Final answer:
Insulin, produced by the pancreas, lowers blood glucose levels by promoting cellular uptake of glucose and its storage as glycogen, while glucagon increases blood glucose by stimulating glycogen breakdown and gluconeogenesis.
Step-by-step explanation:
The regulation of blood glucose levels is a complex process involving the hormone insulin, which is produced by the beta cells of the pancreas. When blood glucose levels rise, such as after eating a meal, insulin is released and works to lower glucose levels by increasing cellular uptake, primarily in muscle and liver cells, and by promoting the storage of glucose as glycogen. Insulin enhances the number of glucose transporter proteins on the cell membrane, facilitating glucose's entry into the cells where it can be used to produce ATP or stored for future energy needs. Conversely, when blood glucose levels drop, the alpha cells of the pancreas release the hormone glucagon to raise glucose levels by promoting glycogen breakdown and gluconeogenesis.