The musculoskeletal System

 

Did you know you have more than 600 muscles in your body? They do everything from pumping blood throughout your body to helping you lift your heavy backpack. 

You control some of your muscles, while others — like your heart — do their jobs without you thinking about them at all.

Muscles are all made of the same material, a type of elastic tissue (sort of like the material in a rubber band). Thousands, or even tens of thousands, of small fibers make up each muscle.

You have three different types of muscles in your body: smooth muscle, cardiac muscle, and skeletal muscle.