Heart & Lungs
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flagWhat you'll discover
- arrow_forwardTrace the path of blood through the heart and lungs
- arrow_forwardExplain why heart rate and breathing rate rise during exercise
- arrow_forwardDescribe the roles of arteries and veins
- arrow_forwardConnect oxygen delivery to every cell in the body
A pump that never rests
Your heart is a hollow muscular pump about the size of your fist, tucked slightly left of the centre of your chest. It has four chambers: two upper atria that receive blood, and two lower ventricles that pump it out. The right side pumps blood to the lungs to collect oxygen; the left side pumps that oxygen-rich blood out to the rest of the body.
In one day your heart beats around 100,000 times, moving about 7,000 litres of blood through a network of vessels that, laid end to end, would wrap around the Earth more than twice. The simulation lets you see each chamber squeeze in sequence and watch blood (shown red when oxygen-rich, blue when oxygen-poor) circulate.
Breathe in, breathe out
The lungs sit either side of the heart, protected by the ribcage. When you breathe in, your diaphragm pulls down and your ribcage expands, sucking air deep into branching tubes that end in millions of tiny air sacs called alveoli. Each alveolus is wrapped in blood vessels so thin that oxygen slips across into the blood, and waste carbon dioxide slips back out to be breathed away.
You have so many alveoli that, unfolded, their surface would cover roughly half a tennis court — giving your blood a huge area to swap gases. The simulation paces the breathing animation; raise the activity slider and watch both breathing and heartbeat quicken together.
Why exercise makes you puff
When you run or play hard, your muscles burn glucose for energy far faster — and to do that they need more oxygen and produce more carbon dioxide. Your body detects this and responds on two fronts at once: the heart beats faster to push more blood around each minute, and your breathing speeds up to swap the gases more quickly.
That is why a resting heart rate of around 70 beats per minute can leap past 150 during hard exercise, and your breaths climb from about 12 a minute to over 40. Athletes train their hearts and lungs so they can deliver oxygen efficiently even at these high rates — which is why regular exercise leaves you less out of breath over time.