The contraction of the myosin actin system in cardiac muscle cells is triggered by a rise in intracellular Ca 2 Cardiac muscle cells have specialized Ca 2 channels called ryanodine receptors because of their sensitivity to the drug ryanodine that are embedded in the membrane of the sarcoplasmic ret...

The fact that the ryanodine receptors in cardiac muscle cells are opened by Ca2 itself rather than by IP3gated channels as in the endoplasmic reticulu ...

The contraction of the myosin actin system in cardiac muscle cells is triggered by a rise in

Question:

The contraction of the myosin actin system in cardiac muscle cells is triggered by a rise in intracellular Ca²⁺. Cardiac muscle cells have specialized Ca²⁺ channels called ryanodine receptors because of their sensitivity to the drug ryanodine that are embedded in the membrane of the sarcoplasmic reticulum, a specialized form of the endoplasmic reticulum. In contrast to the IP³-gated Ca²⁺channels in the endoplasmic reticulum shown in Figure 16−23, the signaling molecule that opens ryanodine receptors is Ca²⁺ itself. Discuss the consequences of this feature of ryanodine channels for cardiac muscle cell contraction.

Figure 16−23