Final answer:
Adrenaline stimulates glycogen breakdown in skeletal muscle cells by activating the ß-adrenergic receptors, leading to an increase in cyclic AMP. Cyclic AMP then activates protein kinase A, which phosphorylates enzymes involved in glycogen metabolism. This results in the degradation of glycogen into glucose, providing energy for the muscle cell.
Step-by-step explanation:
Adrenaline, also known as epinephrine, stimulates glycogen breakdown in skeletal muscle cells by activating the ß-adrenergic receptors. This activation leads to an increase in cyclic AMP (CAMP) inside the cell. Cyclic AMP then activates PKA, which phosphorylates two enzymes: glycogen phosphorylase kinase (GPK) and glycogen synthase (GS). GPK promotes the degradation of glycogen by activating glycogen phosphorylase (GP), while phosphorylation of GS inhibits its ability to form glycogen from glucose. As a result, glycogen is broken down into glucose to provide a ready pool of energy for the muscle cell in response to adrenaline, such as during the fight or flight response.