ANATOMY

GENERAL ANATOMY

MUSCLE ANATOMY

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
What is the name of the small contractile unit of a muscle fiber?
A
Sarcomere
B
Myofibril
C
Myofilaments
D
Fascicle
Explanation: 

Detailed explanation-1: -A sarcomere is the basic contractile unit of a myocyte (muscle fibre). A sarcomere is composed of two main protein filaments (thin actin and thick myosin filaments) which are the active structures responsible for muscular contraction.

Detailed explanation-2: -The sarcomere is the smallest contractile unit in the myofibril. Sarcomeres contract because the Z-lines move closer together. As the sarcomeres contract the myofibrils contract. As the myofibrils contract the muscle cell contracts.

Detailed explanation-3: -According to sliding filament theory of muscle contraction, the actin and myosin filament slide past each other with the help of cross bridge to reduce the length of the sarcomeres. The smallest unit of muscle contraction is a sarcomere(which is delineated by Z-lines).

Detailed explanation-4: -Sarcomerum. Synonyms: Myomere, Myomerum. The sarcomere is the main contractile unit of muscle fiber in the skeletal muscle. Each sarcomere is composed of protein filaments (myofilaments) that include mainly the thick filaments called myosin, and thin filaments called actin.

Detailed explanation-5: -The sarcomere is the fundamental contractile unit of the myofibril. Z lines separate each sarcomere. The A bands, located at the center of each sarcomere, contain the thick filaments, which may overlap with thin filaments.

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