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Chapter 9 Outline

Chapter 9 Outline - Vandan Desai BIOL 251Anatomy Physiology...

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Vandan Desai BIOL 251—Anatomy & Physiology I 1 Chapter 9—Muscles and Muscles Tissue I. Overview of Muscle Tissues (pp. 276–277; Table 9.3) A. Types of Muscle Tissue (p. 276; Table 9.3) 1. Skeletal muscle is associated with the bony skeleton, and consists of large cells that bear striations and are controlled voluntarily. 2. Cardiac muscle occurs only in the heart, and consists of small cells that are striated and under involuntary control. 3. Smooth muscle is found in the walls of hollow organs, and consists of small elongated cells that are not striated and are under involuntary control. B. Special Characteristics of Muscle Tissue (p. 276) 1. Excitability, or irritability, is the ability to receive and respond to a stimulus. 2. Contractility is the ability to contract forcibly when stimulated. 3. Extensibility is the ability to be stretched. 4. Elasticity is the ability to resume the cells’ original length once stretched. C. Muscle Functions (pp. 276–277; Table 9.3) 1. Muscles produce movement by acting on the bones of the skeleton, pumping blood, or propelling substances throughout hollow organ systems. 2. Muscles aid in maintaining posture by adjusting the position of the body with respect to gravity. 3. Muscles stabilize joints by exerting tension around the joint. 4. Muscles generate heat as a function of their cellular metabolic processes. II. Skeletal Muscle (pp. 277–305; Figs. 9.1–9.25; Tables 9.1–9.3) A. Gross Anatomy of Skeletal Muscle (pp. 277–278; Fig. 9.2; Tables 9.1, 9.3) 1. Each muscle has a nerve and blood supply that allows neural control and ensures adequate nutrient delivery and waste removal. 2. Connective tissue sheaths are found at various structural levels of each muscle: endomysium surrounds each muscle fiber, perimysium surrounds groups of muscle fibers, and epimysium surrounds whole muscles. 3. Attachments span joints and cause movement to occur from the movable bone (the muscle’s insertion) toward the less movable bone (the muscle’s origin). 4. Muscle attachments may be direct or indirect. B. Microscopic Anatomy of a Skeletal Muscle Fiber (pp. 278–284; Figs. 9.2–9.6; Tables 9.1, 9.3) 1. Skeletal muscle fibers are long cylindrical cells with multiple nuclei beneath the sarcolemma. 2. Myofibrils account for roughly 80% of cellular volume, and contain the contractile elements of the muscle cell. 3. Striations are due to a repeating series of dark A bands and light I bands. 4. Myofilaments make up the myofibrils, and consist of thick and thin filaments.
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Vandan Desai BIOL 251—Anatomy & Physiology I 2 5. Ultrastructure and Molecular Composition of the Myofilaments a. There are two types of myofilaments in muscle cells: thick filaments composed of bundles of myosin, and thin filaments composed of strands of actin.
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