Breathing and gas exchange · System
Exercise, asthma and smoking
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A reliever inhaler helps someone having an asthma attack.
If you had to guess, does the puff from the inhaler contain extra oxygen?
No oxygen at all. The inhaler relaxes the muscle in the bronchioles, so the airways open.
No oxygen at all. The inhaler relaxes the muscle in the bronchioles, so the airways open.
Key words
A condition in which the bronchioles narrow. The muscle contracts, the lining swells and extra mucus is made.
- bronchioles
Tiny moving hairs on the airway lining that sweep mucus up and out of the lungs.
A gas that binds to haemoglobin far more strongly than oxygen does and does not readily let go.
Key knowledge
When you exercise, your muscles respire faster.
They need more oxygen and make more carbon dioxide.
Your brain detects the rising carbon dioxide in your blood.
Your breathing gets faster and deeper. Your heart rate rises too.
This delivers more oxygen and removes more carbon dioxide.
These changes reverse after you stop.
In an asthma attack, the bronchioles get narrower.
The muscle in their walls contracts.
The lining swells and makes more mucus.
Less air can get through to the alveoli.
A reliever inhaler relaxes the muscle, so the airways open again.
What is in cigarette smoke
| Row | What it does | The result |
|---|---|---|
| Tar | ||
| Carbon monoxide | ||
| Nicotine | ||
| Particulates and heat |
Smoking damages the walls of the alveoli. This disease is called emphysema.
The surface area for gas exchange falls.
This damage is permanent.
What recovers
| Row | What changes | Recovers |
|---|---|---|
| Exercise | ||
| Asthma attack | ||
| Carbon monoxide | ||
| Cilia | ||
| Alveoli walls |
Wrong: Being out of breath means your lungs cannot hold enough air.
Right: Your body is responding to rising carbon dioxide.
Wrong: In an asthma attack there is not enough oxygen in the air.
Right: The air is the same. The airways have narrowed.
Key fact
Exercise raises breathing rate, and this reverses after you stop. In an asthma attack the airways narrow, and treatment can open them again. Smoking destroys the walls of the alveoli, which permanently reduces gas exchange.
Practice
Not started yet.
Rungs 3 and 4 you mark yourself.
Rung 1
What does your body actually detect that makes you breathe faster during exercise?
Rung 2
Which of these effects of smoking is permanent?
Rung 3
Explain why a reliever inhaler helps during an asthma attack even though it contains no oxygen, and why giving someone oxygen instead would not fix the underlying problem.
Rung 4
A patient with emphysema has almost normal lung volume but greatly reduced gas transfer. Explain how both can be true, using what you learnt about alveoli. Say which feature of a good exchange surface has been lost.
Your blood still holds extra carbon dioxide when you stop.
After hard exercise, your body also needs oxygen to break down lactic acid.
You keep breathing hard until this is done.
The air already holds plenty of oxygen.
The problem is the narrow airways, so less air can get through.
A reliever inhaler treats that by opening the airways.
In emphysema, the walls between alveoli break down.
The lungs still hold about as much air.
But the surface area is much smaller, so gas exchange is poor.
Before this lesson
- This follows on from Alveoli: built for exchange.
Connects to
- Stomata and gas exchange in plants
- Alveoli: built for exchange
- Antagonistic muscle pairs
Muscles can only pull, so they work in pairs.
At GCSE this becomes
- Risk factors for non-communicable disease, correlation and cause, and the effect of exercise on respiration.
Where to next
Ask MrBadmus
Want to check which part of the system each factor affects?
If any of this is about you or someone you know, talk to someone you trust — a parent or carer, a teacher, your school nurse, a pharmacist or your GP. Out of school hours: Childline — 0800 1111, free and confidential.
This lesson describes the biology of asthma and of smoking. It is not medical advice and does not replace an asthma plan: if you have asthma, follow the plan your doctor or nurse gave you, and treat a reliever inhaler that is not working as an emergency. For help stopping smoking, a GP or pharmacist is the right place to start.
Lesson content © MrBadmus.