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Biology 322 Human Anatomy I

Explore the histology of skeletal muscle, including its three types (skeletal, cardiac, and smooth), cellular components, and special terminology. Learn about the anatomy of skeletal muscle, the organization of myocytes, and the force generation and contraction mechanisms. Discover the role of sarcomeres and the significance of sarcolemma, nuclei, myofibrils, transverse tubules, sarcoplasmic reticulum, and mitochondria in muscle function.

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Biology 322 Human Anatomy I

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  1. Biology 322Human Anatomy I Histology of Muscle

  2. Muscle Tissue: 3 Types: Skeletal Muscle Cardiac Muscle Smooth Muscle

  3. Skeletal Cardiac Smooth Muscle Muscle Muscle Myocytes Nuclei Striations

  4. Muscle: Special Terminology: Prefixes = Cell = Plasma membrane = Endoplasmic reticulum = Cytoskeletal Filaments =

  5. Skeletal Muscle: Always voluntary. Each myocyte connected to and controlled by an axon from a motor neuron. Because of high metabolism, myocytes must be very close to capillaries. Myocytes are all oriented parallel to long axis of muscle which is Parallel to direction which muscle pulls when it contracts & lengthens when it relaxes

  6. Prominent Organelles in Myocytes: - Sarcolemma - Nuclei - Myofibrils (highly organized bundles of myofilaments - Transverse tubules (inward extensions of sarcolemma) - Sarcoplasmic reticulum - Mitochondria Keep in mind: Even though not prominent, all other organelles also present (vesicles, ribosomes, lysosomes, Golgi apparatus, etc.

  7. Myocyte (muscle cell) Myofibril Thick & thin myofilaments

  8. Thick and thin myofilaments forming part of a myofibril

  9. Skeletal Muscle Anatomy: Each myocyte surrounded by, and firmly attached to, layer of loose connective tissue called

  10. Skeletal Muscle Anatomy: Myocytes grouped together into bundles called each fascicle surrounded by, and firmly attached to, layer of dense irregular connective tissue called

  11. Skeletal Muscle Anatomy: Entire muscle surrounded by, and firmly attached to, layer of dense irregular connective tissue called

  12. Skeletal Muscle Anatomy: All three layers of connective tissue blend together at each end of muscle. Thus force transmitted from: Myocytes Endomysium Perimysium Epimysium Tendon, bone, etc.

  13. Skeletal myocytes = VOLUNTARY Can only contract when stimulated by motor neuron Myoneural junction or Neuromuscular junction

  14. One motor neuron + All myocytes it innervates =

  15. Skeletal Muscle: 1. Myocytes and muscles always pull (exert force by contraction), they never push. They usually, although not always, pull on bone through a tendon. 2. If a sarcomere shortens, it always does so completely "All-or-none" 3. All of the sarcomeres in the entire myocyte shorten at the same time. "All-or-none" But: 4. All of the myocytes in a muscle don't always contract at the same time. No "all-or-none"

  16. Skeletal Muscle: The total force produced by a myocyte is equal to the sum of the forces produced by individual sarcomeres. Thus: More sarcomeres = more force The total force produced by a muscle is equal to the sum of the forces produced by individual sarcomeres. Thus: More myocytes = more force

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