Your Small Intestine Is NOT a Tennis Court

Your small intestine is only about six meters long, yet it absorbs almost everything you eat. How?

A smooth tube that size would have barely any surface to soak up nutrients. So how does it grab enough from your food to keep you alive?

The answer is folding, stacked three levels deep. First, the inner wall is thrown into big ridges. Second, every ridge is carpeted in millions of tiny finger-like bumps called villi. And third, each of those villi is covered in smaller bristles called microvilli. Each layer multiplies the surface, so a short tube ends up with dozens of times the area of its bare walls.

You have probably heard this surface is the size of a tennis court. That figure is a myth. Careful measurements put it closer to a small studio apartment, around thirty to forty square meters. Still astonishing for a tube a few meters long.

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