Biochem 15: Glycogen Metabolism

Energy availability is rarely constant. In this episode, Medlock Holmes turns his attention to glycogen — the body’s answer to unpredictability.Glycogen metabolism is revealed as a system designed not for abundance, but for transition. We explore how glucose is stored efficiently as a highly branched polymer, how rapid mobilisation is achieved when demand rises, and why liver and muscle glycogen serve fundamentally different purposes despite sharing the same chemistry.Drawing on Lehninger’s pathway logic and Harper’s clinically grounded treatment of glycogen synthesis and breakdown, this episode highlights regulation as the central theme. Hormonal signals, allosteric control, and tissue-specific priorities work together to ensure that glycogen is neither hoarded uselessly nor depleted recklessly.Medlock learns that glycogen is not simply stored energy. It is insurance. When this insurance fails — through enzyme defects or regulatory breakdown — the consequences are immediate and often dramatic, particularly in tissues with high and fluctuating energy demand.This episode shows that metabolism plans ahead, even when the future is unknown.Key Topics Explored* Structure and advantages of glycogen* Glycogenesis and glycogenolysis* Liver versus muscle glycogen roles* Hormonal regulation by insulin and glucagon* Allosteric control and rapid responsiveness* Clinical glycogen storage disorders This is a public episode. If you'd like to discuss this with other subscribers or get access to bonus episodes, visit drmanaankarray.substack.com/subscribe