The Respiratory System: How We Breathe
Atlas the friendly explorer points to labeled arrows on a giant see-through lung model, showing glowing blue oxygen flowing in one side and gray carbon dioxide drifting out the other, while speaking directly to the learner.
- Identify the two gases exchanged by the lungs: oxygen in and carbon dioxide out.
- Sequence the steps of one breathing cycle from inhale to exhale.
- Match each gas to its role: oxygen as fuel delivery and carbon dioxide as waste removal.
- Distinguish the correct gas-direction pair from common mix-ups.
Key terms
- respiratory system
- the body parts that help you breathe
- lungs
- two air bags inside your chest
- oxygen
- the gas your body needs for energy
- carbon dioxide
- the waste gas you breathe out
- breathe
- to pull air in and push it out
Breathing Oxygen In
When you breathe in, your lungs pull in fresh air. That air carries a gas called oxygen. Your whole body needs oxygen to work and to give you energy. Your muscles, your brain, and even your toes use it. Your lungs grab the oxygen from the air and pass it into your blood. Then your blood delivers the oxygen everywhere it is needed.
Breathing Waste Out
As your cells use oxygen to make energy, they make a waste gas called carbon dioxide. Think of carbon dioxide like trash your body needs to throw away. When you breathe out, your lungs push that carbon dioxide back into the air. So your lungs do two jobs, taking in the oxygen you need and pushing out the carbon dioxide waste, all day and night.
Worked examples
What do your lungs do in one breath?
- You breathe in and your lungs pull in air with oxygen.
- Your lungs pass the oxygen into your blood.
- You breathe out and push carbon dioxide away.
Answer: Lungs take in oxygen and push out carbon dioxide waste.
Activity
Match each gas card to what it does when you breathe in or breathe out.
Practice
What gas do your lungs take in for energy?
What waste gas do your lungs push out?
Common mistakes to avoid
- We breathe out oxygenWe breathe in oxygen and breathe out carbon dioxide waste.
- Lungs make oxygenLungs collect oxygen from the air; they do not make it.
Check your understanding
What gas do your lungs take IN that your body needs to work?
When you breathe OUT, what waste gas does your body get rid of?
A friend says, 'We breathe in carbon dioxide and breathe out oxygen.' Is that correct?
Recap
Your respiratory system uses your lungs to breathe. The lungs take in oxygen that your body needs for energy and push out carbon dioxide waste, in and out all day and night.
Reflect
Take a deep breath and feel oxygen coming in!