Your enormous surface area... Area

Area per volume

The idea: You've an enormous surface (~400 m2, with skin merely ~2 m2). With it, you defuse, food and oxygen, with your environment. Just like all other cellular life. But your surface is easily forgotten, tucked away inside you as lungs and intestine. Here is a reminder...

Lungs as sheet skin as box Intestines as sheet Person is ~1.5 m tall.

Lungs and intestine sheets are paper-thin.

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