GENERAL HISTOLOGY

MUSCLE

SKELETAL MUSCLE

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
Which myofibril is a large bundle of proteins with contractile heads sticking out all throughout the bundle?
A
Myosin
B
Actin
C
Troponin
D
Tropomyosin
Explanation: 

Detailed explanation-1: -Most of the cytoplasm consists of myofibrils, which are cylindrical bundles of two types of filaments: thick filaments of myosin (about 15 nm in diameter) and thin filaments of actin (about 7 nm in diameter).

Detailed explanation-2: -The thick filament, myosin, has a double-headed structure, with the heads positioned at opposite ends of the molecule. During muscle contraction, the heads of the myosin filaments attach to oppositely oriented thin filaments, actin, and pull them past one another.

Detailed explanation-3: -The myofibrillar protein components most important for muscle fiber structure are actin and myosin. They are the most abundant proteins in muscle and are directly involved in the ability of muscle to contract and to relax.

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