Question

Histological and physiological study of skeletal muscle shows that the 

A. Distance between two Z lines remains constant during contraction. 

B. Width of the anisotropic A band is constant during contraction. 

C. Tension developed is maximal when actin and myosin molecules just fail to overlap. 

D. Stimulus needed to cause contraction is minimal when applied at the Z line. 

E. The T system of transverse tubules opens into the terminal cisterns of the sarcoplasmic reticulum.

Answer 1

A. False This is sarcomere length and it shortens with contraction. 

B. True Its width is the length of the myosin molecule. 

C. False It is maximal when action and myosin overlap maximally and when adjoining actin molecules just fail to overlap. 

D. True This is where the transverse tubules penetrate the muscle fibre. 

E. False They are adjacent but are not directly connected.