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Analyzing how different body systems cooperate to keep us alive and active.
Have you ever wondered why your heart thumps like a drum and your breath comes in quick gasps the moment you start running? It’s because your body is actually a giant team of superheroes working together to keep you moving!
Your body needs oxygen to survive, but getting it to your toes is a two-system job. The Respiratory System (lungs) brings oxygen into your body when you inhale. However, the lungs can't move that oxygen to your muscles by themselves. That is where the Circulatory System (heart and blood) takes over. Think of your lungs as a loading dock and your blood as a fleet of delivery trucks. The oxygen hops into the blood, and the heart pumps it through tubes called vessels to every cell in your body. Without this teamwork, your cells would never get the air they need to function!
Quick Check
Which system acts like the 'delivery trucks' to move oxygen from the lungs to the rest of the body?
Answer
The Circulatory System.
Just like a car needs gasoline, your Muscular System needs fuel to move. This fuel comes from the food you eat! The Digestive System breaks down your snacks into a simple sugar called glucose. Once the food is broken down, the nutrients are absorbed into the blood. The circulatory system then carries this glucose 'fuel' to your muscles. When you jump or run, your muscles 'burn' this glucose to create energy. This is why you might feel hungry after a long day of playing—your muscles have used up all the fuel provided by your digestive system!
Let's look at how an apple becomes a jump: 1. You eat an apple (Digestive System). 2. The apple is turned into type of sugar called glucose. 3. The blood carries that glucose to your leg (Circulatory System). 4. Your leg muscle uses the glucose to contract and jump (Muscular System).
Quick Check
What is the name of the sugar that the digestive system provides to muscles for energy?
Answer
Glucose.
When you start to exercise, your muscles suddenly need more oxygen and more fuel than they did while you were sitting down. Your brain notices this and sends a signal to speed everything up. Your heart rate increases to pump blood faster, and your breathing rate increases to bring in more oxygen. It is a perfectly timed reaction! If your heart beats at beats per minute while resting, it might jump to or more during a race to keep up with the demand. All these systems work in harmony to make sure you don't run out of steam.
Imagine your resting heart rate is beats per minute. When you sprint, your heart rate increases by beats. 1. Identify the resting rate: . 2. Add the increase: . 3. The new active heart rate is beats per minute. This shows the circulatory system working harder to support your muscles!
Why do marathon runners eat a big pasta meal the night before a race? 1. Pasta is full of carbohydrates that the Digestive System turns into glucose. 2. The body stores this extra fuel. 3. During the race, the Circulatory System constantly delivers this stored fuel and fresh oxygen (from the Respiratory System) to the legs. 4. If any one of these systems slows down, the runner 'hits the wall' and feels like they can't move.
Which two systems work most closely together to get oxygen to your leg muscles?
What happens to your breathing rate when you exercise?
The muscular system can move on its own without help from any other system.
Review Tomorrow
In 24 hours, try to explain to a friend how an apple you eat eventually helps you run a race.
Practice Activity
Count your pulse for 15 seconds while sitting. Then, do 20 jumping jacks and count it again. Notice how your circulatory system responded to the movement!