Final answer:
Glycogen contributes to glucose supply upon breakdown, and epinephrine triggers glucose release for the 'fight-or-flight' response by binding to receptors and activating cAMP. Insulin, by binding to its receptor, leads to the translocation of the Glut-4 transporter, increasing glucose uptake and promoting glycogenesis, glycolysis, and fatty acid synthesis.
Step-by-step explanation:
How Glycogen and Epinephrine Affect the Body
Glycogen and epinephrine both bring about effects by binding to specific receptors on cell membranes and triggering a series of biochemical responses. Glycogen, when broken down, provides glucose to the body. During times of stress, epinephrine is released, binding to G-protein-linked receptors. This, in turn, activates adenylyl cyclase, which converts ATP to cyclic AMP (cAMP). The cAMP then activates protein kinases, leading to the phosphorylation of enzymes involved in glycogen breakdown, facilitating the release of glucose to provide energy for the 'fight-or-flight' response.
Insulin's Role in Glucose Uptake and Metabolism
Insulin facilitates the uptake of glucose by binding to its receptor on the cell surface. This binding initiates several protein activation cascades, resulting in a change in cell permeability. The Glut-4 transporter is translocated to the plasma membrane, allowing an influx of glucose into the cell. Insulin also promotes glycogen synthesis, glycolysis, and fatty acid synthesis, which are all essential processes for energy storage and use. Such actions are crucial for maintaining normal blood sugar levels and overall metabolic homeostasis.