Circulation & Breathing Together
Understand how the circulatory and respiratory systems work together: the lungs oxygenate the blood, the heart pumps it around the body, cells use the oxygen and produce carbon dioxide waste, and the blood carries the waste back to the lungs to be breathed out
What a learner can do afterwards
- Describe the cycle: lungs add oxygen to blood → heart pumps oxygenated blood to body → cells use oxygen → blood returns carbon dioxide to lungs
- Explain why heart rate and breathing rate increase during exercise (muscles need more oxygen)
- Measure their own resting and post-exercise heart rate and explain the difference
1 · Read
When you run, your leg muscles need more oxygen to keep going. Your respiratory system and your circulatory system work as one team to deliver it. Air reaches your lungs, and oxygen passes into the blood there. Your heart pumps that oxygen-rich blood out to cells all over your body. The cells use the oxygen and make carbon dioxide waste, and the blood carries that waste back to the lungs to be breathed out.
Zara starts jogging. Her leg muscles burn fuel fast and need more oxygen. Her heart pumps faster to rush oxygen-rich blood to those muscles, and her lungs breathe faster to bring in more oxygen and clear out the extra carbon dioxide.
When your muscles work harder, they use up oxygen faster and make more carbon dioxide waste. That is why your heart rate and your breathing rate climb together during exercise, not just one of them.
Lungs, heart, and cells work as one team: oxygen goes in, carbon dioxide goes out, and exercise speeds up the whole cycle.
The rewritten readings were written for this dataset.
2 · Watch
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8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.