WHY does the heart run for a lifetime without tiring? The secret is that the heart, although it works throughout a person's life, still "finds" time to rest. Our heart consists of two atria and two ventricles. The fact is that the ventricles and atria never contract simultaneously - they always work in alternating shifts. If we calculate the time during which the heart remains in a relaxed state, we get that it rests for approximately the same amount of time as it works. #healthfacts #heart #takingcareofyourhealth #rugaremedical