What really happens to those vegetables after you eat them?
The digestive system is what helps us use the food we eat. It starts even before you crunch food up with your teeth – even seeing and smelling food gets your mouth ready to digest your food! As food goes through our bodies, it changes form so that we can get all the healthy things we need from it!
In this activity, you will learn about how food changes form during digestion.
-Locate and identify the major organs of the digestive system
-Demonstrate knowledge about what happens to food during the digestion process
- The digestive system is a series of organs that processes all the food we eat. This system includes the salivary glands, mouth, esophagus, stomach, liver, gallbladder, pylorus, pancreas, small intestine, large intestine, and rectum.
- Digestion is all about breaking food down into smaller and smaller pieces so that we can use the nutrients – like vitamins and minerals – that are in food.
- Digestion starts in the mouth where the teeth and tongue work to chomp the food and make it small enough to be swallowed.
- The chewed food goes through the esophagus into the stomach, which makes gastric juices, which are very acidic and help break down all the food even further.
- The broken down food pieces then enter the small intestines to be broken down even further by digestive enzymes from the liver, pancreas and gallbladder so the body can get all the available nutrients.
- Most nutrients get absorbed from the small intestine into the blood where they travel to other parts of the body to be used for energy or to make other important things the body needs.
- For example, glucose is absorbed from the small intestine into the bloodstream.
- After that, the broken down food goes through the large intestine. One job of the large intestine is to remove water from undigested matter and form solid waste that can be excreted (feces).
- There are lots of bacteria in the large intestine and further down in the colon that eat some of the remaining food products in feces (and some of these bacteria have a digestive system of their own too!) Our own 10 trillion or so cells are outnumbered by 100s of trillions of single cell bacteria living in us that play an enormous role in our health.
- The rectum is where feces are stored until they leave the digestive system through the anus as a bowel movement.
- A well balanced diet gives you the vitamins, minerals and nutrients your body needs.
- We are not only feeding ourselves but also the ‘biome’ in our intestinal tracts. Everything goes by them first before it gets to us. Plant foods rich in fiber help to cultivate a healthy ‘biome’. If you have a few minutes to learn more about this, check out this video!
- Very few Americans get enough servings of fruits and vegetables. A Healthy Eating Plate suggests that we eat twice as many servings of these plant foods as servings of whole grains and healthy proteins.
- Food labels provide important information on exactly what is inside a food before we eat it. Whole plant foods don’t have labels but are naturally packaged with vitamins, minerals, nutrients, fiber and water.
- Food labels only give information for one serving size. Not every package only has one serving size! This information tells us how many calories are in a serving of food and how many servings are in a package.
- Calories are energy that fuel our body. If we eat too many calories without burning them as fuel, we can gain too much weight (This link describes it well! https://www.pbs.org/video/fit-kids-18-energy-balance/)
- An easy way to reduce calories during the day is to choose water or low fat, unflavored milk instead of soda or energy drinks and to snack on fresh fruits and veggies instead of chips or other processed baked snacks, whether sweet or salty.
- The digestive system is made up of lots of organs in our body and a lot of ‘buddies in our bellies’, single cell micro-organisms (teeny, tiny but very hard-working bacteria) which all work together to break down the foods we eat and get all the healthy things your body needs from it.
- Whenever you eat something, the food starts to be digested in your mouth where your teeth crush it up into small pieces.
- Then it travels down into your stomach, where there are lots of acidic juices and some bacteria waiting to help break the food down even more!
- After that, everything goes through the small intestine, where lots of good nutrients get pulled out, and the large intestine where the bacteria really get to work breaking down plant fiber and sending healthy chemicals our way. This is also where most of the water gets removed and put back in the body, leaving just the waste to poop!
For more information about nutrition for parents, children and educators, please see Healthy Eating Plate.
- Model of the human body and/or doll with anatomical features
- Dissolvable paper or tissue paper and 1-3 tablespoons water
- 2 Saltines and water, vinegar and baking soda
If using tissue or dissolvable paper:
- Cut up some tissue paper or dissolving paper and have children draw their favorite foods on it
- Distribute Ziploc or sealable baggies to each student or group and explain the bag is like the stomach – a muscle that squeezes the food
- Have each student or group add about 1/4 cup of water to the bag. The water will represent our digestive juices/gastric acid
- Pretend the paper is going through the digestive system, completing each action and describing it using the table below for guidance:
|What happens to our food?||What to do with the paper:|
|First, it gets crushed up by your teeth and tongue.||Crumple up the paper! Tear it up!|
|Then it goes through a tube in your throat called the esophagus toward your stomach.||Put the paper into the Ziploc bag and seal it up! Make sure the bags are tightly sealed.|
|While the food is in your stomach, your body’s gastric acid breaks the food down to get the nutrients out of it.||Have the students gently squeeze the bags with the paper. Make observations!|
5. The crushed food is now liquid and is ready to move into the small intestine where the nutrients are absorbed into the blood stream
*To perform this activity with Saltine crackers:
- Give each student or group a Ziploc bag, representing the stomach, a muscle that squeezes the food
- Have them pour 1/4 cup of water, 1tsp of vinegar and 1/2 tsp of baking soda into the bag. This mixture will represent our digestive juices or gastric acid
- The students will add two cracker into the bag with the liquids
- After initial observations, have the students begin to gently squeeze the bag for two minutes. Make sure the students’ bags are tightly sealed.
- Ask, “What is happening to the crackers? What role is the vinegar playing? Is the vinegar like the digestive juices in the stomach?”
- Explain that the crackers are now turning to liquid due to the vinegar and because they squeezed the bag.
- Squeezing the bag is similar to the mechanical churning of food in the stomach.
- The crackers are now a liquid and the nutrients it contains are ready to be absorbed from the small intestine into the blood stream
As with all activities, adult supervision is strongly recommended.
- What does it mean for our gastric juices to be acidic? What is an example of something else acidic) (orange juice, lemon juice)
- What happened during the process of digestion?
- Look at the work of Italian painter Giuseppe Arcimboldo, who used fruits to depict his subjects. Use stickers or drawings of healthy fruits and vegetables to represent different parts of the digestive system
- Have the students pretend they are an apple, and write 5-6 sentences about their journey through each part of the digestive system. Be sure they include simple statements about the digestive action specific to each area:
- Chewing in the mouth to break down the apple.
- Mushing and churning up apple in the stomach
- Squirting apple with digestive juices in the stomach to break it down
- Apple pieces are liquid now and move into the small intestine where they can be absorbed into the bloodstream.
- Large intestine gets rid of extra water and undigested fiber in apple.
Check it Out!
The Dynamic Digestive System: How Does My Stomach Work? (Slim Goodbody’s Body Buddies) by John Burstein (Ages 8+)
This book gives a fun and factual description of the stomach. It is scientifically accurate and has great illustrations, and includes an easy to understand nutrition section.
The Quest to Digest by Mary K. Corcoran (Grades 1-7)
Humorous text and colorful illustrations follow an apple’s journey at each stage of digestion through the human body.
Science Heroes – Digestive System for Kids – a fun game that engages kids with the digestive system (free in the App store)