The plasma membrane of the muscle fibre is called

Contraction of a muscle is caused by

The myosin binding site is located on ..........

Identify the muscle which represents the following characteristics and choose the correct option accordingly.
$I.$ Transportation of food through the digestive tract.
$II.$ Transportation of gametes through the genital tract.

$A -$ Calcium ions $(Ca^{2+})$ activate the interaction between myosin and actin filaments.
$R -$ The cross-bridge is formed in the presence of $ATP,$ and the breaking of the cross-bridge also requires the binding of a new $ATP$ molecule.

Muscle fatigue occurs due to the accumulation of: