American Board of Surgery Qualifying Exam (ABS QE) Practice Test

What effect does the Cori cycle have in the body?

1. Converts lactate to glucose in muscle

2. Transports glucose to adipose tissue

3. Glucose to lactate in muscle

4. Converts glucose to triglycerides in the liver

The correct answer is: Glucose to lactate in muscle

The Cori cycle primarily functions to recycle lactate produced during anaerobic glycolysis back into glucose. When muscle cells engage in intense exercise, they may rely on anaerobic metabolism, leading to glucose breakdown into pyruvate, which is then converted to lactate due to insufficient oxygen. This lactate is released into the bloodstream and transported to the liver. In the liver, lactate undergoes gluconeogenesis, undergoing conversion back to glucose. This newly synthesized glucose can then re-enter circulation and be utilized by muscles or other tissues, providing a critical energy source during prolonged or strenuous activity. Thus, the cycle plays a significant role in maintaining energy balance in the body, especially under anaerobic conditions. The chosen answer highlights the conversion of glucose to lactate in muscle, which is part of the cycle's process but does not capture the essence of the Cori cycle's main role. The cycle specifically emphasizes the conversion of lactate back to glucose in the liver even though lactate is indeed produced in the muscles. Understanding that the Cori cycle connects muscle activity and liver function constitutes its significance in energy metabolism, especially during periods of high energy demand when the body temporarily resorts to anaerobic pathways.