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Digestive System Exploration - it’s lit.
7th grade (Could work for 9th - 12th)
4 students (Can work with groups of 6 to save material cost)
biology, life science
We all have heard of proteins, fats and carbohydrates, but how do we actually extract these from our turkey sandwich? Students will learn about the digestive system and how it helps break down all of the various foods we eat into usable molecules! Using different colored LEDs and hand drawn pictures, they will create diagrams of the digestive system that help display where each molecule is broken down.
digestive system, 3D digestive system, modeling, nutrition, life science, Arduino
The basics of Arduino, how to code a SparkFun RedBoard, the anatomy of an LED
Introduction / Motivation:
Today, we are going to start a project that involves food! I bet that got your attention! More specifically, we are going to talk about how food is broken down by the body. Most of us are familiar with the terms “carbohydrates, proteins and fats”. These are the main things that constitute food, with some minerals and vitamins as well. We know that we need things like carbohydrates for energy, and proteins to help our muscles grow, and fats for brain health and other functions, but does anybody know how our body actually extracts these molecules from food? (Answers may vary between “in our mouth!” to “it turns it into poop!” Be prepared.)
All of this is part of a process called “Digestion”. (Write the word up on the board) Digestion consists of two sub-processes. One is “Physical” (Write this word up) which includes when we chew our food. Can anybody guess the second one? (Answer might be “digesting” or “extracting”. Looking for “Chemical”) Yes, “Chemical!” (Write the word up). The physical portions of our digestion are pretty simple! We chew our food so that it is easier to swallow, yes, but we also chew food so that the Chemical process is faster!
Think of it this way, (Get water cups out and place on a table where all can see), I have two forms of Alka Seltzer (show wine glasses of the Alka Seltzer), one is crushed up and one is a whole tablet. I want you to all watch as I pour these into separate glasses. First we will observe, then we will hypothesize. I want you to determine which one will dissolve faster (Pour the alka seltzer in, let each one finish bubbling.) So which one was it? (All should answer the crushed up/powdered form) Yes! That’s correct. Our body does the same thing. When we chew our food, we increase the “surface area” which is how much of the food is exposed to our stomach acid and other things, so it will digest faster. And our stomach actually does this weird act of compressing and squeezing to help crush the food into smaller parts. This is also an example of physical digestion.
We also need to know which organs in our bodies are responsible for aiding in our chemical digestion. We need to communicate this information in a way that is easy to understand. If you think of a museum exhibit, there is often a lot of Engineering and Design that goes into communicating information in a simple way. This will be your challenge: To communicate which molecules are broken down in each organ that aids in digestion.
You should be familiar with how to splice wires yourself using the NASA method. This is a tough skill to learn and should be practiced on a few different wires to learn the method. In addition, familiarity with for loops is highly suggested as almost every event uses a for loop. Be aware of common mistakes that students make when using for loops.
Before the Activity
With the Students
Correct way to wire an LED using the NASA Splice. Note that mine is not perfect (there are gaps between loops and I did not trim the ends and there are not at least 3 turns)
This is okay - students don’t need perfect splices. Also note the semi flat edge on the right side of the LED. This corresponds with the negative leg, the short leg, of the LED. If you are not sure if they wired their wires correctly, look for this flat edge to indicate which leg is the negative.
Organs laid out and holes for LEDs marked and punched through. Their diagram should resemble something like this.
Close up of the servo attached to the stomach cutout using tape. Also notice that the lip of the servo is larger than the hole it sits in.
Close up of connecting jumper wires to the Servo. It seems like you may be harming it but make sure the jumper wires are pushed in firmly.
Circuit diagram of the entire display. Note the color codes, black is negative, yellow is positive.
A for loop is a way to tell the Arduino to do something a certain number of times. In this example, the Arduino will count from 3 to 8 (because when i=9 the loop is no longer true and it exits). Inside of the for loop it turns any LED attached to pins 3-8 off and declares them as outputs.
Going Further: There are many ways to take this activity further! Currently, the LEDs only light up to show what molecules are broken down in which locations. There is no indication of what enzymes are present and we stop short of talking about the body absorbing nutrients in the small intestine.