histology 1.12: molecular basis of cross-striation and muscle contraction lm micrographs of striated...
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HISTOLOGY 1.12: MOLECULAR BASIS OF CROSS-STRIATION HISTOLOGY 1.12: MOLECULAR BASIS OF CROSS-STRIATION AND MUSCLE CONTRACTIONAND MUSCLE CONTRACTION
LM micrographs of striated muscleLM micrographs of striated muscle
Low power EM micrographLow power EM micrograph
High power EM micrographHigh power EM micrograph
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Structure of the myofibrils
Myofilaments:
Thick (myosin)
Thin (actin)
Sarcomer: 2,2-2,5 m
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Myofilaments 1. The thin filament
F-actin (made up by
several G-actins)
Further proteins involved:
6-9 nm
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Arrangement of the myosin molecules within the filament (250-350 molecule/filament)
Bipolar structure
Myofilaments 2. The thick filament
Building block: the myosin molecule
12- 15 nm
Heads
L-chains H-chains
Myosin heads
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The „sliding filament” mechanism of the contraction
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Cytoskeletal proteins within the sarcomer
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The sarcoplasmic reticulum and the transverse tubular system (T-system)
triads
Triad: T-tubule + two adjacent terminal cisterns of the sarcoplasmic reticulum
Sarcoplasmic reticulumLongitudinal tubules
Terminal cisterns