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

What physiological process occurs during the Cori cycle in the liver?

1. Conversion of lactate to pyruvate

2. Conversion of glucose to triglycerides

3. Storage of glucose as glycogen

4. Detoxification of ammonia

The correct answer is: Conversion of lactate to pyruvate

The Cori cycle refers to the metabolic pathway in which lactate produced by anaerobic glycolysis in the muscles is transported to the liver, where it is converted back into glucose. This process is crucial during periods of intense exertion when oxygen levels are low, leading to lactate accumulation in the muscles. The correct answer highlights the conversion of lactate to pyruvate, which is the first step in gluconeogenesis within the liver. When lactate reaches the liver, it is oxidized to pyruvate by the enzyme lactate dehydrogenase. The pyruvate can then be used for gluconeogenesis, ultimately resulting in the production of glucose that can be released back into the bloodstream for use by the muscles and other tissues. This cycle helps to maintain energy levels during strenuous activities by recycling lactate into a usable form of glucose. The other processes mentioned do not specifically characterize the Cori cycle. The conversion of glucose to triglycerides relates to fat storage rather than the recycling of lactate. Storing glucose as glycogen is a separate process that does occur in the liver but is not the focus of the Cori cycle. Detoxification of ammonia involves the urea cycle and is not directly related to the conversion of lact