Muscle CSM 1040 Dr' Melanie Osterhouse

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Muscle CSM 1040Dr. Melanie Osterhouse

• Fxn of m skeletal m. is about 40 of body mass
• a.
• b.
• c. d.

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Types
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Location and function

• Smooth walls of hollow visceral organs like
  stomach and bladder
• Forces fluids thru
• Cardiac only in heart
• Pumps blood
• Skeletal
• movement

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Functional characteristics

• Excitability
• Contractility unique to m.
• Extensibility
• elasticity

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Histology (slide 127)

• Bundle of sticks (m. fibers) surrounded by C.T.
  called ___________
• A cluster of perimysium-surrounded bundles- is
  surrounded by dense irregular C.T. called
  __________
• _______ - plasma membrane of m. fiber
• ________- m. fiber cytoplasm
• ________- each m. fiber composed of ______
• Each m. has 1 n., 1 a., 1 v. enters center of
  m. and branch through the CT sheets

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Slide 130 and 129

• Explain thick and thin filaments and bands
• Thick are _______ and thin are ______
• (do people demo)
• Thin filament is troponin and tropomyosin
• Tropomyosin blocks myosin heads from binding
• Troponin binds Ca2

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Slide 133 132

• Action potential -gt Ca2 release -gt C12 binds to
  troponin -gt troponin exposes binding site for
  thick filament -gt ATP hydrolyzed so myosin head
  binds -gt ADP P released -gt myosin head rotates
  causing contraction -gt ATP binds to myosin -gt
  myosin head released from actin and recocks

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Where does all the ATP come from?

• Regeneration of the hydrolyzed ATP
• ____________ - high energy molec stored in m
• ________ ADP-gtcreatine ATP
• __________- makes lactic acid (m. soreness)
• After creatine is used up
• Break down ________ stored in m.
• For large amts of ATP for moderate periods (40
  sec)
• ______ - prolonged light to moderate exercise
• Occurs in mitochondria

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Aerobic

• Where does the O2 come from
• _____- similar to Hb but in m. -gtstores o2
• Glucose o2 -gt CO2 H2O ATP
• 36 ATP per glucose but sluggish due to many steps

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m. fatigue

• Cannot contract m. even if still being stimulated
  (not just tired)
• ________ - no ATP to unhook cross bridge stays
  contracted (ex. Rigor mortis lets go when
  tissue breaks down, writers cramp)
• _______ - extra O2 the body must take in for
  restorative processes
• Why you rapidly breathe after stopping exercise

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Motor unit

• Motor unit Motor n. and all m. fibers it
  supplies
• When motor n. fires, all m. fibers it innervates
  contract
• Fine motor control (eyeball) have few fibers per
  n.
• Large m. that are less precise (hip m.) have lots
  of fibers per n.

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Where does the Ca2 come from (slide 128)

• ____________- stores Ca2 and releases it on
  demand ( during an action potential for ex.)
• Surrounds each myofibril
• ______- continuation of sarcolemma that conducts
  the impulses and orders the release of Ca2

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Terms (slide 137)

• ______ moving part
• _______ immovable or less moveable bone
• _____ same tension (same weight)
• Concentric contraction - ________ (picking up
  book)
• Eccentric contraction - _________(putting it
  back)
• ________- same length (not lenthen or shorten)
• Adding wt. but not moving
• ______- even when relaxed, m. are almost always
  slightly contracted