Essentials of Human Anatomy Physiology Seventh Edition Elaine

Essentials of Human Anatomy & Physiology Seventh Edition Elaine N. Marieb Chapter 6 The Muscular System Slides 6. 1 – 6. 17 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

The Muscular System · Named for Latin word “mus” meaning little mouse · Dominant tissue in heart and the walls of other hollow organs · Essential function is to shorten or contract · Responsible for all body movement Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 6. 1

The Muscular System · Three basic muscle types are found in the body · Skeletal muscle · Cardiac muscle · Smooth muscle · Differ in cell structure, location in body and how they’re stimulated to contract Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 6. 1

Characteristics of All Muscle Types · Muscle cells are elongated & called fibers · Contraction of muscles is due to the movement of myofilaments · All muscles share some terminology · Prefixes myo & mys refers to muscle · Prefix sarco refers to flesh Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 6. 2

Skeletal Muscle Characteristics · Most are attached by tendons to bones · Cells are cigar shaped & multinucleate · Striated – have visible banding · Largest of the muscles (up to 1 foot) · Voluntary – subject to conscious control · Often react involuntarily or by reflex Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 6. 3

Skeletal Muscle Characteristics · Can contract rapidly & with great force but tires easily · Fibers (cells) are surrounded and bundled by connective tissue · This allows skeletal muscle to exert great force without damaging the muscle fibers Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 6. 3

Connective Tissue Wrappings of Skeletal Muscle · Endomysium – around single muscle fiber · Perimysium – around a fascicle (bundle) of fibers Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 6. 1 Slide 6. 4 a

Connective Tissue Wrappings of Skeletal Muscle · 3 layers of connective tissue: endomysium, perimysium & epimysium · Each layer gets thicker & tougher Figure 6. 1 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 6. 4 b

Skeletal Muscle Attachments · Epimysium blends into a connective tissue attachment, usually a tendon which attaches to a bone · Sites of muscle attachment · Bones (attached by tendon) · Cartilages · Connective tissue coverings of muscles Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 6. 5

Smooth Muscle Characteristics · Has no striations · Spindle-shaped cells · Single nucleus · Involuntary – no conscious control · Found mainly in the walls of hollow organs Figure 6. 2 a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 6. 6

Smooth Muscle Characteristics · Arranged in sheets or layers – one runs circular or around & the other runs up and down · 2 layers take turns contracting & relaxing to change shape of organ and move food or waste through the digestive system, etc · A slow steady contraction that goes on almost continuously Figure 6. 2 a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 6. 6

Cardiac Muscle Characteristics · Has striations · Usually has a single nucleus · Involuntary · Found only in the heart · Joined to another muscle cell at an intercalated disc Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 6. 2 b Slide 6. 7

Cardiac Muscle Characteristics · Muscle is arranged in spirals or figure 8 s · This causes the chambers to get smaller & squeeze the blood out when it contracts · Contracts at a steady rate controlled by the heart’s pacemaker – nervous system can speed it up Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 6. 2 b Slide 6. 7