Central Sterile Services Department (CSSD) Practice Exam

When considering the primary fuel contribution from blood glucose during exercise, it's crucial to understand how the body utilizes glucose for energy. During moderate exercise, the body relies heavily on glucose, especially as it is a quick source of energy accessible from the bloodstream.

In a typical exercise scenario, the amount of blood glucose available can contribute significantly to total energy expenditure. The correct answer indicates that approximately 5 grams of blood glucose translates to about 20 kilocalories, which is a realistic estimate of what can be utilized quickly during performance. Glucose levels in the blood are not exceedingly high, and using approximately 5 grams reflects the body's metabolic efficiency and the balance it maintains between carbohydrate storage and immediate utilization.

Other options suggesting higher glucose contributions might imply an unrealistic accumulation of blood glucose available for immediate energy during exercise, as the body has limits on how much glucose can be mobilized from the blood at any given time. Blood glucose levels fluctuate, and while the body can break down glycogen stored in muscles and the liver for energy, the direct contribution from circulating glucose is relatively modest compared to that derived from these glycogen stores during prolonged or intense activity.