Final answer:
The depression of the J point on the electrocardiogram is measured at the end of the ST segment. Measuring the depression of the J point can be useful in diagnosing certain heart conditions, such as myocardial ischemia.
Step-by-step explanation:
The depression of the J point on the electrocardiogram is measured at the end of the ST segment.
The J point is the point where the R wave ends and the ST segment begins. It represents the completion of ventricular depolarization and the beginning of ventricular repolarization.
Measuring the depression of the J point can be useful in diagnosing certain heart conditions, such as myocardial ischemia, which can cause ST segment depression.