If you are hungry between meals and have no access to food, how does your body get energy?

• A. The brain uses stored fats directly for energy
• B. The pancreas secretes glucagon which is transported to the liver and is used to convert glycogen back into glucose for energy
• C. The stomach releases gastrin to release glucose
• D. The kidneys excrete glucose in urine

Answer: (B)

During fasting between meals, the body keeps blood glucose steady by signaling a release of glucose from stored supplies. When blood glucose drops, the pancreas releases glucagon. Glucagon travels to the liver and triggers glycogenolysis, the breakdown of stored glycogen into glucose, which is then released into the bloodstream to fuel cells that need it, especially the brain and red blood cells. If fasting continues and glycogen runs low, the liver can also make glucose from other sources in a process called gluconeogenesis to keep energy up. The other options don’t fit because the brain doesn’t use stored fats directly for quick energy, gastrin does not release glucose, and kidneys don’t typically excrete glucose as an energy source during normal fasting.