Concept 3 Review

The Electrocardiogram

The body is an excellent conductor of electricity because tissue fluid contains a high concentration of ions that move in response to potential differences generated throughout the body. Potential differences (electrical impulses) generated by the heart's intrinsic conduction system are thus conducted to the body surface, where they can be detected by surface electrodes placed on the skin. By placing electrodes over the chest an observer can gain a complete picture of the heart's electrical events, which are monitored by an electrocardiograph and recorded as an electrocardiogram (ECG or EKG).

Move your mouse over a segment of the ECG to see how the intrinsic conduction of the normal heart gives rise to the classic pattern of P, QRS, and T waves. View the animation, then read the accompanying text.

P T QRS