Question

The human small intestine is 20 feet long and a little over an inch in diameter (about 3.5 inches in circumference on average), but has about 2,700 square feet of absorptive surface area, about the size of a small tennis court. If it didn’t have the folding and microfolding, how long would the small intestine have to be to have the same surface area? Do your calculations here:

Answer 1

The small intestine is in the shape of a cylinder.

Lateral surface area of a cyclinder = 2πrh = Circumference * height
where r= radius of cylinder; h = height or the length of the cylinder.

Absorptive surface area of small intestine= 2700 square feet
Circumference = 3.5inches = 3.5/12 ft
Height (h) = 20feet

If there were no folds on the surface area of the small intestine, then , new Height would be H.

Thus, lateral surface area of small intestine without folds = total absorptive surface.
Thus, 2πrH = 27000
or, H = 27000/ (2πr) = 2700/ (3.5/12) feet = 9257.14 feet

Thus, the small intestine would have to be approximately 9257.feet to have the same absorptive surface area if it did not have foldings or microfoldings.