Breathing and gas exchange
Every breath moves oxygen into your blood and carbon dioxide out — a swap that happens across a vast, thin surface deep in your chest.
Part of your national curriculum
- Biology: structure and function: Understand the structure and functions of the gas exchange system and the effects of exercise, asthma and smoking
Lesson overview
What you'll learn in this lesson
Understand the structure and functions of the gas exchange system and the effects of exercise, asthma and smoking
Key learning points
- • The pathway of air
- • Exercise and breathing rate
- • Asthma and smoking
This lesson at a glance
- 26 minutes
- 17 parts to scroll through
- 3 quick checks
- Marked quiz at the end
- Gentle pace: short sittings with pauses
Words to know
Scroll down — the lesson carries on below
Watch & discover
Part 1 of 17
Visual introductionPicture this
Breathing and gas exchange
Every breath moves oxygen into your blood and carbon dioxide out — a swap that happens across a vast, thin surface deep in your chest.
In a nutshell
Understand the structure and functions of the gas exchange system and the effects of exercise, asthma and smoking
Learning cycle
Part 2 of 17
Learning cycle 1 of 2
Part 1 · The pathway of air
A short piece of teaching, then a check to make sure it has landed.
Explore the idea
Part 3 of 17
Learn
The pathway of air
Air travels through the trachea, into two bronchi (one per lung), then smaller bronchioles, ending at millions of tiny air sacs called alveoli. Alveoli have thin walls, a huge surface area and a good blood supply, ideal for gas exchange by diffusion.
Reset break
Part 4 of 17
Pause
That's sitting 1 of 4 done
Stretch, get a drink, look out of the window. There is no timer and nothing is counting down — your place is saved, so you can come back in five minutes or tomorrow.
Explore the idea
Part 5 of 17
Learn
Exercise and breathing rate
During exercise, muscles respire faster, producing more carbon dioxide and using more oxygen. This increases breathing rate and heart rate, delivering oxygen faster and removing carbon dioxide before it builds up in the blood.
Quick check
Part 6 of 17
Quick check
Part 7 of 17
Reset break
Part 8 of 17
Pause
That's sitting 2 of 4 done
Stretch, get a drink, look out of the window. There is no timer and nothing is counting down — your place is saved, so you can come back in five minutes or tomorrow.
Learning cycle
Part 9 of 17
Learning cycle 2 of 2
Part 2 · Asthma and smoking
A short piece of teaching, then a check to make sure it has landed.
Explore the idea
Part 10 of 17
Learn
Asthma and smoking
Asthma causes the airways to narrow and become inflamed, making breathing difficult, especially when triggered by allergens or exercise. Smoking damages the cilia that clear mucus, tars the alveoli walls (reducing surface area) and increases the risk of lung cancer and bronchitis.
Quick check
Part 11 of 17
Reset break
Part 12 of 17
Pause
That's sitting 3 of 4 done
Stretch, get a drink, look out of the window. There is no timer and nothing is counting down — your place is saved, so you can come back in five minutes or tomorrow.
Challenge round
Part 13 of 17
Game · Sort it
Which of these are true?
Drag each card into the right column. Tap a card first if dragging is fiddly.
True
Not true
Challenge round
Part 14 of 17
Game · Fill the gaps
Finish the sentences
Choose the word that belongs in each gap.
Alveoli have thin walls, a huge surface area and a good blood supply, ideal for gas ____ by diffusion.
Challenge round
Part 15 of 17
Game · Recall cards
Why do alveoli have very thin walls and a huge combined surface area?
Card 1 of 4
Mastery quiz
Part 16 of 17
Marked quiz
End of lesson quiz: Breathing and gas exchange
4 questions, marked with the reasoning shown. No timer.
1. Why do alveoli have very thin walls and a huge combined surface area?
2. Where does gas exchange happen in the lungs?
3. Why does breathing rate increase during exercise?
4. How does smoking damage the lungs?
Lesson round-up
Part 17 of 17
Lesson round-up
Ready when you are
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Ask LunaPart 1 of 17 · Watch & discover
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Understand the structure and functions of the gas exchange system and the effects of exercise, asthma and smoking