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Section 39: Muscle – Micro-and Macro-Structure
39-1
MicroscopicMicroscopic-Macroscopic pStructure of
Sk l t lSkeletal MuscleMuscle
39-2 From: Brown
Muscle Structure• Structural unit of skeletal muscle is the
multinucleated muscle cell or fiber (thickness: 10-100 μm, length: 1-30 cm
• Muscle fibers consist of myofibrilsMuscle fibers consist of myofibrils (sarcomeres in series: basic contractile unit of muscle)unit of muscle)
• Myofibrils consist of myofilaments (actin and myosin)and myosin)
39-3 From: Brown
Muscle Architecture - Micro
• Key Words:• sarcomere• Actin -double strand, woundActin double strand, wound• Myosin- twisted golf clubs, heads
facing out in a spiral fashion down the bundled tails
• titan• Z- line , M - line• cross bridges • Contractile mechanism
39-4 From: Legh
Muscle Structure (continued)• Composition of sarcomere
– Z line to Z line (≅ 1.27-3.6 μm in length)e to e ( 3 6 μ e gt )– Thin filaments (actin: 5 nm in diameter)– Thick filaments (myosin: 15 nm inThick filaments (myosin: 15 nm in
diameter)– Myofilaments in parallel with sarcomereMyofilaments in parallel with sarcomere– Sarcomeres in series within myofibrils
39-5 From: Brown
Microsoft® Encarta® Online Encyclopedia 2004 http://encarta.msn.com© 1997 2004 Microsoft Corporation All Rights Reserved© 1997-2004 Microsoft Corporation. All Rights Reserved.
39-6 From: GarnerMarieb, 1997
39-7 From: GarnerMarieb, 1997
39-8 From: GarnerMarieb, 1997
39-9 From: GarnerMarieb, 1997
39-10 From: GarnerNigg & Herzog, 1998
Muscle Architecture - Micro
• Key Words:• sarcomere• Actin -double strand, woundActin double strand, wound• Myosin- twisted golf clubs, heads
facing out in a spiral fashion down the bundled tails
• titan• Z- line , M - line• cross bridges • Contractile mechanism
39-11 From: Legh
39-12 From: Garner
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