An Amazing Machine
What is the most amazing machine in the world?
Is it the jet plane? Jets are big, powerful machines. The wings of some jumbo jets weigh over 90,000 pounds! Some jets can travel more than 12,000 miles without landing. Huge engines help keep them in the air.
Maybe it's the computer. They are powerful machines, too. Unlike jets, they don't have engines to make them work. They have CPUs. That stands for central processing unit. The first computers were used in business to compute, or figure out lots of numbers. These giant machines took up the space of whole rooms. Only trained people could use them. Today's computers fit on a desk. Even young children can use them to write, draw, and send e-mails to friends.
Maybe you don't think the jet or the computer is the most amazing machine. Maybe you agree with people who think the most amazing machine in the world is the human body.
Like a jet, the human body has an engine. Its engine is the heart. But no one has to turn it on or plug it in. On its own, the heart pumps about 2,000 gallons of blood a day through the body. By the end of the day, that blood has gone about 12,000 miles. A jet needs more than one engine to travel that far!
The body has its own CPU, too. The body's CPU is the brain. Like a computer's CPU, the brain controls all of the body's actions. It does this by sending messages to body parts. It's kind of like e-mail, only faster.
The body is a different kind of machine. It's not built in a factory. It moves on two feet. And it grows! Best of all, it's yours. Take good care of it. Unlike other machines, you can't buy a new one in a store!