Upon stimulation of skeletal muscles calcium is immediately made available for binding to troponin from

Options

(a) blood
(b) lymph
(c) sarcoplasmic reticulum
(d) bone

Correct Answer:

sarcoplasmic reticulum

Explanation:

The sarcoplasmic reticulum is a specialized type of smooth ER that regulates the calcium ion concentration in the cytoplasm of striated muscle cells. A system of membrane-bound tubules that surrounds muscle fibrils, releasing calcium ions during contraction and absorbing them during relaxation. The endoplasmic reticulum found in striated muscle fibers.