1. End Show Slide 1 of 37 Copyright Pearson Prentice Hall 36–2 The Muscular System

2. End Show 36–2 The Muscular System Slide 2 of 37 Copyright Pearson Prentice Hall Types of Muscle Tissue There are three different types of muscle tissue: skeletal smooth cardiac

3. End Show 36–2 The Muscular System Slide 3 of 37 Copyright Pearson Prentice Hall Types of Muscle Tissue Skeletal Muscles attached to bones. voluntary movements. many nuclei. called striated muscles.

4. End Show 36–2 The Muscular System Slide 4 of 37 Copyright Pearson Prentice Hall Types of Muscle Tissue Smooth Muscles involuntary control. spindle-shaped. one nucleus. internal organs and blood vessels.

5. End Show 36–2 The Muscular System Slide 5 of 37 Copyright Pearson Prentice Hall Types of Muscle Tissue Cardiac Muscle only in the heart. striated. one or two nuclei. involuntary

6. End Show 36–2 The Muscular System Slide 6 of 37 Copyright Pearson Prentice Hall Muscle Contraction The fibers in skeletal muscles are composed of myofibrils. Each myofibril is made up of protein filaments. The thick filaments are myosin. The thin filaments are actin.

7. End Show 36–2 The Muscular System Slide 7 of 37 Copyright Pearson Prentice Hall Muscle Contraction Skeletal muscle Bundle of muscle fibers Muscle fiber (cell) Myofibril Z line Sarcomere Myosin Actin

8. End Show 36–2 The Muscular System Slide 8 of 37 Copyright Pearson Prentice Hall Muscle Contraction Sliding filament model of muscle contraction A muscle contracts when the thin filaments in the muscle fiber slide over the thick filaments.

9. End Show Slide 9 of 37 36–2 The Muscular System Copyright Pearson Prentice Hall Muscle Contraction During contraction, actin filaments slide over myosin filaments, decreasing the distance between the Z lines.

10. End Show 36–2 The Muscular System Slide 10 of 37 Copyright Pearson Prentice Hall Muscle Contraction Binding sites Myosin Cross-bridge Actin Movement of Actin Filament

11. End Show 36–2 The Muscular System Slide 11 of 37 Copyright Pearson Prentice Hall Muscle Contraction During muscle contraction, the head of a myosin filament attaches to a binding site on actin, forming a cross-bridge.

12. End Show 36–2 The Muscular System Slide 12 of 37 Copyright Pearson Prentice Hall Muscle Contraction Powered by ATP, the myosin cross-bridge changes shape and pulls the actin filament toward the center of the sarcomere.

13. End Show 36–2 The Muscular System Slide 13 of 37 Copyright Pearson Prentice Hall Muscle Contraction The cross-bridge is broken, the myosin binds to another site on the actin filament, and the cycle begins again.

14. End Show 36–2 The Muscular System Slide 14 of 37 Copyright Pearson Prentice Hall Muscle Contraction When many myosin cross-bridges change shape, the muscle fiber shortens with considerable force. The energy for contraction is supplied by ATP.

15. End Show 36–2 The Muscular System Slide 15 of 37 Copyright Pearson Prentice Hall Control of Muscle Contraction Motor neurons control the contraction of skeletal muscle fibers. A neurotransmitter called acetylcholine causes muscles to contract.

16. End Show 36–2 The Muscular System Slide 16 of 37 Copyright Pearson Prentice Hall How Muscles and Bones Interact Skeletal muscles are joined to bones by tendons. Origin – end of muscle attached to bone with no movement Insertion – end of the muscle attached to bone that moves. Flexor – muscle that flexes or bends a joint. Extensor – muscle that extends or straightens a joint.

17. End Show 36–2 The Muscular System Slide 17 of 37 Copyright Pearson Prentice Hall How Muscles and Bones Interact Opposing Muscles Contract and Relax

18. End Show 36–2 The Muscular System Slide 18 of 37 Copyright Pearson Prentice Hall How Muscles and Bones Interact Opposing Muscles Contract and Relax

19. End Show Slide 19 of 37 Copyright Pearson Prentice Hall 36–2 Skeletal muscles are joined to bones by tough connective tissue called a.ligaments. b.tendons. c.filaments. d.bursae.

20. End Show Slide 20 of 37 Copyright Pearson Prentice Hall 36–2 Muscle cells that are large, have many nuclei, and striations are a.skeletal muscle cells. b.smooth muscle cells. c.cardiac muscle cells. d.involuntary muscle cells.

21. End Show Slide 21 of 37 Copyright Pearson Prentice Hall 36–2 Muscle that is found in the walls of blood vessels and intestines is a.skeletal muscle. b.smooth muscle. c.cardiac muscle. d.striated muscle.

22. End Show Slide 22 of 37 Copyright Pearson Prentice Hall 36–2 The filaments found in skeletal muscle cells are a.actin and myosin b.myosin and myofibrils c.actin and Z lines d.actin and sarcomeres

23. End Show Slide 23 of 37 Copyright Pearson Prentice Hall 36–2 The type of muscle found only in the heart is a.skeletal muscle. b.striated muscle. c.cardiac muscle. d.smooth muscle.