Bringing maker education and computational thinking to the classroom.
Get Your Heart Racing!
7th grade (Can work for 9th-12th)
Groups of 2 - 3
life science, biology
Students studying biology and life science are always keen to know how the body works - and it all comes down to bloodflow. Students are learning how the heart keeps the blood flowing using a 4 chamber pump that takes de-oxygenated blood (blood that’s been used) and pushes it through the lungs to re-oxygenate it. The 4 chambers must work in perfect synchronization and if the heartbeat is too fast or too slow, this can lead to problems. Tachycardia and Bradycardia are two medical conditions that mean a heartbeat that is too fast or too slow, respectively, and identifying these can help students understand how the body tries to maintain homeostasis. They are using buttons to try and return the heartbeat to baseline by engaging various “body systems” to return the heartbeat to a homeostasis. If they choose wrong, the heartbeat may get out of control!
circulatory system, homeostasis, heart function, blood, pumps, tachycardia, bradycardia, heartbeat
Please make sure you have done at least 1 or 2 Arduino lessons with your class beforehand. Ideally, Project 1A: Blinking an LED and Project 2B: Digital Trumpet from the SparkFun SIK 4.0 Guide. If you really want students to excel, completing the entirety of Project 2 from the SparkFun SIK 4.0 will greatly aid them.
Introduction / Motivation:
Today we are going to be getting our blood flowing! Mostly just to our brains with all the amazing learning we are about to do. Does anybody in the class know how blood is moved throughout our body? (Possible answers include “pumps”, “the heart”, “gravity” and more). Yes, the heart is responsible for moving our blood and it does pump but how does it do that? (Possible answers may be that it “beats” or “like a car” or others) The heart does beat, but the way it moves blood through the body is by pushing more blood behind it. This forces the blood to move forward because it is a “closed system.” A closed system (write this up on the board) is one in which the blood vessels are FULL of blood, so much so that any new blood would add pressure to the system. Blood taken away, reduces the pressure! So when the heart “beats” it pushes blood out of the heart and into the arteries, which then push blood down the line until blood that was just outside of the heart now enters the heart.
The way the heart “beats” is by using muscles! The heart is composed of muscle fibers that “contract” like a bodybuilder flexing their biceps. Think of it like having a balloon full of water and then squeezing the balloon. The pressure inside of the balloon increases, causing the water to flow out! But the heart is not just one big water balloon, it’s actually a series of 4 smaller water balloons. Some of these balloons are even connected to each other! In order for us to live a healthy life, these little balloons must keep their rhythm, or timing, perfectly. The heart has various systems that are meant to keep this timing in check - which is called “homeostasis.” (Write this on the board)
Homeostasis is a natural “resting” state of the body. Homeostasis is also incredibly different for everybody. If we all were to find our “resting” heart rate, which is where we are just sitting in a relaxed state, we would find that we all have different heart rates. There are certain systems in our body that will speed up our heart rate. Adrenaline, for instance, may be released when you watch a scary movie as your body is reacting and preparing itself for a lot of strenuous activity which would require a lot of oxygen. The faster your heart rate, the more oxygen that is being delivered to your muscles per minute. Knowing that, do you think athletes have a lower resting heart rate or a higher resting heart rate than others? (Answers will probably be higher) Not true! Theirs is actually lower, because their heart is trained, making it capable of pushing out more blood per contraction, which means it does not need to beat as fast! And meditation may slow down our heart rate.
So today, we are going to build a “heart” and add some buttons that will make our heart beat faster or slower based on external stimuli. These are called “feedback mechanisms” and some are positive (enhance an already changing state) and some are negative (returning the state to homeostasis.) We will be focusing on the positive loops to show how they change the heart rate!
The teacher should be familiar with the systems of the body, and the code required to blink LEDs using the Arduino or SparkFun RedBoard. Lastly, they should understand the common pitfalls and troubleshooting tips below as it relates to how buttons function in the Arduino code environment.
Before the Activity
With the Students
These chambers will fit over the LEDs that are placed by students. One thing to watch out for is the tall jumper wires can get in the way, students may carefully bend the jumper wires to allow this to fit over top.