Final answer:
Insulin stimulates fatty acid synthesis by enhancing glucose uptake and conversion to fatty acids, while glucagon inhibits it by promoting the breakdown of glycogen and the release of glucose into the blood. The correct answer is Option A: Insulin stimulates, Glucagon inhibits.
Step-by-step explanation:
Regulation of Fatty Acid Synthesis
The hormones insulin and glucagon play crucial roles in the regulation of fatty acid synthesis and breakdown. Insulin is released by the pancreas in response to high blood glucose levels.
It stimulates the uptake of glucose by cells and promotes the synthesis of fatty acids, a process known as lipogenesis. Insulin also inhibits the processes of glycogenolysis and gluconeogenesis, further decreasing blood glucose levels.
In contrast, glucagon is secreted when blood glucose levels are low. It stimulates the breakdown of glycogen in the liver and skeletal muscle through a process known as glycogenolysis and encourages the production of glucose from non-carbohydrate sources via gluconeogenesis.
Both of these actions increase blood glucose levels. Glucagon also stimulates the breakdown of fatty acids, known as lipolysis, inhibiting fatty acid synthesis.
Therefore, the correct answer to the question, “What stimulates FA synthesis/what inhibits it?” is Option A: Insulin stimulates, Glucagon inhibits.
This pairing of hormonal effects ensures that when energy is plentiful, fatty acids are synthesized and stored, whereas when energy is scarce, fatty acids are mobilized for energy.