PHYSIOLOGY
MUSCLE STRUCTURE FUNCTION
|
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
|
|
|
Only thick
|
|
|
Only thin
|
|
|
Both thick and thin
|
|
|
None of the above
|
Detailed explanation-1: -The arrangement of thick myosin filaments along the myofibrils and the cell cause them to refract light and produce a dark band which is known as an A band. The anisotropic band is composed of both thick and thin filaments . Therefore the correct answer is option (C) both actin and myosin filaments.
Detailed explanation-2: -Structural arrangement of actin and myosin in A band is such that each actin filament is surrounded by 3 thick (myosin) filaments and each myosin filament is surrounded by 6 thin (actin) filaments.
Detailed explanation-3: -During contraction, the A-band stays the same width whereas the I-band and H-zone both shrink. The thick filament consists largely of myosin. Six proteins make up myosin: two heavy chains whose tails intertwine to form a supercoil and whose heads contain actin binding sites and a catalytic site for ATP hydrolysis.