What organ plays a significant role in controlling blood glucose levels?

The liver plays a significant role in controlling blood glucose levels because it is responsible for regulating glucose storage and release. When blood sugar levels rise after eating, the liver helps to store excess glucose in the form of glycogen through a process called glycogenesis. Conversely, when blood sugar levels drop, such as between meals or during fasting, the liver can convert glycogen back into glucose and release it into the bloodstream through glycogenolysis and gluconeogenesis. This dual functionality helps maintain homeostasis in blood glucose levels, ensuring that the body's cells receive a steady supply of energy.

In contrast, while the pancreas is also crucial in blood glucose regulation—producing hormones like insulin and glucagon—it primarily functions as a regulator rather than a storage organ. The kidneys play a role in filtering blood and excreting waste, but do not directly control blood glucose levels. The spleen is involved in immune functions and filtering blood but does not have a role in glucose metabolism. Therefore, the liver is the correct organ associated with blood glucose control.