Glucagon is a peptide hormone released by the pancreas that increases blood glucose levels. Which statement correctly describes signaling by glucagon?
A) Glucagon initiates the cascade of glycogen synthesis in all cells.
B) Glucagon causes glycogen breakdown only in cells that express the glucagon receptor.
C) Glucagon travels in blood bound to a transport protein.
D) Glucagon stimulation of liver glucose synthesis is an example of paracrine signaling.

Question

Quizplus · Accepted Answer

Glucagon binds to the glucagon receptor, which is expressed primarily in liver cells, causing glycogen breakdown specifically in those cells. It does not initiate glycogen synthesis in all cells. Glucagon travels freely in the blood, not bound to a transport protein. Glucagon stimulation of liver glucose synthesis is an example of endocrine signaling, not paracrine signaling.

Glucagon Is a Peptide Hormone Released by the Pancreas That