In just under 30 seconds, your blood circulates (moves) through your entire body, reaching every single one of your trillions of cells! As you already know, your cells need oxygen and nutrients to function, and they make waste products like CO2. Your blood is responsible for both delivering the oxygen and nutrients, and picking up the waste. They do this by traveling through a closed system of tubes called blood vessels. There are three types of blood vessels: arteries, veins, and capillaries.
Each beat of your heart sends blood through your arteries, veins, and capillaries. Day and night, your heart’s rhythmic contractions send blood and nutrients to each of your trillions of cells. This is a non-stop process. Every minute of every day, your heart pumps about 4 liters of blood. However, since your heart is only about the size of your fist, it can only pump about 5 ounces of blood with each beat.
Use the activities below to learn more about how your heart works with your circulatory system to get blood to all of your cells. You might also be surprised to find out how hard your heart works for you as you complete parts 2 and 3!
Part 1 - Blood flow through the Heart
Print "The Heart: Connect the Dots" handout linked below, and use the attached image (gif) to help you label your heart and describe the blood flow.
Step 1:
Deoxygenated blood from the body enters the heart through the superior and inferior vena cava. It’s first stop in the heart is the right atrium.
Step 2:
Almost instantly, the blood gets pushed into the right ventricle.
Step 3:
The blood then exits the heart through the pulmonary artery as it heads towards the lungs to pick up oxygen.
Step 4:
The newly oxygenated blood re-enters the heart from the lungs through the pulmonary veins. It's first stop is the left atrium.
Step 5:
The blood then flows through the left ventricle.
Step 6:
Finally, the blood is pumped out of the heart through the aorta as it heads back out to the body.
Part 2 - Measuring your heart rate
How fast does your heart beat? It depends on several things such as age, activity level or how calm/excited you are. When body movement increases, the cells need more nutrients and oxygen (for cellular respiration). As a result, the heart will beat faster to keep up with the demand. When your physical activity decreases, the heart rate will decrease.
Part 3 - Flexing your muscles
Age, activity level, and even how calm or excited you are can affect your heart rate. Consequently, the range of “normal” heart rates for 12-16 year olds is 60 - 110 beats per minute. Each beat uses about the same amount of force that it would take to squeeze a tennis ball.
Task: You are going to find out how easy/hard it is to keep up with your heart. You will need a tennis ball (or something very similar) and a partner for this activity.
Instructions: Squeeze the tennis ball as hard as you can as many times as you can for 1 minute. Have your partner time you while you count. Record how many times you successfully squeezed the tennis ball hard enough to cause a noticeable indent. Switch roles with your partner. Were either of you able to squeeze the tennis ball at least 60 times? Probably not (unless you were using a really old, squishy ball), but don't feel bad! Your heart is a very specialized muscle!
Bonus
Challenge yourself to learn how doctors diagnose patients with heart conditions. You will get to see the various tests and tools doctors use, and help interpret the results. Use the "Cardiology Lab" link below to open the interactive and get started.