9 & 11 - 9 Muscles and Muscle Tissue: Part A Three...

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9 Muscles and Muscle Tissue: Part A Three Types of Muscle Tissue 0. Skeletal muscle tissue: 0. Attached to bones and skin 1. Striated 2. Voluntary (i.e., conscious control) 3. Powerful 4. Primary topic of this chapter Three Types of Muscle Tissue 0. Cardiac muscle tissue: 5. Only in the heart 6. Striated 7. Involuntary 8. More details in Chapter 18 Three Types of Muscle Tissue 0. Smooth muscle tissue: 9. In the walls of hollow organs, e.g., stomach, urinary bladder, and airways 10. Not striated 11. Involuntary 12. More details later in this chapter Special Characteristics of Muscle Tissue 0. Excitability (responsiveness or irritability): ability to receive and respond to stimuli 1. Contractility: ability to shorten when stimulated 2. Extensibility: ability to be stretched 3. Elasticity: ability to recoil to resting length Muscle Functions 1. Movement of bones or fluids (e.g., blood) 1. Maintaining posture and body position 1. Stabilizing joints 0. Heat generation (especially skeletal muscle) Skeletal Muscle 4. Each muscle is served by one artery, one nerve, and one or more veins Skeletal Muscle 0. Connective tissue sheaths of skeletal muscle: 0. Epimysium: dense regular connective tissue surrounding entire muscle 1. Perimysium: fibrous connective tissue surrounding fascicles (groups of muscle fibers) 2. Endomysium: fine areolar connective tissue surrounding each muscle fiber
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Skeletal Muscle: Attachments 5. Muscles attach: 13. Directly—epimysium of muscle is fused to the periosteum of bone or perichondrium of cartilage 14. Indirectly—connective tissue wrappings extend beyond the muscle as a ropelike tendon or sheetlike aponeurosis Microscopic Anatomy of a Skeletal Muscle Fiber 6. Cylindrical cell 10 to 100 μ m in diameter, up to 30 cm long 7. Multiple peripheral nuclei 8. Many mitochondria 9. Glycosomes for glycogen storage, myoglobin for O 2 storage 10. Also contain myofibrils, sarcoplasmic reticulum, and T tubules Myofibrils 11. Densely packed, rodlike elements 12. ~80% of cell volume 13. Exhibit striations: perfectly aligned repeating series of dark A bands and light I bands Sarcomere 14. Smallest contractile unit (functional unit) of a muscle fiber 15. The region of a myofibril between two successive Z discs 16. Composed of thick and thin myofilaments made of contractile proteins Features of a Sarcomere 1. Thick filaments: run the entire length of an A band 2. Thin filaments: run the length of the I band and partway into the A band 3. Z disc: coin-shaped sheet of proteins that anchors the thin filaments and connects myofibrils to one another 4. H zone: lighter midregion where filaments do not overlap 5. M line: line of protein myomesin that holds adjacent thick filaments together Ultrastructure of Thick Filament 6. Composed of the protein myosin 3. Myosin tails contain: 4. 2 interwoven, heavy polypeptide chains 5. Myosin heads contain: 6. 2 smaller, light polypeptide chains that act as cross bridges during contraction 7. Binding sites for actin of thin filaments
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This note was uploaded on 03/22/2011 for the course SCIENCE 202 taught by Professor Reza during the Spring '11 term at Massasoit.

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9 & 11 - 9 Muscles and Muscle Tissue: Part A Three...

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