How the Human Body Works
Explore how your body operates as an interconnected system of pumps, levers, sensors, and chemical messengers. Discover the real mechanics behind everyday sensations like fatigue, reflexes, and appetite. Build a working mental model of how your organs team up to keep you alive and moving.
Like Duolingo, but for How the Human Body Works. Tomo turns the whole topic into a game you play five minutes a day, until it actually sticks.
24 levels across 3 sections, about 48 minutes end to end, roughly 10 days at five minutes a day. It moves through Operating the Machine; Sense, Signal, and Shield; and The Balancing Act. It starts from scratch.
Free forever · No credit card · iPhone & Android
Key ideas in How the Human Body Works
- The heart acts as two connected pumps working side-by-side at the same time
- The right half pumps oxygen-poor blood to the lungs
- The left half receives oxygen-rich blood and pumps it through the rest of the body
- The lungs cannot expand or pull air inward on their own
- The diaphragm muscle pulls downward to create open space and negative pressure inside the chest
- Outside air rushes in to fill the chest cavity vacuum
- The pulse is a mechanical pressure wave traveling along elastic artery walls
- Actual blood cells move much slower than the shockwave of each heartbeat
- Arteries expand and snap back like elastic tubes with every contraction
- The urge to breathe is driven by carbon dioxide buildup, not a drop in oxygen
- Dissolved carbon dioxide makes the blood slightly more acidic
- The brain monitors blood acidity to decide when to speed up breathing
- Blood vessels widen in working leg muscles to deliver extra oxygen and energy
- Blood vessels narrow in resting digestive organs to divert supply elsewhere
- The total volume of blood stays the same, so diameter changes steer where it goes
- Muscle fibers can only actively shorten and pull, never push outward
You've tried the other tabs
Thirty open tabs. Four facts you actually kept.
You watched. You nodded. By Sunday it was gone.
One answer, then back to scrolling.
Eight weeks. You meant to finish. You didn't.
Tomo gives How the Human Body Works the Duolingo treatment: levels, streaks, and quick quizzes that test what you just learned. That game loop is what the tabs above never had, so it's the one you actually finish.
Here's what playing it feels like
A real question from this course. Take your best guess.
Where does the right half of your heart send its blood?
Get it right to open this lesson and 23 more in the app.
Where How the Human Body Works takes you
- 1
Operating the Machine
- Instant Fuel: Breath and Blood Flow
- Levers and Tension: How We Move
- The Disassembly Line: Breaking Down Food
- 2
Sense, Signal, and Shield
- Fast Circuits: Reflexes and Sensory Input
- Slow Messengers: Hormones and Rhythms
- Defending the Perimeter: The Immune System
- 3
The Balancing Act
- Filtration and Waste: The Clean-Up Crew
- Homeostasis and Repair: Constant Self-Correction
3 sections · 8 units · 24 levels. Built to play, not to enroll.
You pick the voice
How the Human Body Works is taught in the The Bestie style: your friend who just gets it. Want a different feel? In the app you can spin up the same topic in any of Tomo's teaching styles. Same facts, totally different vibe.
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Start How the Human Body Works today.
Download Tomo, search How the Human Body Works, and play your first lesson in under a minute.