Final answer:
Glucagon is the pancreatic hormone that stimulates the liver to break down glycogen into glucose, which increases blood sugar levels. It is secreted by alpha cells in the pancreas and acts in opposition to insulin, which is released from beta cells.
Step-by-step explanation:
The pancreatic hormone that stimulates the liver to break down glycogen into glucose to increase the blood sugar level is glucagon. This hormone is released from alpha cells in the pancreas when the body requires additional energy or is in a state of starvation. Glucagon orchestrates the process of glycogenolysis in the liver, where glycogen is converted back into glucose and then released into the bloodstream, thereby raising blood glucose levels. The actions of glucagon are counterbalanced by insulin, which is released from beta cells in the pancreas in response to elevated blood glucose levels, stimulating the uptake of glucose by cells and promoting the conversion of glucose into glycogen for storage in the liver. Together, these hormones maintain blood glucose homeostasis in a negative-feedback system.