Metabolic and Endocrine Regulation Quiz

See Hormonal Influences on Metabolism. Option A is correct. After a meal, glucose is plentiful in the blood, and the pancreas releases insulin, an anabolic hormone (one that promotes storing fuel rather than releasing it). Insulin's message is to store fuel, not to break it down or make more. It therefore stops the pathways that release or make glucose and fuel: gluconeogenesis (making new glucose, mainly in the liver), glycogenolysis (breaking glycogen down), lipolysis (breaking fat down), proteolysis (breaking protein down) and ketogenesis (making ketone bodies). At the same time it starts storage: GLUT4-mediated glucose uptake into muscle and fat, glycogen synthesis, protein synthesis and lipogenesis. So the liver does not make more glucose when plenty is arriving from the gut. In the fasting state, the roles reverse as glucagon rises. A useful rule is that insulin stops the "making and releasing" pathways and starts the "storing" pathways. The question asks which listed process insulin suppresses, and only gluconeogenesis belongs on the "stop" list; the other four are on the "start" list.

• Insulin: an anabolic hormone that promotes storing fuel after a meal.
• Suppressed: gluconeogenesis, the making of new glucose, mainly in the liver.
• Stimulated: GLUT4 glucose uptake, glycogen synthesis and lipogenesis.