Muscle contraction RyRs are activated by a calcium trigger, which is brought about by the flow of through the L-type calcium channels. Furthermore, cardiac muscle tend to exhibit diad (or dyad) structures, rather than triads. Excitation-contraction coupling in cardiac muscle cells occurs when an action potential is initiated by pacemaker cells in the sinoatrial node or Atrioventricular node and conducted to all cells in the heart via gap junctions. The action potential travels along the surface membrane into T-tubules (the latter are not seen in all cardiac cell types) and the depolarisation causes extracellular to enter the cell via L-type calcium channels
Cardiac monitoring usually lasting 30–60 seconds. Monitoring of the heart rate can be performed as part of electrocardiography, but it can also be measured conveniently with specific heart rate monitors. Such heart rate monitors are largely used by performers of various types of physical exercise Cardiac monitoring Cardiac monitoring generally refers to continuous or intermittent monitoring of heart activity, generally by electrocardiography, with assessment of the patient's condition relative to their cardiac rhythm. It is different from hemodynamic monitoring, which monitors the pressure and flow of blood within the cardiovascular system. The two may be performed simultaneously on critical heart patients. Cardiac