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Chapter 10 Skeletal Muscle Tissue I. Overview of Muscle Tissue (p. 239) A. In all its forms, muscle tissue makes up nearly half the body’s mass. B. Functions of muscle tissue include movement, posture maintenance, joint stabilization, and generation of body heat. C. Special functional characteristics separate muscle tissue from other tissues; special properties include contractility, excitability, extensibility, and elasticity. D. The three types of muscle tissue are skeletal, cardiac, and smooth; a cell in skeletal and smooth muscle tissue is called a fiber. II. Skeletal Muscle (pp. 239–251, Figs. 10.1–10.11, and Table 10.1) A. Basic features of skeletal muscle include connective tissue sheaths, fascicles, nerves, blood vessels, and attachment to bones. B. Every skeletal muscle is an organ. C. The muscle ends of attachment are termed the origin and insertion; attachments also are direct (fleshy) or indirect. D. Microscopic and functional anatomy of skeletal muscle tissue examines the structure and function of the skeletal muscle fiber. E. A skeletal muscle fiber is a single, very long cylindrical, multinucleate cell characterized by the presence of myofibrils and sarcomeres; these striated cells are controlled voluntarily. F. The mechanism of contraction is explained by the sliding filament theory. G. Muscle tissue can be stretched by the contraction of an opposing muscle. This is called muscle extension and should not be confused with muscle elasticity. H. Muscles attach to the skeleton at a near optimal length for generating the strongest pulling forces. I. Sarcomeres resist overextension due to the influence of titin and other myofibril proteins. J. Skeletal muscle contraction is regulated by two sets of intracellular tubules; sarcoplasmic reticulum is smooth endoplasmic reticulum that stores calcium ions and T tubules are deep invaginations of the sarcolemma. K. Nerve cells that innervate skeletal muscles are motor neurons. L. The neuromuscular junction is the point where a nerve ending and muscle fiber meet. M. A motor unit consists of a motor neuron and all the muscle fibers it innervates. N. The three types of skeletal muscle fibers are slow oxidative fibers, fast glycolytic fibers, and fast oxidative fibers. III. Disorders of Muscle Tissue (p. 251) A. Examples of disorders of skeletal muscle tissue are muscular dystrophy, myofascial pain syndrome, and fibromyalgia. SUPPLEMENTAL STUDENT MATERIALS to Human Anatomy, Fifth Edition Chapter 10: Skeletal Muscle Tissue To the Student Chapter 10 provides the opportunity to learn about muscle tissue. One of the four major types of body tissues, muscle tissue constitutes nearly half of the body’s mass. Because of contraction of muscle tissues, you move in countless ways, blood moves through vessels, air enters and exits lungs, and food moves along the digestive tract. Chapter 10 builds the foundation for your future study of myology, the skeletal muscles of your body, the heart and circulation, and the many internal organs that have muscle tissue in their walls. Step 1: Characterize muscle tissue. - Explain why a muscle cell is a muscle cell. - List and describe four functional properties distinguishing muscle tissue from other tissues. - Using the following characteristics, design a chart for the comparison of skeletal, cardiac, and smooth muscle tissue: • Location in body • Cell shape • Cell appearance • Type of contraction • Connective tissue components • Presence of striations • Presence of gap junctions • Presence of neuromuscular junctions Step 2: Understand the basic features of a skeletal muscle. - List the levels of organization in a muscle going from a whole muscle to a myofilament. - List and explain the connective tissue components of skeletal muscle. - Explain the vascular nature of skeletal muscle. - Describe innervation of skeletal muscle. - Distinguish between the origin and insertion of muscle in several ways. - Distinguish between a tendon and aponeurosis. Step 3: Understand microscopic and functional anatomy of skeletal muscle. - Describe the shape of a skeletal muscle cell, and explain why it is multinucleated. - Define a myofibril. - Draw a myofibril and show the sarcomeres and myofilaments responsible for striations. - Define a sarcomere. - Draw a sarcomere and label the following functional units: actin, myosin, titin, Z disc, and M line. - Explain the sliding filament theory of muscle contraction. - Explain how myofilaments determine the striation pattern in skeletal and cardiac muscle fibers. - Describe the functional feature of elasticity of skeletal muscle and how overextension is prevented. - Describe the role of the sarcoplasmic reticulum and T tubules in the skeletal muscle fiber. - Describe the innervation of skeletal muscle fibers. - Describe the components of a motor unit. - Define axon terminals and synaptic cleft. - Distinguish between three types of skeletal muscle fibers: slow oxidative fibers, fast glycolytic fibers, and fast oxidative fibers. Step 4: Explain muscle tissue throughout life. - Describe the embryonic origin of muscle tissue. - Indicate the degree of regeneration for each type of muscle tissue. - Explain why men have more muscle mass than women. - Compare muscles of old age and young age in several ways.
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