Chapter 10

1. Chapter 10 The Muscular System and Homeostasis

2. Chapter 10 The Muscular System and Homeostasis 10.1 Movement and Muscle Tissue 10.2 Muscles, Health, and Homeostasis

3. Chapter 10 The Muscular System and Homeostasis In this chapter, you will learn: • There are three types of muscle tissue: skeletal muscle, smooth muscle, and cardiac muscle. • Skeletal muscle produces body movement, maintains body temperature, and provides support for the body. • Muscle fibres are filled with myofibrils that house thin (actin) and thick (myosin) contractile protein myofilaments. • Actin and myosin slide past each other during a muscle contraction. • Creatine phosphate, fermentation, and aerobic cellular respiration provide energy for muscle contractions. • Three types of skeletal muscle—slow-twitch, fast-twitch, and an intermediate type—are found in different parts of the body. • Muscles atrophy with inadequate stimulation and can hypertrophy with appropriate repeated stimulation. • The muscular system works with other body systems to maintain homeostasis.

4. 10.1 Movement and Muscle Tissue In this section, you will: • observe and compare the three types of muscle tissue • describe, in general, the action of actin and myosin in muscle contraction and heat production • identify the sources of energy for muscle contraction

5. Muscle Cells

6. Muscle Function • Skeletal muscle supports the body. • Skeletal muscle makes the bones move. • Skeletal muscle helps to maintain a constant body temperature. • Skeletal muscle helps to protect the internal organs and stabilize the joints.

7. Muscle Fibres

8. Components of Skeletal Muscle Fibres

9. The Movement of Actin and Myosin

10. Sliding Filament Model

11. Calcium Controls Muscle Contractions

12. animations • http://www.youtube.com/watch?v=Y1tx8U8c670 • http://media.pearsoncmg.com/bc/bc_campbell_biology_7/media/interactivemedia/activities/load.html?49&C • http://www.mcgrawhill.ca/school/applets/abbio/quiz/ch10/myofilament_contraction.swf • http://www.mcgrawhill.ca/school/applets/abbio/quiz/ch10/sarcomere_contraction.swf • http://media.pearsoncmg.com/bc/bc_campbell_biology_7/media/interactivemedia/activities/load.html?49&D

13. Energy for Muscle Contraction ATP required for contraction and is generated by THREE mechanisms.

14. Creatine phosphate builds up and is stored in resting muscle (purple box). For the muscle to contract (green area), it needs to acquire ATP. (A) When the muscle starts contracting, it breaks down stored creatine phosphate. This generates some ATP that is used immediately. (B) To continue contracting, the muscle carries out aerobic cellular respiration as long as oxygen is available. When the oxygen has been used up, the muscle can carry out fermentation for a limited period of time. Fermentation results in only a small amount of ATP compared with the amount produced by aerobic cellular respiration, and lactate builds up. Once the muscle resumes resting (purple box), creatine phosphate builds up again.

15. #1 Creatine Phosphate Breakdown Creatine phosphate quickly regenerates ATP by directly donating a phosphate (good for about 15 seconds, first ATP regeneration mechanism to kick in under anaerobic conditions)

16. #2 Cellular Respiration ATP is made in mitochondria by aerobic means - requires oxygen. Pyruvicacid is transported into mitochondria and oxidized to carbon dioxide and water.

17. “#3 Fermentation" (glycolysis) Anaerobic production of ATP by glycolysis occurs during strenuous exercise after CP stores are exhausted. Very inefficient, good for only 1-2 minutes before muscle fatigue occurs. The end product of glycolysis, pyruvic acid, is converted to lactic acid if it isn't metabolized by cellular respiration fast enough to meet ATP needs of the muscle. Lactic acid builds up, the pH drops, muscles fatigue and ache.

18. Oxygen Debt • Lactic acid is transported to the liver where it is converted back to pyruvic acid, which is then metabolized by cellular respiration, which of course requires oxygen. • The amount of oxygen required to finish metabolism of lactic acid is the oxygen debt - that’s the wind-sucking you do after going anaerobic.

19. 10.2 Muscles, Health, and Homeostasis In this section, you will: • explain how the skeletal muscles of the motor system support other body systems to maintain homeostasis • identify conditions that impair the healthy functioning of muscles and technologies that are used to treat or prevent these conditions • describe the benefits of exercise for maintaining the healthy structure and functioning of muscles

20. Muscular Atrophy, Sprains and Strains A strain is an injury to either a muscle or a tendon, the tissue that connects muscles to bones. Depending on the severity of the injury, a strain may be a simple overstretch of the muscle or tendon, or it can result in a partial or complete tear. A sprain is an injury to a ligament, the tough, fibrous tissue that connects bones to other bone. Ligament injuries involve a stretching or a tearing of this tissue.

21. Common Disorders & Ailments of Skeletal Muscles

22. Myograms These graphs show the force of muscle contraction with time. (A) A simple muscle twitch has three periods: latent, contraction, and relaxation. (B) When a muscle is not allowed to relax completely between stimuli, the contraction gradually increases in intensity until it reaches a maximum, which is sustained until the muscle fatigues.

23. Types muscle fibres

24. Skeletal muscles have different proportions of fast-twitch and slow-twitch fibres. Thus, the force andresponse times of their contractions differ.

26. Chapter 10 Review • What body systems do muscles support? • How do muscles support these systems? • Explain the difference in muscle composition between a person who is not active versus someone who is very active? • Describe two different types of muscle injuries. Recommend appropriate treatments for each. • Explain how muscles change with strength training? With endurance training? With inactivity?

27. Concept Organizer

28. Chapter 10 Summary • All muscles do their work by contracting (shortening). Relaxation is the passive state of a muscle. There are three types of muscle cells: skeletal, smooth, and cardiac. • Skeletal muscle cells are attached to the bones of the skeleton, have many nuclei, are striated and tubular, and contract voluntarily. • Smooth muscle cells are found in the walls of internal organs, have one nucleus, are not striated, and contract involuntarily. • Cardiac muscle cells form the walls of the heart; have one nucleus, are striated, tubular, and branched; and contract involuntarily. • The fact that skeletal muscles can only either contract or relax means they can pull but not push. Therefore, they must work in pairs to move any part of the body—a relaxed muscle is only lengthened when the opposing muscle contracts to stretch it. Skeletal muscle contractions are explained by the sliding filament model.

29. Chapter 10 Summary • Skeletal muscle produces heat as well as movement and also supports and pads the body. Each muscle is made up of clusters of bundles of muscle fibres, which enclose bundles of myofibrils containing thin myofilaments of actin and thick myofilaments of myosin. Blood vessels supply nutrients and oxygen to the fibre bundles and remove wastes. The oxygen fuels the cellular respiration that supplies most of the energy muscles use. • Nerves trigger and control muscle contractions, which last for only a fraction of second in each muscle fibre. It is the wave of successive contractions, or twitches, that result in a muscle contraction. Skeletal muscles have both slow and fast-twitch fibres that are good for either endurance (slow-twitch) or intense (fast-twitch) activities. Using the skeletal muscles is the only way to maintain and build their function.

30. Videos • http://www.youtube.com/watch?v=jqy0i1KXUO4 13 minutes Crash course • http://www.youtube.com/watch?v=BXOTb4ZxKDI Extraordinary Humans: Muscles (45 min) • http://www.youtube.com/watch?v=EKWaJ_7PPXE Science of steroids National geographic (45 min)