Learning Outcomes 10-1 Identify the common properties of muscle tissues and the primary functions of skeletal muscle. 10-2 Describe the organization of muscle at the tissue level. 10-3 Describe the characteristics of skeletal muscle fibers, and identify the components of a sarcomere. 10-4 Identify the components of the neuromuscular junction, and summarize the events involved in the neural control of skeletal muscle contraction and relaxation. 10-5 Describe the mechanism responsible for the different amounts of tension produced in a muscle fiber.

Learning Outcomes 10-6 Compare the different types of skeletal muscle contraction. 10-7 Describe the mechanisms by which muscle fibers obtain the energy to power contractions. 10-8 Relate the types of muscle fibers to muscle performance, discuss muscle hypertrophy, atrophy, and aging, and describe how physical conditioning affects muscle tissue. 10-9 Identify the structural and functional differences between skeletal muscle fibers and cardiac muscle cells. 10-10 Identify the structural and functional differences between skeletal muscle fibers and smooth muscle cells, and discuss the roles of smooth muscle tissue in systems throughout the body.

Figure 10.1 The Organization of Skeletal Muscle Please review Figure 10.1; part a, part b and part c. Also review the unlabeled diagram in the bottom lower left corner.

Figure 10–1a The Organization of Skeletal Muscles. Skeletal Muscle (organ) Epimysium Perimysium Endomysium Nerve Muscle fascicle Muscle fibers Blood vessels Bone Epimysium Blood vessels and nerves Endomysium Tendon Perimysium

Figure 10–1b The Organization of Skeletal Muscles. Muscle Fascicle (bundle of fibers) Perimysium Muscle fiber Bone Epimysium Blood vessels and nerves Endomysium Endomysium Tendon Perimysium

Figure 10–1c The Organization of Skeletal Muscles. Muscle Fiber (cell) Bone Epimysium Capillary Myofibril Endomysium Sarcoplasm Blood vessels and nerves Mitochondrion Myosatellite cell Sarcolemma Nucleus Endomysium Axon of neuron Tendon Perimysium

Figure 10.2 The Formation of a Multinucleate Skeletal Muscle Fiber Please review Figure 10.2; part b. Pay attention to the individual components of the muscle fiber

Figure 10–2a The Formation of a Multinucleate Skeletal Muscle Fiber. Muscle fibers develop through the fusion of embryonic cells called myoblasts. Myoblasts a A muscle fiber forms by the fusion of myoblasts. Myosatellite cell Nuclei Immature muscle fiber Myosatellite cell Up to 30 cm in length Mature muscle fiber

Figure 10–2b The Formation of a Multinucleate Skeletal Muscle Fiber. Sarcolemma Striations Nuclei Myofibrils Mitochondria b A diagrammatic view and a micrograph of one muscle fiber.

Figure 10.3 The Structure and Internal Organization of a Skeletal Muscle Fiber Please review Figure 10.3 Review the components of the skeletal muscle fiber.

Myofibril Striations Sarcolemma Nuclei Muscle fiber Sarcoplasm Figure 10–3 The Structure and Internal Organization of a Skeletal Muscle Fiber (Part 1 of 4). Myofibril Striations Sarcolemma Nuclei Muscle fiber Sarcoplasm

Thin filament Thick filament Sarcoplasmic reticulum Figure 10–3 The Structure and Internal Organization of a Skeletal Muscle Fiber (Part 2 of 4). Mitochondria Terminal cisterna Sarcolemma Sarcolemma Sarcoplasm Myofibril Myofibrils Thin filament Thick filament Sarcoplasmic reticulum Triad T tubules

Mitochondria Sarcolemma Myofibril Thin filament Thick filament Figure 10–3 The Structure and Internal Organization of a Skeletal Muscle Fiber (Part 3 of 4). Mitochondria Sarcolemma Myofibril Thin filament Thick filament

Sarcoplasmic reticulum Figure 10–3 The Structure and Internal Organization of a Skeletal Muscle Fiber (Part 4 of 4). Terminal cisterna Sarcolemma Sarcoplasm Myofibrils Triad Sarcoplasmic reticulum T tubules

Figure 10.4 Sarcomere Structure, Longitudinal Views Please review Figure 10.4; part a. Pay attention to the banding patterns in the sarcomere. IF you understand what filaments are present and where they are located it will make understanding the pattern quite a bit easier.

Figure 10–4a Sarcomere Structure, Longitudinal Views. I band A band H band Z line Titin Zone of overlap M line Thin filament Thick filament Sarcomere a I bands have only thin filaments. A bands have both thin and thick filaments. H bands have thick filaments and bisect A bands. M lines are the middle of H bands. Z lines bisect the I bands.

Figure 10–4b Sarcomere Structure, Longitudinal Views. I band A band H band Z line Myofibril TEM × 64,000 Z line Zone of overlap M line Sarcomere b A corresponding longitudinal section of a sarcomere in a myofibril from a muscle fiber in the gastrocnemius (calf) muscle of the leg

Figure 10.5 Sarcomere Structure, Superficial and Cross Sectional Views Please review Figure 10.5. Pay attention to the myofilaments present in the sarcomere. IF you understand what filaments are present and where they are located it will make understanding the pattern quite a bit easier.

a A superficial view of a sarcomere Sarcomere Thick filament Myofibril Figure 10–5a Sarcomere Structure, Superficial and Cross-Sectional Views. Sarcomere Thick filament Myofibril Thin filament a A superficial view of a sarcomere

b Cross-sectional views of different regions of a sarcomere Figure 10–5b Sarcomere Structure, Superficial and Cross-Sectional Views. Thin filaments Titin filament Thick filaments Actinin filaments Attachment of titin Z line I band M line H band Zone of overlap b Cross-sectional views of different regions of a sarcomere

Figure 10.6 Levels of Functional Organization in a Skeletal Muscle Please review Figure 10.5. This figure outlines the organization of the components found in skeletal muscle. It reviews Figures 10.1 through 10.5. Can you explain how muscle is organized from the epimysium all the way down to the sarcomere?

Figure 10–6 Levels of Functional Organization in a Skeletal Muscle. Surrounded by: Epimysium Myofibril Surrounded by: Sarcoplasmic reticulum Contains: Muscle fascicles Consists of: Sarcomeres (Z line to Z line) Sarcomere I band A band Contains: Thick filaments Muscle Fascicle Surrounded by: Perimysium Thin filaments Contains: Muscle fibers Titin Z line M line Z line H band Muscle Fiber Surrounded by: Endomysium Contains: Myofibrils

Skeletal Muscle Surrounded by: Epimysium Contains: Muscle fascicles Figure 10–6 Levels of Functional Organization in a Skeletal Muscle (Part 1 of 5). Skeletal Muscle Surrounded by: Epimysium Contains: Muscle fascicles

Muscle Fascicle Surrounded by: Perimysium Contains: Muscle fibers Figure 10–6 Levels of Functional Organization in a Skeletal Muscle (Part 2 of 5). Muscle Fascicle Surrounded by: Perimysium Contains: Muscle fibers

Muscle Fiber Surrounded by: Endomysium Contains: Myofibrils Figure 10–6 Levels of Functional Organization in a Skeletal Muscle (Part 3 of 5). Muscle Fiber Surrounded by: Endomysium Contains: Myofibrils

Myofibril Surrounded by: Sarcoplasmic reticulum Consists of: Figure 10–6 Levels of Functional Organization in a Skeletal Muscle (Part 4 of 5). Myofibril Surrounded by: Sarcoplasmic reticulum Consists of: Sarcomeres (Z line to Z line)

Sarcomere I band A band Contains: Thick filaments Thin filaments Titin Figure 10–6 Levels of Functional Organization in a Skeletal Muscle (Part 5 of 5). Sarcomere I band A band Contains: Thick filaments Thin filaments Titin Z line M line Z line H band