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Muslces

This comprehensive overview explores the classification of muscles, detailing the roles of agonists, antagonists, synergists, and fixators. It also discusses the criteria for naming muscles based on direction, size, location, and action. The structure of skeletal muscles is outlined, covering fascia, epimysium, perimysium, and endomysium, along with the composition of muscle fibers and myofibrils. The document explains muscle contraction mechanisms, including the roles of acetylcholine and calcium ions, and introduces concepts of energy production through anaerobic and aerobic respiration, as well as addressing muscle fatigue.

zephania-estrada
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Muslces

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Presentation Transcript

  1. Muslces Group 4

  2. Classification • Agonist: prime mover • Antagonist: reverses agonist • Synergist: prevents rotation • Fixator: stabilizes the origin of the prime mover

  3. Naming (LADSNOR!) • Direction of the muscle fibers • Ex) transverse, rectus, oblique • Relative size of muscles • Ex) major, minor • Location • Number and location of origin • Shape • Action of the muscle • Ex) extensor, flexor

  4. Origin and Insertion • Origin: immovable end • Insertion: movable end

  5. Characteristics • Muscle cells are elongated • Contractions are due to the movement of microfilaments

  6. Structure (skeletal muscle)

  7. Structure (cont.) • From outermost to innermost • Muscle>Fascicles>Muscle fibers>Myofibril>Thick and thin filaments • Fascia>Epimysium>Perimysium>Endomysium

  8. Tissue layers of a skeletal muscle • Fascia: covering the whole muscle • Epimysium: lies beneath the fascia • Perimysium: separates cells of fascicle • Endomysium: separates individual muscle fibers

  9. Fascicle • Collection of muscle fibers • Covered by blood vessels and axon of motor neurons • Each muscle fibers is separated by endomysium • It is surrounded by sarcolemma • Contains nucleus and sarcoplasmic reticulum • Each muscle fibers is composed of myofibril

  10. Myofibril & Sarcomere

  11. Sarcomere • It is a repeating pattern formed by striations

  12. Sarcomere (cont.) • Troponin: protein that works with tropomyosin to block muscle contraction until calcium ions are present • Transverse tubule: set of membranous channels that contain extracellular fluid

  13. Smooth muscle • It is shorter than skeletal muscle, and has single centrally located nuclei • It lacks troponin • It alternates between a state of relaxation and contraction

  14. Cardiac muscle • Composed of striated cells, containing a single nucleus • It has a well developed sarcoplasmic reticulum • Its transverse tubule is larger than skeletal muscle’s

  15. Contraction • Acetylcholine(ACh) is the neurotransmitter that contracts skeletal muscles • ACh binds with receptors on the motor endplate, which causes muscle impulse • Calcium ions diffuse from sarcoplasmic reticulum to sarcoplasmand binds to troponin

  16. Contraction (cont.) • Tropomyosin moves, which allows actin and myosin to link • Actin is pulled to the center of the sarcomere, which allows muscle fibers to shorten

  17. Threshold

  18. Respiration • Anaerobic breaks down glucose and releases ATP • Aerobic requires oxygen to produce ATP

  19. Oxygen debt • When cellular respiration is not able to sustain the muscle, lactic acid diffuses into the blood stream • This creates an oxygen debt, that must be repaid later

  20. Muscle fatigue • When a muscle loses its ability to contract • Most likely occurs from accumulation of lactic acid

  21. Types of contraction

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