HUMAN PHYSIOLOGY
LOCOMOTION AND MOVEMENT
|
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
|
|
|
length of actin and myosin remains same
|
|
|
width of H zone decreases
|
|
|
width of A band & I band remains same
|
|
|
actin filament slides over myosin filament
|
Detailed explanation-1: -All of the following changes occur during contraction of a muscle fibre except. Width of A-band and I-band remain the same. Actin filaments slide over myosin filaments. No worries!
Detailed explanation-2: -So, the correct answer is ‘Decrease in length of actin myofilaments’.
Detailed explanation-3: -Muscle contraction occurs when sarcomeres shorten, as thick and thin filaments slide past each other, which is called the sliding filament model of muscle contraction. ATP provides the energy for cross-bridge formation and filament sliding.
Detailed explanation-4: -The A band does not shorten-it remains the same length-but A bands of different sarcomeres move closer together during contraction, eventually disappearing.
Detailed explanation-5: -Upon muscle contraction, the A-bands do not change their length i.e the length of A band remains constant. whereas the I-bands and the H-zone shorten. This causes the Z lines to come closer together.