How the Human Body Works
Discover the mechanical and chemical wonders powering your everyday life. Learn how muscles, organs, and nerves coordinate in real time to keep you moving, fueled, and alive.
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.
A short one: 12 levels across 2 sections, about 24 minutes end to end, roughly 5 days at five minutes a day. It moves through The Daily Engine in Motion and Maintaining Balance and Control. It starts from scratch.
Free forever · No credit card · iPhone & Android
Key ideas in How the Human Body Works
- Muscle fibers can only actively contract and pull; they have no mechanism to push outward
- Joints rely on antagonistic muscle pairs situated on opposite sides to reverse any movement
- Bones act as rigid levers pivoting around joints, which function as fulcrums
- Muscles attach close to the fulcrum, trading brute mechanical force for greater reach and hand speed
- Tendons connect muscle to bone, acting as durable cables that deliver pulling force
- Ligaments connect bone directly to bone, limiting excessive joint movement to prevent dislocation
- Muscle fatigue acts as a protective safety brake managed in large part by the nervous system
- The brain and motor nerves dampen signals to working muscles well before cellular fuel reserves reach absolute zero
- Upright posture is an active balancing act powered by continuous micro-contractions, not static joint locking
- Deep core and spinal stabilizing muscles make constant subtle adjustments to keep the body's center of gravity upright
- Mechanical chewing and stomach churning break food into a slurry, but chemical digestion is what breaks large nutrient polymers into microscopic molecules
- The wall of the small intestine acts as a cellular barrier that only lets individual small molecules, like simple sugars and amino acids, pass into capillaries
- Lungs contain millions of microscopic air sacs called alveoli that provide an enormous, paper-thin surface area
- Oxygen moves across alveoli walls into adjacent blood vessels passively by diffusion, not through muscular pumping inside the lung tissue itself
- The heart is divided into two separate pumps operating in tandem
- The pulmonary circuit routes low-oxygen blood to the lungs to pick up fresh oxygen and shed carbon dioxide
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.
Your biceps contracts to bend your elbow. What has to happen to straighten your arm back out?
Get it right to open this lesson and 11 more in the app.
How to learn How the Human Body Works, step by step
Go in order. 12 short levels across 2 sections, about 24 minutes in all, five minutes a day.
- 1
The Daily Engine in Motion
- How Muscles and Bones Create Movement
- The Fuel Line: Processing Energy and Oxygen
- 2
Maintaining Balance and Control
- Autopilot: How the Body Regulates Itself
- The Body's Wiring: Fast Signals and Slow Broadcasts
2 sections · 4 units · 12 levels. Built to play, not to enroll.
Questions about How the Human Body Works
How do I learn How the Human Body Works?
Go in order: start with The Daily Engine in Motion, then Maintaining Balance and Control. On Tomo that's 12 short levels, about 24 minutes in all, played five minutes a day. Start free and play the first level in under a minute.
Is there a Duolingo-style app for How the Human Body Works?
Yes. Tomo works like Duolingo: short daily lessons, streaks and quick quizzes. How the Human Body Works is one of its free courses, and you can type any other topic to get a course of your own.
Is the How the Human Body Works course free?
Yes. How the Human Body Works is playable on Tomo's free plan, which doesn't expire. No credit card, no waitlist. Download the app and start your first lesson.
How long does it take to learn How the Human Body Works?
12 levels across 2 sections, about 24 minutes of play in total. It's built for five minutes a day, so you finish it a little at a time instead of all at once.
Do I need any background to start How the Human Body Works?
No. It's pitched at a beginner level, so it starts where you are and builds up. If you can tap a phone, you can start.
Tomo is in ChatGPT
Tomo is also a ChatGPT plugin: the same playable courses, built and played inside your chat.
Add Tomo to ChatGPT- What to ask
- “Make me a Tomo course on black holes.” “Turn this chat into a Tomo course.”
- What you get
- Quick questions with instant feedback, hearts and stars, ready to play in about a minute.
- Where it goes
- No sign-up to start. Connect your Tomo account and your streak carries on in the app.
You pick the voice
How the Human Body Works is taught in the Professor style: clear, structured, thorough. 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.