PHYSIOLOGY
MUSCLE CONTRACTION
|
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
|
Z-lines move apart during muscle relaxation because
|
|
Calcium ions are added to troponin in actin filaments
|
|
|
Calcium ions are added to tropomyosin in actin filaments
|
|
|
Calcium ions are removed from troponin in actin filaments
|
|
|
Calcium ions are removed from tropomyosin in actin filaments
|
Explanation:
Detailed explanation-1: -Powered by ATP, it pumps calcium ions back into the sarcoplasmic reticulum, reducing the calcium level around the actin and myosin filaments and allowing the muscle to relax.
Detailed explanation-2: -When a sarcomere shortens, some regions shorten whereas others stay the same length. A sarcomere is defined as the distance between two consecutive Z discs or Z lines; when a muscle contracts, the distance between the Z discs is reduced.
Detailed explanation-3: -Troponin is shown in red (subunits not distinguished). Upon binding calcium, troponin moves tropomyosin away from the myosin-binding sites on actin (bottom), effectively unblocking it.
There is 1 question to complete.