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

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Presentation on theme: "Essentials of Human Anatomy & Physiology Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Seventh Edition Elaine N. Marieb Chapter."— Presentation transcript:

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)  Muscles are responsible for all types of body movement  Three basic muscle types are found in the body  Skeletal muscle  Cardiac muscle  Smooth muscle

3 Characteristics of Muscles Slide 6.2 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Muscle cells are elongated (muscle cell = muscle fiber)  Contraction of muscles is due to the movement of microfilaments  All muscles share some terminology  Prefix myo refers to muscle  Prefix mys refers to muscle  Prefix sarco refers to flesh

4 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

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

6 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

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

8 Connective Tissue Wrappings of Skeletal Muscle Slide 6.4a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Endomysium – around single muscle fiber  Perimysium – surrounds multiple fibers Figure 6.1

9 Connective Tissue Wrappings of Skeletal Muscle Slide 6.4b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Fascicle - bundle of fibers  Epimysium – covers the entire skeletal muscle Figure 6.1

10 Skeletal Muscle Attachments Slide 6.5 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Epimysium blends into a connective tissue attachment  Tendon – cord-like structure  Aponeuroses – sheet-like structure  Sites of muscle attachment  Bones  Cartilages  Connective tissue coverings

11 Smooth muscle Lines walls of hollow organs Ex stomach, bladder Found in two layers Layers alternately contract Function: –Propels substances along a tract

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

13 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

14 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

15 Cardiac Muscle Activity Intercalated disks closely coordinate activity Own pacemaker controls contraction Can be stimulated by the nervous system Muscle contracts  chambers become smaller forcing blood into arteries

16 Microscopic Anatomy of Skeletal Muscle Slide 6.9a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Cells are multinucleate  Nuclei are just beneath the sarcolemma Figure 6.3a

17 Microscopic Anatomy of Skeletal Muscle Slide 6.9b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Sarcolemma – specialized plasma membrane  Sarcoplasmic reticulum – specialized smooth endoplasmic reticulum Figure 6.3a

18 Microscopic Anatomy of Skeletal Muscle Slide 6.10a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Myofibril  Bundles of myofilaments  Myofilaments are aligned to give distrinct bands  I band = light band  A band = dark band Figure 6.3b

19 Microscopic Anatomy of Skeletal Muscle Slide 6.10b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Sarcomere  Contractile unit of a muscle fiber Figure 6.3b

20 Microscopic Anatomy of Skeletal Muscle Slide 6.11a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Organization of the sarcomere  Thick filaments = myosin filaments  Composed of the protein myosin  Has ATPase enzymes Figure 6.3c

21 Microscopic Anatomy of Skeletal Muscle Slide 6.11b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Organization of the sarcomere  Thin filaments = actin filaments  Composed of the protein actin Figure 6.3c

22 Microscopic Anatomy of Skeletal Muscle Slide 6.12a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Myosin filaments have heads (extensions, or cross bridges)  Myosin and actin overlap somewhat Figure 6.3d

23 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

24 Nerve Stimulus to Muscles Slide 6.14 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Skeletal muscles must be stimulated by a nerve to contract (motor neruron)  Motor unit  One neuron  Muscle cells stimulated by that neuron Figure 6.4a

25 Nerve Stimulus to Muscles Slide 6.15a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Neuromuscular junctions – association site of nerve and muscle Figure 6.5b

26 Nerve Stimulus to Muscles Slide 6.15b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Synaptic cleft – gap between nerve and muscle  Nerve and muscle do not make contact  Area between nerve and muscle is filled with interstitial fluid Figure 6.5b

27 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 + )

28 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

29 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

30 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

31 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

32 Muscles and Body Movements Slide 6.30a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Movement is attained due to a muscle moving an attached bone Figure 6.12

33 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

34 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

35 Types of Ordinary Body Movements Slide 6.32 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Flexion – decreases angle of joint and brings two bones closer together  Extension- opposite of flexion  Rotation- movement of a bone in longitudinal axis, shaking head “no”  Abduction/Adduction (see slides)  Circumduction (see slides)

36 Body Movements Slide 6.33 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 6.13

37 Left: Abduction – moving the leg away from the midline Above – Adduction- moving toward the midline Right: Circumduction: cone- shaped movement, proximal end doesn’t move, while distal end moves in a circle.

38 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


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