ECG electrodes are placed on the skin to:

ECG electrodes are specifically designed to record the electrical activity of the heart. When placed on the skin, these electrodes detect and amplify the electrical signals generated by the heart during its cycles of contraction and relaxation. This allows healthcare professionals to visualize the heart's rhythm, detect any abnormalities, and diagnose various heart conditions.

Each electrode captures different aspects of the heart's electrical activity, contributing to a comprehensive understanding of the heart's function through the electrocardiogram. This assessment is crucial in clinical settings for evaluating heart health, guiding treatment decisions, and monitoring the effectiveness of cardiac therapies.

The other options pertain to different physiological functions that do not relate directly to the purpose of ECG electrodes. Monitoring blood pressure, measuring heart valve activity, and assessing lung function involve distinct instruments and techniques that are not applicable to the function of ECG electrodes.