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julianne.elizabeth
on FreezingBlue Flashcards.
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Female and Male
female skeletal muscle makes up 36% of body mass
male skeletal muscle makes up 42% of body mass
muscle strength per unit is the same in both sexes
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With Age...
With age, connective tissue increases and muscle fiber decreases
By age 30, loss of muscle mass (sarcopenia) begins
regular exercise reverses sarcopenia
Atheroscerosis may block distal arteries, leading to intermittent claudication and sever pain in leg muscles
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Muscular Dystrophy
Group of inherited muscle-destroying diseases
Muscles enlarge due to fat and connective tissue deposits
Muscle fibers astrophy
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Duchenne Muscular Dystrophy (DMD)
Most common and sever type
Inherited, sex linked, carried by femailed and expressed in males (1/3500) as lack of dystrophin
Victims become clumsy and fall frequently; usually die of respiratory failure in their 20s
no cure, but Viral gene therapy or infusion of stem cells with correct dystrophin genes show promise
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Regeneration
Cardiac and Skeletal cells become amitotic, but can lengthen and thickn
Myoblast like skeletal muscle cells have limited regenerative ability
Injured heart muscle is mostly replaced by connective tissue
-Smooth muscle regenerates throughout life
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Development and formation
All muscle tissue develop from embryonic myoblasts
Multinucleated skeletal muscle cells form by fusion
Growth factor agrin stimulates clusting of ACh receptors at neuromuscular junctions
Cardiac and smooth muscle myoblasts develop gap junctions
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Developmental Aspects
muscular development reflects neuromuscular coordination
Development occurs head to toe, and promixmal to distal
peak natural neural control occurs by mid-adolescence
Athletics and training can improve neuromuscular control
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