Answer: Liver

The human liver is a critical organ that plays a major role in the regulation of glycogen storage, decomposition of red blood cells, hormone production, detoxification, and aiding digestion, among other things. While the number of estimated functions the liver performs varies dependent on how you measure and classify those functions, roughly 500 different biological functions are attributed to the liver.

As such, it’s no surprise that the liver, a veritable power house of metabolic processes and critical to our survival, is the largest internal organ by both weight and volume—the average adult liver is around 1.44–1.66 kilograms (3.2–3.7 pounds) in weight and approximately 885-1,220 milliliters in volume. What’s interesting is that while liver size is dependent on gender and general size (larger males have, as you would presume, larger livers), age also plays a role. Babies have a significantly larger liver-to-total-body-mass ratio than adults, a state of affairs that hints at the importance of the liver’s role in metabolic regulation.