Heart, lungs and the oxygen delivery system
Sustained exercise is a supply problem: how much oxygen can you move from the air to a working muscle every minute, and how fast can you clear the waste?
Part of your national curriculum
- Health and fitness: Develop components of fitness through sustained physical activity, understanding the effects of exercise on the body
Lesson overview
What you'll learn in this lesson
Develop components of fitness through sustained physical activity, understanding the effects of exercise on the body
Key learning points
- • Cardiac output = heart rate x stroke volume
- • Breathing and gas exchange
- • Short-term effects you can measure
- • Long-term adaptations
This lesson at a glance
- 22 minutes
- 19 parts to scroll through
- 4 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 19
Watch first
Heart, lungs and the oxygen delivery system
Follow oxygen from the alveoli to a working muscle as effort rises.
In a nutshell
Develop components of fitness through sustained physical activity, understanding the effects of exercise on the body
Learning cycle
Part 2 of 19
Learning cycle 1 of 2
Part 1 · Cardiac output = heart rate x stroke volume
A short piece of teaching, then a check to make sure it has landed.
Explore the idea
Part 3 of 19
Learn
Cardiac output = heart rate x stroke volume
Stroke volume is the blood pumped out of the left ventricle each beat; heart rate is beats per minute. Multiply them and you get cardiac output, the litres of blood per minute reaching the muscles. At rest a learner might have a stroke volume of 70ml and a heart rate of 70bpm, so cardiac output is about 4.9 litres per minute. In hard exercise both rise, and cardiac output can more than quadruple.
Reset break
Part 4 of 19
Pause
That's sitting 1 of 5 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 19
Learn
Breathing and gas exchange
Air travels trachea, bronchi, bronchioles, alveoli. At the alveoli, oxygen diffuses into the blood and carbon dioxide diffuses out, driven by concentration gradients. Exercise raises both breathing rate and tidal volume (the air moved per breath), so minute ventilation climbs sharply. Rising carbon dioxide in the blood — not falling oxygen — is the main signal that makes you breathe harder.
Quick check
Part 6 of 19
Quick check
A performer has a stroke volume of 80ml and a heart rate of 150bpm. What is their cardiac output?
Quick check
Part 7 of 19
Reset break
Part 8 of 19
Pause
That's sitting 2 of 5 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 19
Learning cycle 2 of 2
Part 2 · Short-term effects you can measure
A short piece of teaching, then a check to make sure it has landed.
Explore the idea
Part 10 of 19
Learn
Short-term effects you can measure
Within seconds: heart rate rises, breathing deepens, blood is redistributed towards working muscle (vascular shunting) and away from the digestive system. Within minutes: body temperature rises, sweating starts, skin reddens as vessels near the surface widen to lose heat. These are normal responses, not warning signs — the warning signs are dizziness, chest pain or a heart rate that will not settle in recovery.
Explore the idea
Part 11 of 19
Learn
Long-term adaptations
Months of endurance training produce cardiac hypertrophy: a stronger left ventricle with a larger stroke volume. Because each beat delivers more blood, resting heart rate falls — bradycardia. Capillary networks around muscles and alveoli grow, so gas exchange improves, and recovery heart rate drops faster after effort. Recovery rate is one of the clearest signs that a training programme is working.
Reset break
Part 12 of 19
Pause
That's sitting 3 of 5 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.
Quick check
Part 13 of 19
Quick check
Part 14 of 19
Challenge round
Part 15 of 19
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
Reset break
Part 16 of 19
Pause
That's sitting 4 of 5 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 17 of 19
Game · Recall cards
Which activity best develops cardiovascular endurance?
Card 1 of 4
Mastery quiz
Part 18 of 19
Marked quiz
End of lesson quiz: Heart, lungs and the oxygen delivery system
4 questions, marked with the reasoning shown. No timer.
1. Which activity best develops cardiovascular endurance?
2. Which joint type allows rotation as well as flexion and extension?
3. During the upward phase of a press-up, the triceps is acting as the:
4. A 5000m runner is likely to have a high proportion of which fibre type?
Lesson round-up
Part 19 of 19
Lesson round-up
Ready when you are
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Ask LunaPart 1 of 19 · Watch & discover
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Develop components of fitness through sustained physical activity, understanding the effects of exercise on the body