Lungs

Tap for a deep breath. Hands-on: squeeze them and they breathe out; let go to refill.

The lungs are two spongy organs in the chest that bring air into the body. Air comes down the windpipe, splits into two tubes and branches into smaller and smaller airways that end in millions of tiny air sacs, where oxygen passes into the blood and carbon dioxide passes out.

These lungs breathe gently by themselves. Tap for a deep breath: both lungs swell out big, hold, then empty further than usual and settle back into their rhythm. The Breath slider sets how deeply they breathe at rest. An adult at rest takes about 12 to 20 breaths a minute. With ✋ Hands-on on, press and hold them (or pick them up) and they breathe out; let go and they fill again, a little past rest, then breathe gently on.

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