Final answer:
With a total lack of normal electrical activity in the heart, the expected heart rate or pulse would be absent or extremely low, potentially leading to cardiac arrest. Cardiopulmonary resuscitation (CPR) can manually maintain circulation in such emergencies. During physical exertion, cardiac output is affected by heart rate and ventricular filling time.
Step-by-step explanation:
In the presence of a total lack of normal electrical activity in the heart, one would expect the heart rate or pulse to be absent or extremely low. This is because the electrical activity of the heart is responsible for initiating the contractions that result in the heartbeat. Without this, the cardiac output, which is a combination of heart rate and stroke volume, would drastically fall, potentially leading to cardiac arrest or death if not swiftly treated.
Cardiopulmonary resuscitation (CPR) is an emergency technique applied when the heart stops, using chest compressions to artificially maintain blood circulation, especially to vital organs like the brain. In a healthy individual during intense physical activity, when the heart rate increases, the cardiac output can initially remain stable or even rise. However, if the rate becomes too high, this can lead to decreased cardiac output due to insufficient ventricular filling time during diastole.