Q. Relaxation of the muscle takes place due to I. pumping of $Ca^{2 +}$ ions in sarcoplasmic reticulum II. presence of ATP III. confirmational changes in troponin and masking the actin filament Option containing correct statement is
A) I and III
B) I and II
C) II and III
D) I, II and III
Explanation
$Ca^{2 +}$ ions binds to the troponin and unmark the tropomyosin sites for attaching ATP so that, the contraction takes place during the muscle contraction. A band never shortens. It is the light band, which slides over the I-band and causes the shortning I, H-band. In relexed state $Ca^{2 +}$ are pumped back into sarcoplasmic reticulum and this causes the troponin confirmation changes that load troponin to occupy the active site of actin filament
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.