Adrenaline stimulates glycogen breakdown in liver cells

Steps:

• Adrenaline binds to liver cell receptors, activating the fight-or-flight response.
• This triggers cAMP production, which activates protein kinase A.
• Protein kinase A phosphorylates glycogen phosphorylase, initiating glycogenolysis.
• Glycogen breaks down to glucose-1-phosphate, converted to glucose for blood release.

Why A is correct:

• Adrenaline promotes glycogenolysis via the hormonal control pathway, raising blood glucose for energy during stress, as defined in endocrine physiology.

Why the others are wrong:

• B: Urea formation is stimulated by glucagon or high-protein diets, not adrenaline.
• C: Protein breakdown is cortisol-driven, not adrenaline's primary liver effect.
• D: Glucose-to-glycogen conversion (glycogenesis) is insulin-stimulated, opposing adrenaline's action.

Final answer: A