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Muscle Physiology_Week 1_English (1).pptx
- 1. Muscle Physiology Systems inPhysiology 244 Dr Sanjeev Rambharose
- 2. COURSE CONTENT Chapter 8– Muscle Physiology 1. Structure of Skeletal Muscle (Micro anatomy) • Sarcomere • Actin • Myosin • Troponin • Tropomyosin • Titin
- 3. COURSE CONTENT Chapter 8– Muscle Physiology 2. Molecular basis of contraction (Sliding Filament Theory) o Excitation o Contraction o Coupling 3. The Neuro-muscular Junction (Chapter 7)
- 4. COURSE CONTENT Chapter 8– Muscle Physiology 4. Skeletal Muscle Mechanics (The Muscle Twitch and Factors that may influence it) o Frequency of impulses (tetanus) o Number of motor units o Exhaustion o Temperature o Length of muscle fibers before contraction o Load o Types of contraction
- 5. COURSE CONTENT Chapter 8– Muscle Physiology 5. Muscle Metabolism 6. Types of Muscle Fibres 7. Adaptations of Muscle Fibres with Exercise
- 6. Muscle Tissue Types •Smooth Muscle • Cardiac Muscle • Skeletal muscle, also known as striated muscle or voluntary muscle. • 30 – 40 % body weight
- 7. Muscle Tissue Types •Short video that explains muscle tissue types. o https://www.youtube.com/watch?v=eShBZ3-RxHA
- 8. Skeletal Muscle • Cellsknown as muscle fibres • Multiple nuclei per cell (fiber) • Attached to bones – Facilitates movement
- 9. Skeletal Muscle Fiber •Myofibril • Myofibrils are specialized contractile elements • Contain highly organized microfilaments o Thick and thin filaments
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- 11. The functional unitor sarcomere • A myofibril displays alternating dark bands (the A bands) and light bands (the I bands) • A band – stacked set of thick filaments along with the portions of the thin filaments • Middle of A band – H zone • M line – supporting proteins • I band – Thin filaments that don’t project into the A band • Z line • Sarcomere
- 12. The functional unitor sarcomere • Growth – increase in length by adding new sarcomeres • Titin o Scaffolding o Elastic spring o Signal transduction
- 15. Myosin • A myosinmolecule is a protein shaped somewhat like a golf club • Myosin can bend at hinge points in two locations • Heads form the cross bridges • Actin binding site • Myosin ATPase site
- 16. Actin • Thin filamentscontain 3 proteins: • Actin • Tropomyosin • Troponin • Tropomyosin – covers the actin sites that bind with the cross bridges. • Troponin - stabilizes tropomyosin in its blocking position over actin’s cross-bridge binding sites The thin or actin filaments The regulatory prot.troponin & tropomyosin
- 17. Role of Calciumin turning on cross bridges
- 18. Check Your Understanding 1.Compare the relationship among myofibrils, muscle fibers, and a whole muscle. 2. Illustrate the relative positions of the cytoskeletal structures that make up a sarcomere. 3. Describe how actin, tropomyosin, and troponin are organized in a relaxed muscle fiber.
- 19. Molecular Basis ofSkeletal Muscle Contraction • How does cross-bridge interaction between actin and myosin bring about muscle contraction? • How does a muscle action potential trigger this contractile process? • What is the source of the Calcium that permit crossbridge binding?
- 20. Sliding Filament Theory •Thin filaments on each side of a sarcomere slide inward over the stationary thick filaments toward the A band’s center during contraction. • Thin filaments pull the Z lines closer together, so in effect the sarcomere shortens. • All sarcomeres throughout the length of the Muscle fiber shorten simultaneously – entire muscle fiber shortens
- 22. Power Stroke • Myosincross bridges “walk” along an actin filament to pull it inward relative to the stationary thick filament. • When actin and myosin bind, myosin’s head tilts inward • Bending at this neck hinge point creates a “stroking” motion • Thin filament is pulled toward the center of the sarcomere • Power stroke of a cross bridge
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- 26. Skeletal Muscle Contraction •Please refer to Memo1 - Skeletal Muscle Contraction for more details in English and Afrikaans.