Which organ is primarily responsible for glycogen storage in the body?

The liver is primarily responsible for glycogen storage in the body. Glycogen is a form of stored glucose, which serves as a key energy reserve. When blood glucose levels are high, such as after a meal, the liver takes up excess glucose and converts it into glycogen through a process called glycogenesis. This stored glycogen can later be converted back into glucose when the body requires energy, such as between meals or during physical activity.

The liver's unique role in regulating blood sugar levels and its capacity to store large amounts of glycogen make it critical for maintaining overall metabolic homeostasis. The liver can store about 100 grams of glycogen in an adult, releasing glucose into the bloodstream when it’s needed, ensuring that the body's energy supply is stable.

In contrast, the pancreas primarily produces hormones like insulin and glucagon that regulate blood sugar levels rather than storing glycogen. The kidneys have roles in filtering blood and regulating electrolytes and waste products but are not involved in glycogen storage. The heart's main function is to pump blood and does not play a role in glycogen storage either. Consequently, the liver stands out as the organ chiefly responsible for this crucial metabolic process.