During prolonged fasting or intense exercise, which organs release glucose?

During prolonged fasting or intense exercise, which organs release glucose?

• A. Heart and lungs
• B. Skeletal muscles and adipose tissue
• C. Liver and kidney
• D. Pancreas and spleen

Answer: (C)

During prolonged fasting or intense exercise, the liver and kidneys are primarily responsible for glucose production and release into the bloodstream. The liver plays a critical role in maintaining blood glucose levels during these states. It performs gluconeogenesis, a metabolic pathway that synthesizes glucose from non-carbohydrate sources, such as amino acids and glycerol, and it can also break down glycogen stores to release glucose when needed. The kidneys also contribute, particularly through gluconeogenesis, especially during prolonged fasting. They can produce glucose from amino acids and other precursors, helping to supplement the glucose available to the body during times of low availability from dietary sources. In contrast, other options do not accurately describe the primary function of the listed organs during fasting or intense exercise. For instance, the heart and lungs are involved in oxygenation and circulation, not glucose release. Skeletal muscles primarily utilize glucose but do not release it into circulation under these conditions; instead, they may use glycogen stores. Adipose tissue primarily stores fat and releases fatty acids during fasting. The pancreas plays a critical role in regulating blood glucose levels through insulin and glucagon but does not release glucose itself, and the spleen has no significant role in glucose metabolism.

During prolonged fasting or intense exercise, the liver and kidneys are primarily responsible for glucose production and release into the bloodstream.

The liver plays a critical role in maintaining blood glucose levels during these states. It performs gluconeogenesis, a metabolic pathway that synthesizes glucose from non-carbohydrate sources, such as amino acids and glycerol, and it can also break down glycogen stores to release glucose when needed.

The kidneys also contribute, particularly through gluconeogenesis, especially during prolonged fasting. They can produce glucose from amino acids and other precursors, helping to supplement the glucose available to the body during times of low availability from dietary sources.

In contrast, other options do not accurately describe the primary function of the listed organs during fasting or intense exercise. For instance, the heart and lungs are involved in oxygenation and circulation, not glucose release. Skeletal muscles primarily utilize glucose but do not release it into circulation under these conditions; instead, they may use glycogen stores. Adipose tissue primarily stores fat and releases fatty acids during fasting. The pancreas plays a critical role in regulating blood glucose levels through insulin and glucagon but does not release glucose itself, and the spleen has no significant role in glucose metabolism.