NETA Personal Trainer Practice Exam

How much oxygen is typically removed from the blood as it circulates through capillaries?

1. 5 mL of O2 per 100 mL of blood

2. 10 mL of O2 per 100 mL of blood

3. 15 mL of O2 per 100 mL of blood

4. 20 mL of O2 per 100 mL of blood

The correct answer is: 15 mL of O2 per 100 mL of blood

The amount of oxygen typically removed from the blood as it circulates through the capillaries is approximately 15 mL of O2 per 100 mL of blood. This figure reflects the oxygen extraction that occurs at the tissue level, where oxygen is delivered from the blood to the cells for metabolic processes. During systemic circulation, arterial blood is rich in oxygen, and as it travels through the body and reaches the capillaries, it unloads a portion of that oxygen to the tissues that need it. The body’s demands for oxygen can vary, and under resting conditions, this extraction maintains a balance between oxygen delivery and consumption. In particular, the value of 15 mL reflects an optimal level of oxygen extraction necessary for sustaining metabolic activities without compromising the oxygenation of the blood. Higher or lower amounts of oxygen extraction can occur due to various physiological conditions, such as exercise or blood disorders, which can influence the degree to which oxygen is removed from the blood during circulation. Understanding this physiological process is essential for personal trainers, who need to appreciate how the body utilizes oxygen during different levels of activity and how this impacts overall performance and endurance.