The coupling agent between electrical excitation and contraction of a muscle is said to be:: (A) Dihydropyridine receptor (DHPR), (B) Ryanodine receptor, (C) Ca++, (D) Troponin C
Answer is C. Coupling: electrical excitation travels into muscle, releases calcium & this calcium combines with troponin & causes muscle contraction. Events tills the release of calcium is electrical & after that is mechanical. T tubules contain DHPR & L tubules contain RYR.