1. Essentials of Human Anatomy & Physiology Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Seventh Edition Elaine N. Marieb Chapter 6 The Muscular System

2. The Muscular System Slide 6.1 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Essential function is contraction (shorten)  Three basic muscle types are found in the body  Skeletal muscle  Cardiac muscle  Smooth muscle

3. Role of Muscles in the Body Slide 6.8 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Produce movement  Maintain posture  Stabilize joints  Generate heat  Propel Substances

6. Skeletal muscle Functions –Locomotion and breathing –Maintain posture –Heat production Form smooth contours of body Vary in shape (spindle, fan or circle shape)

7. Skeletal Muscle Characteristics Slide 6.3 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Striated – have visible banding  Cells are multinucleate  Voluntary – subject to conscious control  Attached to bones  Slow to fast contraction

8. Skeletal Muscle Activity Contract rapidly but tire easily Can exert much power without ripping Cells are surrounded by connective tissue Adds strength and support

9. Connective Tissue Wrappings of Skeletal Muscle Slide 6.4a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Notice how Skeletal muscle looks like a cross section of fiber optic cable. Figure 6.1

10. Smooth muscle Lines walls of hollow organs Ex: stomach, bladder Two layers Causes Peristalsis Function: –Propels substances along a tract

11. Smooth Muscle Characteristics Slide 6.6 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  No striations  Single nucleus  Involuntary – no conscious control  Found mainly in the walls of hollow organs  Slow contraction Figure 6.2a

12. Cardiac muscle Pumping mass of heart Arranged in spiral or figure 8 shape Heart muscle cell behave as one unit Heart muscle always contracts to it’s full extent

13. Cardiac Muscle Characteristics Slide 6.7 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Striations  Single nucleus  Involuntary  Found only in the heart  Contracts at slow, steady rate

14. Properties of Skeletal Muscle Fibers Slide 6.13 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Irritability – ability to receive and respond to a stimulus  Contractility – ability to shorten when an adequate stimulus is received

15. Transmission of Nerve Impulse to Muscle Slide 6.16a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Neurotransmitter – chemical released by nerve upon arrival of nerve impulse  The neurotransmitter for skeletal muscle is acetylcholine  Neurotransmitter attaches to receptors on the sarcolemma  Sarcolemma becomes permeable to sodium (Na + )

16. Transmission of Nerve Impulse to Muscle Slide 6.16b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Sodium rushing into the cell generates an action potential  Once started, muscle contraction cannot be stopped

17. Contraction of a Skeletal Muscle Slide 6.19 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Muscle fiber contraction is “all or none”  Not all fibers may be stimulated at the same time

18. Contraction of a Skeletal Muscle Slide 6.22 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Muscle force depends upon the number of fibers stimulated  More fibers contracting results in greater muscle tension  Muscles can continue to contract unless they run out of energy

19. 2.Energy for Muscle Contraction a.Initially, muscles use stored ATP for energy i.ATP bonds are broken to release energy ii.Only 4–6 seconds worth of ATP is stored by muscles b.After this initial time, other pathways must be utilized to produce ATP

20. Energy for Muscle Contraction c.Direct phosphorylation of ADP by creatine phosphate (CP) i.Muscle cells store CP i.CP is a high-energy molecule ii.After ATP is depleted, ADP is left iii.CP transfers energy to ADP, to regenerate ATP iv.CP supplies are exhausted in less than 15 seconds

21. Energy for Muscle Contraction Figure 6.10a

22. Energy for Muscle Contraction d.Aerobic respiration i.Glucose is broken down to carbon dioxide and water, releasing energy (ATP) ii.This is a slower reaction that requires continuous oxygen iii.A series of metabolic pathways occur in the mitochondria

23. Energy for Muscle Contraction Figure 6.10b

24. Energy for Muscle Contraction e.Anaerobic glycolysis and lactic acid formation i.Reaction that breaks down glucose without oxygen ii.Glucose is broken down to pyruvic acid to produce some ATP iii.Pyruvic acid is converted to lactic acid f.This reaction is not as efficient, but is fast i.Huge amounts of glucose are needed ii.Lactic acid produces muscle fatigue

25. Energy for Muscle Contraction Figure 6.10c

26. Muscle Fatigue and Oxygen Debt Slide 6.27 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  When a muscle is fatigued, it is unable to contract  The common reason for muscle fatigue is oxygen debt  Oxygen must be “repaid” to tissue to remove oxygen debt  Oxygen is required to get rid of accumulated lactic acid  Increasing acidity (from lactic acid) and lack of ATP causes the muscle to contract less

27. 4.Types of Muscle Contractions a.Isotonic contractions i.Myofilaments are able to slide past each other during contractions ii.The muscle shortens and movement occurs b.Isometric contractions i.Tension in the muscles increases ii.The muscle is unable to shorten or produce movement

28. C.Naming Skeletal Muscles 1.By direction of muscle fibers a.Example : Rectus (straight) 2.By relative size of the muscle a.Example : Maximus (largest) 3.By location of the muscle a.Example : Temporalis (temporal bone) 4.By number of origins a.Example : Triceps (three heads)

29. Naming Skeletal Muscles 5.By location of the muscle’s origin and insertion a.Example : Sterno (on the sternum) 6.By shape of the muscle a.Example : Deltoid (triangular) 7.By action of the muscle a.Example : Flexor and extensor (flexes or extends a bone)

30. Muscles and Body Movements Slide 6.30b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Muscles are attached to at least two points  Origin – attachment to a moveable bone  Insertion – attachment to an immovable bone Figure 6.12

31. Effects of Exercise on Muscle Slide 6.31 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Results of increased muscle use  Increase in muscle size  Increase in muscle strength  Increase in muscle efficiency  Muscle becomes more fatigue resistant

32. Types of Ordinary Body Movements Slide 6.32 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Complete Exercise Lab

33. Disorders relating to the Muscular System Muscular Dystrophy: inherited, muscle enlarge due to increased fat and connective tissue, but fibers degenerate and atrophy Duchenne MD: lacking a protein to maintain the sarcolemma Myasthemia Gravis: progressive weakness due to a shortage of acetylcholine receptors