Biological Systems MCAT Practice Exam

What is the formula for calculating cardiac output?

1. Cardiac output (L/min) = Stroke volume (L/beats) x Heart rate (beats/min)

2. Cardiac output (L/min) = Stroke volume (L/beat) / Heart rate (beats/min)

3. Cardiac output (L/min) = Heart rate (beats/min) x Blood pressure (mmHg)

4. Cardiac output (L/min) = Stroke volume (L/beat) + Heart rate (beats/min)

The correct answer is: Cardiac output (L/min) = Stroke volume (L/beats) x Heart rate (beats/min)

Cardiac output is a crucial physiological parameter that represents the volume of blood the heart pumps per minute, and it can be calculated using the formula based on stroke volume and heart rate. The correct formula indicates that cardiac output is derived from the product of stroke volume and heart rate. Stroke volume, measured in liters per beat, refers to the amount of blood ejected by the left ventricle each time it contracts. Heart rate, measured in beats per minute, describes how many times the heart beats in that duration. By multiplying these two measures, one can determine the total volume of blood flowing through the circulatory system within a minute. This relationship is fundamental in cardiovascular physiology, as it highlights how both the volume of blood pumped with each heartbeat and the frequency of those heartbeats contribute to overall blood circulation. The unit of measurement for cardiac output is liters per minute, which is consistent with the units used for stroke volume and heart rate in this formula. The other formulas provided do not correctly represent the relationship between stroke volume, heart rate, and cardiac output, as they either improperly divide the two components or include irrelevant factors like blood pressure. Therefore, the formula presented is the most accurate way to determine cardiac output and reflects key concepts in the understanding