it for yourself!
Extras: We had a lot of fun dipping it several times into the lemon juice. Try to trick your friends too! Instead of testing each mixture one at a time, mix it up! Choose one mixture in between the other (e.g. lemon, sugar, lemon, lemon, salt, lemon, cocoa, sugar, cocoa, etc.).
Try it on different areas of the mouth! We’re all pretty familiar with the (now debunked) taste bud map of the tongue. Are our senses really so strictly divided? Try putting your toothpick of lemon juice where sweet should be, or your sugar where salty should be!
Moving along through the digestive process, our mouth does a lot more than just taste your food! When you take a bite of something (like a crunchy apple) your mouth produces saliva, a liquid containing enzymes that softens and dissolves your food. Your teeth mash together, chomping and breaking things down smaller pieces. Your tongue pushes the pieces of food together into a lump of chewed food called a bolus.
When you swallow the bolus, your esophagus muscles swing into action to start pushing your food down toward your stomach. Incredibly, this involuntary muscle action (called peristalsis) will still push your food down if you’re upside down, or even in space!
Once your food is pushed into your stomach, the real digestive action begins! Your stomach muscles churn the food about, while highly acidic compounds called gastric acids break apart the proteins and fats in your food. This acid is highly potent, in fact, if you were to get it on your skin, the hydrochloric acid would burn a hole right through it! This is why the stomach has a thick layer of mucus; it protects the lining of your stomach against these intense chemical agents.
After it’s acid bath, your lump of chewed up food has become a liquid soup of nutrients called chyme. A sphincter opens up from your stomach, allowing your muscles to push that chyme into your small intestine. While it is called the small intestine because of its diameter (just about 1 inch), this organ is actually quite large, ranging from 10 ft to 22 ft in length!
It is here where the vast majority of the nutrients are absorbed from your food! The liver sends bile to the small intestine, while your pancreas sends pancreatic juices to help in the breakdown and absorption process. Small hairlike cells called villi absorb vitamins, minerals, fats, sugars, and other necessary nutrients.
Once your food has traveled through your small intestine, it makes its way through the large intestine! The large intestine is only 5 feet in length, but has a diameter of about 2.5 inches. It is here where your chyme has its final stage of nutrient absorption, as your own personal colony of gut bacteria absorbs the remaining vitamins and minerals. Your large intestine will also absorb most of the water from the slop, leaving behind a semi-solid mass of waste material. From here, it will be stored in the rectum until it can be eliminated from your body as fecal waste (poop!).
Now that we’ve learned all about how the digestive system works, let’s get some science going in our kitchen! It’s time to make a make a model of our digestive system!
MODEL YOUR DIGESTIVE TRACT!
Sandwich bag/small ziplock bag
Nylons/dollar store pantyhose
Two small glasses
Small amount of an acid (vinegar, lemon juice, or orange juice)
Small amount of water
Soft food (we used a peanut butter and jelly sandwich – you could use crackers too!)
1. Cut one of the legs off the nylon/pantyhose. You’ll want an opening at the top and the bottom to be closed off. Set this aside for later use.
2. Take your peanut butter sandwich and break it up into tiny pieces. This will mimic the mouth’s chewing and chomping action of breaking your food down. Put the pieces into the sandwich bag and add your water. This will act as the saliva, further breaking down your food.
3. Add the acid into your bag, simulating the hydrochloric stomach acids that work to break down your food. Continue mashing your food, pretending that your hands are acting as stomach muscles!
4. Now you should have a soupy mess of liquid “chyme”. Take your nylon tube and hold it over your shallow pan. Pour your chyme into the nylon. Start squeezing the chyme through the nylon. You’ll see a ton of watery material drain out of the nylon. This would be the nutrient rich material that is absorbed through the small intestine!
5. Once you’ve squeezed the water out, cut open the end of the nylon. You’ll see a mess of solid material. Now you’re going to have your paper towels act as the large intestine, absorbing the rest of the moisture out of your food substance! If you want to get really detailed, you can roll it into a nice shape, and examine your handiwork. You should have a nice round pile of…
Pretty gross, huh? Well, that’s the process of our digestive system! Without all of that goopy, sloppy, mess of chyme moving through our stomach and intestines, our bodies wouldn’t be able to function as they do! Our brain, heart, muscles, tissues, indeed, EVERY SINGLE CELL in our body relies on the nutrition gained from the process of digestion in order to work properly.
Now, there is a much more palatable way of appreciating our digestive system. One of our favorite projects of all time, was when I surprised my daughter and niece with making our very own digestive system anatomy cake! It was really easy, and really fun!
HAVE YOUR CAKE AND DIGEST IT TOO!
Cake Mix (and the supplies for baking!)
Several types of frosting
Flat knife/icing spreader
Various types of candy!
Printed pictures of digestive organs (we used the stomach, liver, and gallbladder)
Saran wrap/plastic wrap
(Optional) Decorative icing tips and plastic icing bags
Note: This post contains affiliate links to products.
1. Take your kids to the dollar store and pick out a bunch of candy! Have them make a list before you go, detailing what kind of candy they might use for each organ. We ended up using the following candies: Small marshmallows cut in half for teeth, Large Marshmallows for the large intestine, sour gummy worms for the lips and small intestine, a marshmallow “peep” cut in half for the pancreas, and a marshmallow tube for the esophagus.
2. Bake your cake! We used a simple box cake. I let the kids bake the cake themselves, which gave an added bonus lesson of math and measurements in the kitchen!
3. While the cake is baking, print out some pictures of the organs you weren’t able to buy candies for. We couldn’t easily find candies shaped like a stomach, liver, or gall bladder, so we printed these out, making sure that they were sized to fit our cake.
4. Tape one of the organs onto your table and place your saran wrap/plastic wrap over it. Tape that down as well. Follow the directions for your cake decorating tips and bag, and choose a tip you’d like to use. Fill your bag with icing and trace the organ onto the plastic wrap! Once you have it all drawn out and filled in, carefully move the plastic wrap onto a plate. Put this plate in the freezer for approximately 15 minutes. Repeat the process for any other organs you need to draw on.
Alternatively, you could draw on the organs with toothpicks or wooden skewers. We haven’t tested that method, however. The icing bags and tips we bought from our grocery store were $5, so we just used those.
5. When your cake is done and you’ve let it cool, it’s time to frost it! This will put the foundation of icing on your cake so you can then lay the details of your digestive system.
6. Now let the kids make their model of the digestive system! What are they going to use for teeth? How should they place the esophagus? Where should they put everything so that it fits in its proper place? Let the kids exercise everything they’ve learned and build an anatomy cake of wonders!
7. Take your organs out of the freezer and lay them icing side down on your cake. Peel off the plastic wrap and you’re set!
8. Once they’ve finished building their digestive system, it’s time to label their anatomy cake! Have the kids make their own labels and tape them to toothpicks. Then have them stick the labels where they go.
Now you’re finished! Stand back and admire your kitchen anatomy skills, and take a lot of pictures! As soon as you announce that you’re finished, your kids are going to immediately want to devour that cake! Honestly, it’s a fantastic reward for all the work you’ve all done, and you can talk about digestion while you’re eating and digesting that cake!
NOTE: Want to make an anatomy model of the digestive system, but don’t want to load your kids up with a ton of sugar? Here is an adorable skeletal model made with veggies! Use this as inspiration and carve your organs out of vegetables!
We had a fantastic time learning about the digestive system! The science projects we did really added a lot to our learning experience and made it so that the kids were able to recall each function of the various organs, long after we were finished learning about them! Below are some of the resources that we found to be useful along our learning explorations.
FURTHER READING AND OTHER RESOURCES
Make Me Genius: How the Body Works: Digestion!
Crash Course Biology: The Digestive System
The Magic School Bus: For Lunch! (Full Episode)
TED-Ed: You Are Your Microbes
Here is a fantastic set of resources on the digestive system from Parents.com. It’s an entire set of free digestive system worksheets and activities!
Here is an unlabeled diagram of the human body. This is the same image that was used above in the blog post, but your kids get to fill it in!
Rhonda Alborn’s kitchen poo!
The Homeschool Room’s digestive model and peristalsis experiment!
Web Sites and Resources
Kids Health: Your Digestive System. Get a great run down on the digestive system and how it works, in a kid friendly format.
Inner Body: Digestive System. This is a fantastic anatomy site with fully detailed diagrams, and extensive information on what each part of the body does.
Other Body Systems
Finally, if you want to learn about the heart and cardiovascular system, check out our heart unit!
If you want to learn about the sense of smell and the olfactory system, then follow your nose and see where it goes!