Page 74 - Color_Atlas_of_Physiology_5th_Ed._-_A._Despopoulos_2003

A. Ultrastructure of striated muscle fibers
Contractile Apparatus of Striated Muscle

Sarkomere

100–1000µm 10–100µm 1µm
1 Bundle of fibers 2 Muscle fiber (myocyte) 3 Myofibril
B. Sarcomere structure
6
nm
∼1.2µm
Actin Tropomyosin
Sarcomere Troponin Plate 2.11
H zone Actin filament
Actin
Z disk filament
Titin
Myosin
filament Z disk
M disk
A band 1.6µm
Myosin filament
Myosin head
Myosin molecule 10nm
I band
6nm
M disk

C. Myosin II molecule
Motor domain
Actin-
P binding
domain
Nucleotide-
2 P pocket
nm (ATP or ADP)
Regulatory light chain
Essential light chain
Neck
Shaft (150nm) (flexible) Head
61
20nm
(After D.M.Warshaw)
Despopoulos, Color Atlas of Physiology © 2003 Thieme
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