The cells that respond to glucagon by breaking down glycogen and releasing glucose are liver cells, specifically hepatocytes.

Here's why:

* Glucagon's Role: Glucagon is a hormone released by the pancreas when blood glucose levels are low. Its primary function is to increase blood glucose levels.

* Glycogenolysis: Glucagon binds to receptors on hepatocytes, triggering a cascade of events that leads to the breakdown of glycogen (stored glucose) into glucose. This process is called glycogenolysis.

* Glucose Release: The released glucose is then released into the bloodstream, raising blood glucose levels and providing energy to the body.

While other cells can store glycogen, only liver cells have the necessary enzymes and receptors to respond to glucagon and release significant amounts of glucose into the bloodstream.