2. The Muscular System (1:51) Click here to launch video Click here to download print activity

3. The muscular system enables the limbs and other parts of the body to move.

4. What Muscles Do The muscular system allows for voluntary and involuntary movements. Your muscular system allows you to move.

5. What Muscles Do Involuntary muscle movements help you breathe, make your heart beat, and move food through your digestive system.

6. What Muscles Do Skeletal muscles work in pairs to produce movement.

7. How Muscles Work Muscles consist of long, fibrous cells that can shorten and stretch to make muscles move. Major muscles in the body are made up of hundreds of bundles of muscle fibers.

8. How Muscles Work When bundles of muscles are stimulated by nerve impulses, or signals, they contract, or shorten. When they relax, the bundles extend, or stretch.

9. Types of Muscles Three Types of Muscle Tissue Smooth Muscle Skeletal Muscle Cardiac Muscle

10. Types of Muscles Smooth muscles are involuntary muscles. Smooth muscles Muscles that act on the lining of the body’s passageways and hollow internal organs

11. Types of Muscles Most of your muscle tissue is skeletal, and almost all skeletal muscles are under voluntary control. Skeletal muscles Muscles attached to bone that cause body movements

12. Types of Muscles When you bend and straighten your arm at the elbow, the biceps is the flexor. Flexor The muscle that closes a joint

13. Types of Muscles When you bend and straighten your arm at the elbow, the triceps is the extensor. Extensor The muscle that opens a joint

14. Types of Muscles Cardiac muscle is involuntary and is responsible for the contraction of your heart. Your heart beats 100,000 times each day. Cardiac muscle A type of striated muscle that forms the wall of the heart

15. Caring for Your Muscles Eating a healthy diet and getting regular exercise will help you care for your muscular system. Muscle tone is the natural tension in the fibers of a muscle.

16. Caring for Your Muscles Get regular exercise. Eat high protein foods to build muscle. Practice good posture to strengthen back muscles. Use proper equipment and wear appropriate clothing to protect muscles during any physical activity. Warm up properly and stretch before exercising, and cool down after exercising to prevent injury.

17. Caring for Your Muscles Prepare your muscles by stretching before beginning a workout.

18. Understanding Muscular Problems Caring for the muscular system can help prevent health problems and injuries. Recovery from muscle injuries varies according to the type and severity of the injury or disease.

19. Understanding Muscular Problems Bruises are areas of discolored skin that appear after an injury that causes the blood vessels beneath the skin to rupture and leak. Large bruises can be treated with an ice pack to reduce initial swelling.

20. Understanding Muscular Problems Muscle strains result when muscles are stretched or partially torn from overexertion. Apply ice to strains to reduce swelling, and rest the affected area.

21. Understanding Muscular Problems Tendinitis can be caused by injury, overuse, or natural aging. Tendinitis The inflammation of a tendon

22. Understanding Muscular Problems Hernias commonly occur in the abdomen from straining to lift a heavy object. Surgery can usually repair hernias. Hernia An organ or tissue protrudes through an area of weak muscle

23. Understanding Muscular Problems Muscular dystrophy is an inherited disorder in which skeletal muscle fibers are progressively destroyed. There is no cure, but with early detection, muscle weakness can be delayed through exercise programs.