Where is glucagon produced and what is its effect on lipogenesis?

Glucagon is produced in the alpha cells of the Islets of Langerhans, located in the pancreas. Its primary function is to regulate glucose levels in the blood, particularly by promoting gluconeogenesis and glycogenolysis in the liver. In the context of lipogenesis, glucagon has the opposite effect, as it works to decrease fat storage by inhibiting lipogenesis, which is the synthesis of fatty acids from acetyl-CoA in liver and adipose tissue.

By understanding glucagon's role, it becomes clear that its main action is to counter insulin's effects when blood glucose levels are low, shifting the body's metabolism away from storing fats and towards mobilizing energy. Therefore, this hormone plays a critical role in maintaining energy homeostasis by reducing the formation of lipids, which aligns with the function expected in option B.