Final answer:
An ECG typically records five waves: P, Q, R, S, and T. These correspond to different phases of the heart's electrical activity with the P wave for atrial depolarization, QRS complex for ventricular depolarization, and T wave for ventricular repolarization. A standard 12-lead ECG gives a comprehensive view of the heart's electrical function.
Step-by-step explanation:
An electrocardiogram (ECG) typically records five different waves, each corresponding to a different phase in the heart's rhythm. These waves are named P, Q, R, S, and T. The P wave represents atrial depolarization; the QRS complex, which encompasses the Q wave, R wave, and S wave together, represents ventricular depolarization; and the T wave represents ventricular repolarization. It's important to note that sometimes a U wave can be observed, but it is not always present and is less commonly discussed.
The P wave signals the start of the electrical journey as the impulse spreads from the sinoatrial node throughout the atria. The QRS complex follows as the impulse travels down the atrioventricular node, bundle of His, bundle branches, and Purkinje fibers, leading to the contraction of the ventricles. Finally, the T wave indicates the repolarization or recovery of the ventricles.
In a standard 12-lead ECG, these waves can be seen from different angles, which helps in diagnosing various cardiac conditions. The 12 leads provide a comprehensive view of the heart's electrical activity, but the most commonly graphed is the lead II potential which shows the voltage between the right arm and the left leg. Some modern medical devices even include portable ECG monitors, suggesting advancements in the technology and its integration into everyday health monitoring.