Final answer:
The Fick Principle describes the amount of oxygen as the product of cardiac output and the a - VO2 difference, indicating the body's oxygen consumption and cardiovascular performance.
Step-by-step explanation:
The relationship that describes the amount of oxygen (O2) as the product of cardiac output (CO) and the a - VO2 difference is called the Fick Principle. The cardiac output is the volume of blood pumped by the heart in one minute, which is the product of heart rate (HR) multiplied by stroke volume (SV). The Fick Principle is a fundamental principle in cardiovascular physiology, used to measure the overall performance of the heart and the body's oxygen consumption during exercise and at rest.