What is the equation relating oxygen consumption to cardiac output and oxygen extraction?

The Fick equation is the fundamental relationship that describes the relationship between oxygen consumption, cardiac output, and oxygen extraction. It states that the amount of oxygen consumed by the body (VO2) is equal to the product of cardiac output (CO) and the difference in oxygen content between arterial and venous blood. This can be mathematically represented as:

[ \text{VO2} = \text{CO} \times (C_aO2 - C_vO2) ]

Where:

• VO2 represents the volume of oxygen consumed,

• CO denotes cardiac output,

• ( C_aO2 ) is the oxygen content of arterial blood,

• ( C_vO2 ) is the oxygen content of venous blood.

This equation effectively illustrates how much oxygen is delivered and utilized in the body, as it takes into account both the amount of blood pumped by the heart (cardiac output) and how well the tissues are extracting oxygen from that blood.

The other options, while related to physiological concepts and measurements, do not directly describe the relationship stated in the question. The Henneman equation deals with the recruitment of motor units in muscle contraction and does not pertain to oxygen consumption. The oxygen uptake equation is a more