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Muslces

Muslces. Group 4. Classification. Agonist: prime mover Antagonist: reverses agonist Synergist: prevents rotation Fixator: stabilizes the origin of the prime mover. Naming (LADSNOR!). Direction of the muscle fibers Ex) transverse, rectus, oblique Relative size of muscles

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Muslces

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  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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