After a high-carbohydrate meal, glucose levels in the bloodstream rise. Which of the following correctly describes how the body manages this influx of glucose?

• A. The liver immediately converts all excess glucose into fat since glycogen storage is limited.
• B. Skeletal muscles store glucose as glycogen & can later release it into the bloodstream during fasting.
• C. The liver & muscles both perform glycogenesis, but only the liver can release stored glucose back into circulation when blood sugar levels drop.
• D. Glycogenolysis occurs in the liver to store excess glucose for future energy needs.

Answer: (C)

Verified step by step guidance

1. Step 1: Understand the key terms in the problem. 'Glycogenesis' refers to the process of converting glucose into glycogen for storage, while 'glycogenolysis' refers to breaking down glycogen into glucose to release it into the bloodstream when needed.
2. Step 2: Analyze the role of the liver and muscles in glucose management. The liver and skeletal muscles both store glucose as glycogen through glycogenesis. However, only the liver has the ability to release glucose back into the bloodstream during fasting or low blood sugar levels, due to the presence of the enzyme glucose-6-phosphatase.
3. Step 3: Evaluate the incorrect statements. The liver does not immediately convert all excess glucose into fat; it first prioritizes glycogen storage. Skeletal muscles store glycogen for their own energy needs and cannot release it into the bloodstream because they lack the enzyme glucose-6-phosphatase.
4. Step 4: Confirm the correct statement. The correct description is that both the liver and muscles perform glycogenesis to store glucose as glycogen, but only the liver can release stored glucose back into circulation when blood sugar levels drop.
5. Step 5: Conclude by noting that glycogenolysis is not a storage process but rather the breakdown of glycogen to release glucose, which occurs in the liver to maintain blood sugar levels during fasting or energy demand.