With your host… Arnold Schwarzenegger The Muscular System With your host… Arnold Schwarzenegger

? What do muscles do? Muscles move you! Without muscles you couldn't open your mouth, speak, shake hands, walk, talk, or move your food through your digestive system. There would be no smiling, blinking, breathing. Muscles turn energy into motion. (Think of all the things you do that you need your muscles for! It would be impossible for you to do anything without your muscles!)

That’s about the weight of THREE African Elephants! Did you know…? If all 600+ muscles in your body pulled in one direction, you could lift 25 tons!!! That’s about the weight of THREE African Elephants!

Types of Muscles

Smooth muscles Also called involuntary muscles (Your brain and body tell these muscles what to do without you even thinking about it.) Located in your internal organs. Examples: in diaphragm, walls of digestive organs.

Cardiac muscle Found only in the heart. Cardiac muscle is striated, like skeletal muscle.

Skeletal Muscle Also called voluntary muscle. (They only work when you specifically tell them what to do). These are the muscles that we can see, feel, and control. Make up 50% of your body weight. Examples: bicep, tricep.

What's the job of skeletal muscle? Body movement Posture Body heat Communication

Major Skeletal Muscles

How do you move? You move because pairs of muscles work together. When one muscle of a pair contracts, the other relaxes. Flexor - muscle that flexes, or bends a joint Extensor - muscle that extends, or straightens a joint Muscles always pull!



Other muscle knowledge… Over time, muscles can become larger or smaller, depending on whether or not they are used. Blood carries energy-rich molecules to the muscles so they can do their work.

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