Powerhouses In The Body: The Muscles Acar has one single engine.
Airplanes often fly with two or four. How many “engines” enable
you to hold this book in your hand, or to take a single step?
Whatever you may be doing, countless microscopic engines produce
the power necessary for you to perform that action. The engines
in question are your muscle fibers. There are more than 6
billion of these tiny engines in your body, which allow you to
drink, drive, walk, speak, allow your heart to beat, your
eyelids to blink, and let you eat and turn your head. Even as
you read these lines, the movement of your eyes takes place
thanks to the energy produced by these tiny motors. The size of
the muscle cells depends on where they are used. Some may be no
more than 1/100,000th of a centimeter in size, whereas others
can be 3 centimeters (1.18 inches) long. 73 These tiny muscle
fibers come together to constitute larger powerhouses—the
muscles themselves. For example, the muscle that permits you to
contract your forearm consist