1. 6th Grade Science Muscular System

2. I. General Numbers = 600 muscles B. Terminology 1. Muscle means “little mouse” C. Amount 1. 50% of body weight D. Groups 1. Involuntary = Not controlled 2. Voluntary = You have to think about

3. E. Types

4. E. Types Cardiac Muscle (Heart) i. Moves blood 2. Smooth Muscle i. Move fluids inside body ii. Slow acting iii. Long lasting

5. 3. Skeletal Muscle i. Voluntary ii. Get tired iii. React quickly iv. Pull on bones (tendon) a. Must work in pairs v. Maintain posture vi. Stabilize joints vii. Generate heat

6. II. Injuries A. Pulled muscle 1. Overworked or overstretched 2. Tendons can also be partially torn B. Cramps Muscle stays contracted

7. III. Diseases A. Muscular Dystrophy – Convert muscle to fat

8. IV. Structure A. Muscle Bundles

9. B. Skeletal Muscle Cell

10. C. Myofibril

11. D. Skeletal Muscle Fibers 1. Actin 2. Myosin

12. V. Mechanism of Contraction

15. VI. Skeletal Muscle Motor Units Figure 10.1a