What is the role of the liver in metabolism?

The liver plays a crucial role in metabolism, primarily through its functions of detoxification and processing of nutrients. It is responsible for converting excess glucose into glycogen for storage, which can later be converted back into glucose when the body needs energy. The liver also metabolizes fats and proteins, contributing to the synthesis of important biochemicals like cholesterol and specialized proteins necessary for blood clotting.

Moreover, the liver detoxifies harmful substances, such as drugs and alcohol, transforming them into less harmful compounds that are excreted from the body. This detoxification process is vital for maintaining overall metabolic balance and ensuring that the body's internal environment remains stable.

The other options describe functions that do not accurately represent the primary metabolic role of the liver. Circulating blood is mainly the function of the heart, storing oxygen is a role of muscle cells and the respiratory system, and producing antibodies is primarily performed by the immune system, specifically by B cells in response to pathogens. Thus, the liver's key contributions to metabolism through nutrient processing and detoxification make it a vital organ for maintaining metabolic health.