Muscular Tissue

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DonnaT
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91423
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Muscular Tissue
Updated:
2011-06-20 23:30:26
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Muscular Tissue
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Muscular Tissue
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  1. three types of muscular tissue
    skeletal, cardiac, and smooth
  2. cardiac muscle and smooth muscle are regulated by neurons that are part of the
    • autonomic (involuntary) division of the nervous system
    • and by hormones released by endocrine glands
  3. Muscular tissue has four key functions
    • producing body movements,
    • stabilizing body positions,
    • storing and moving substances within the body,
    • generating heat.
  4. thermogenesis is
    As muscular tissue contracts, it produces heat
  5. Properties of Muscular Tissue
    • Electrical excitability (action potentials)
    • Contractility
    • Exstendiblity
    • Elasticity
  6. Electrical excitability
    a property of both muscle and nerve cells

    • is the ability to respond to certain stimuli by producing electrical signals
    • called action potentials.
    • Action
    • potentials can travel along a cell's plasma membrane due to the presence of
    • specific voltage-gated channels.
  7. muscle cells, two main types of stimuli trigger action potentials.
    • One is autorhythmic electrical signals arising in the muscular tissue itself, as in the heart's pacemaker.
    • The other is chemical stimuli, such as neurotransmitters released by neurons, hormones distributed by the blood, or even local changes in pH.
  8. Contractility
    • the ability of muscular tissue to contract forcefully when stimulated by an
    • action potential
  9. Extensibility
    the ability of muscular tissue to stretch without being damaged
  10. Elasticity
    • ability of muscular tissue to return to its original length and shape after
    • contraction or extension.
  11. Which connective tissue coat surrounds groups of
    muscle fibers, separating them into fascicles
    Perimysium bundles groups of muscle fibers into fascicles
  12. The subcutaneous layer or hypodermis
    • is composed of areolar connective tissue and adipose tissue
    • It provides a pathway for nerves, blood vessels, and lymphatic vessels to enter and exit muscles.
  13. . Fascia (FASH-ē-a = bandage) what is it?
    • is a dense sheet or broad band of irregular connective tissue that lines the
    • body wall and limbs and supports and surrounds muscles and other organs of the
    • body.
  14. Fascia - what does it do?
    • allows free movement of muscles,
    • carries nerves, blood vessels, and lymphatic vessels,
    • and fills spaces between muscles
  15. Three layers of connective tissue extend from the fascia to protect and
    strengthen skeletal muscle
    • Epimysium
    • Perimysium
    • Endomysium
  16. Epimysium
    • Outermost layer
    • encirculing the entire muscle
  17. Perimysium
    • surrounds groups of 10 to 100 or more muscle fibers, separating them into
    • bundles called fascicles (FAS-i-kuls =
    • little bundles).
  18. Endomysium
    • Penetrating the interior of each fascicle and separating individual muscle fibers from one another
    • a thin sheath of areolar connective tissue.
  19. Definition of a tendon:
    • a cord of dense regular connective tissue composed of parallel bundles of
    • collagen fibers that attach a muscle to the periosteum of a bone
  20. what is aponeurosis
    • When the connective tissue elements extend as a broad, flat layer, the tendon
    • ie the epicranial aponeurosis on top of the skull between the frontal and occipital
    • bellies of the occipitofrontalis muscle
  21. what are somatic motor neurons
    The neurons that stimulate skeletal muscle to contract
  22. capillaries
    • bring in oxygen and nutrients
    • and remove heat and the waste products of muscle
    • metabolism
  23. myoblasts
    • each skeletal muscle fiber arises during embryonic development from the fusion
    • of a hundred or more small mesodermal cells called myoblasts
  24. Which structure shown here releases calcium ions
    to trigger muscle contraction
    The sarcoplasmic reticulum releases calcium ions to trigger muscle contraction
  25. Muscle action potentials travel along the:
    • the sarcolemma and through the T tubules, quickly spreading throughout the muscle fiber.
    • This arrangement ensures that an action potential excites all parts of the muscle fiber at essentially the same instant.
  26. Myofibrils contain two types of filaments:
    • thick filaments
    • and thin filaments
  27. Which of the following is the smallest: muscle
    fiber, thick filament, or myofibril? Which is largest
    • thick filament, smallest
    • myofibril,
    • muscle fiber - largest
  28. How are sarcomeres separated from one another
    Sarcomeres are separated from one another by Z discs
  29. Z discs
    • Narrow, plate-shaped regions of dense material that separate one sarcomere
    • from the next.
  30. A band
    • The dark, middle part of the sarcomere that extends the entire length of the thick filaments
    • and also includes those parts of the thin filaments that overlap with the thick filaments.
  31. I band
    • The lighter, less dense area of the sarcomere that contains the rest of the thin filaments but no thick filaments.
    • A Z disc passes through the center of each I band
  32. H zone
    A narrow region in the center of each A band that contains thick filaments but no thin filaments.
  33. M line
    A region in the center of the H zone that contains proteins that hold the thick filaments together at the center of the sarcomere.
  34. Myofibrils are built from three kinds of proteins:
    • (1) contractile proteins, which generate force during contraction;
    • (2) regulatory proteins, which help switch the contraction process on and off;
    • (3) structural proteins, which keep the thick and thin filaments in the proper alignment, give the myofibril elasticity and extensibility, and link the
    • myofibrils to the sarcolemma and extracellular matrix.
  35. two contractile proteins in muscle
    • myosin
    • and actin
  36. Myosin
    • functions as a motor protein in all
    • three types of muscle tissue.
  37. What do Motor Protiens do?
    • Motor proteins push or pull various cellular structures to achieve movement by
    • converting the chemical energy in ATP to the mechanical energy of motion or the
    • production of force
  38. Contractile proteins (myosin and actin)
    what do they do?
    • generate force during contraction;
    • regulatory proteins (troponin and
    • tropomyosin) help switch contraction on and off.


































      • (a)
    • A thick filament contains about 300 myosin molecules, one of which is shown
    • enlarged. The myosin tails form the shaft of the thick filament, and the myosin
    • heads project outward toward the surrounding thin filaments.


      • (b)
    • Thin filaments contain actin, troponin, and tropomyosin.
  39. Which proteins connect into the Z disc? Which
    proteins are present in the A band? In the I band?
    • Actin and titin anchor into the Z disc.
    • A bands contain myosin, actin, troponin, tropomyosin, and titin;
    • I bands contain actin, troponin, tropomyosin, and titin

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