Question

The ECG waves on the tracing actually represent the action potentials that are occurring in the myo-cardiocytes (heart muscle cells). Why do the waves in an ECG always precede the mechanical events (systole \& diastole) of the heart?

Answer 1

The ECG waves precede the mechanical events of the heart because they represent the action potentials that trigger heart contractions. The sequence of electrical signals, such as the P wave, QRS complex, and T wave, initiate the mechanical events that follow, like systole and diastole.

Step-by-step explanation:

The waves in an ECG represent the action potentials in the heart muscle cells and always precede mechanical events due to the sequence of electrical events that trigger heart contractions. The P wave indicates atrial depolarization, the QRS complex signifies ventricular depolarization, and the T wave represents ventricular repolarization. The action potentials initiate the process of muscle contraction, so mechanical events like systole and diastole occur after their corresponding electrical signals are detected on the ECG tracing. The electrical signals set off a cascade of events that lead to myocardial contraction, propelling blood through the heart’s chambers and onward into the circulatory system. This sequential process ensures efficient operation of the cardiac cycle, coordinating the heart’s electrical and mechanical activities.