The numbers
100,000heartbeats a day
~2,000gallons pumped a day
60,000miles of blood vessels
98.6°Fheld steady by feedback
Red blood cells live about 120 days, and your body makes millions every second.
An engineer's view
| Body system | Engineering match |
|---|---|
| Heart and blood vessels | Pump and piping network |
| Lungs | Gas exchanger |
| Kidneys | Filtration plant |
| Nerves | Wiring and signals |
| Immune system | Security and threat detection |
Each system is controlled and monitored around the clock.
A feedback loop: body temperature
- Sensors detect a changeSkin and brain notice you're too hot
- The controller decidesThe hypothalamus compares to the set point
- Actuators respondSweating and wider blood vessels release heat
- Back to normalThe response eases off as you cool
Homeostasis
Keeping conditions steady inside the body, just like a thermostat.
Sources: National Institutes of Health; American Heart Association
Remember
Your body runs on feedback control: sense, compare, correct, every second of your life.
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Answer key
- About how many times does the heart beat each day?100,000Roughly 100,000 beats a day.
- What does homeostasis mean?Keeping conditions in the body steadyIt's the body's way of holding things stable.
- Which part of the brain acts as the body's thermostat?HypothalamusThe hypothalamus controls body temperature.
- Which organ works like a filtration plant?KidneysKidneys filter blood and remove waste.
- About how long does a red blood cell live?120 daysAbout 120 days.