GENERAL HISTOLOGY

MUSCLE

SKELETAL MUSCLE

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
Which myofilament makes up the THIN filaments of muscle cells?
A
actin
B
myosin
C
connectin
D
hemoglobin
Explanation: 

Detailed explanation-1: -The myofibrils are made up of thick and thin myofilaments, which help give the muscle its striped appearance. The thick filaments are composed of myosin, and the thin filaments are predominantly actin, along with two other muscle proteins, tropomyosin and troponin.

Detailed explanation-2: -Thin filaments are comprised of two actin strands, each harboring equally separated troponin complexes, which bind Ca2+ to move tropomyosin cables away from the myosin binding sites and, thus, activate systolic contraction.

Detailed explanation-3: -The I bands contain only thin (actin) filaments, whereas the A bands contain thick (myosin) filaments. The myosin and actin filaments overlap in peripheral regions of the A band, whereas a middle region (called the H zone) contains only myosin.

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