Which of the following choices lists a correct sequence of events following the depolarization of transverse tubules in excitation-contraction coupling in cardiac muscle?
A)Calcium release into cytosol,calcium ion influx through sarcolemma,actin and myosin attach,thin filaments slide toward the middle of sarcomeres
B)Actin and myosin attach,thin filaments slide toward the middle of sarcomeres,calcium release into cytosol
C)Calcium release into cytosol,actin and myosin attach,calcium ion influx through sarcolemma,thin myofilaments slide toward the middle of sarcomeres
D)Calcium release into cytosol,actin and myosin attach,thin filaments slide toward the middle of sarcomeres,calcium ion influx through sarcolemma
E)Calcium ion influx through sarcolemma,calcium release into cytosol,actin and myosin attach,thin myofilaments slide toward the middle of sarcomeres

Question

Which of the following choices lists a correct sequence of events following the depolarization of transverse tubules in excitation-contraction coupling in cardiac muscle?
A)Calcium release into cytosol,calcium ion influx through sarcolemma,actin and myosin attach,thin filaments slide toward the middle of sarcomeres
B)Actin and myosin attach,thin filaments slide toward the middle of sarcomeres,calcium release into cytosol
C)Calcium release into cytosol,actin and myosin attach,calcium ion influx through sarcolemma,thin myofilaments slide toward the middle of sarcomeres
D)Calcium release into cytosol,actin and myosin attach,thin filaments slide toward the middle of sarcomeres,calcium ion influx through sarcolemma
E)Calcium ion influx through sarcolemma,calcium release into cytosol,actin and myosin attach,thin myofilaments slide toward the middle of sarcomeres

Quizplus · Accepted Answer

The correct sequence starts with calcium ion influx through the sarcolemma, which triggers further calcium release into the cytosol from the sarcoplasmic reticulum. This increase in cytosolic calcium allows actin and myosin to attach, leading to the sliding of thin filaments toward the middle of sarcomeres, causing muscle contraction. This sequence is specific to cardiac muscle, where the initial calcium influx from the extracellular space (through the sarcolemma) is crucial for triggering the larger release of calcium from the sarcoplasmic reticulum, a process known as calcium-induced calcium release (CICR).

Which of the Following Choices Lists a Correct Sequence of Events