Our largest internal organ, the liver, is also one of the most versatile — it performs over 500 different functions. Virtually all its functions are performed by hepatocytes (literally, “liver cells”). Here, one of the liver’s 200 billion hepatocytes looms greatly enlarged, busily carrying out five of these vital functions — represented by familiar visual metaphors.
- Conversion of protein (and other compounds) to glucose — a group of processes known as gluconeogenesis. Here, a ham (high in protein content) is converted to some candies (mostly sugar).
- Glucose storage and release — the conversion of glucose to glycogen (and back again) — plays a major role in the regulation of blood sugar levels. (Here, glycogen is represented as a slice of bread — not quite glycogen, but it’s made of starch, another long-chain carbohydrate.)
- Secretion of bile, containing among its components bile salts, molecules that bind to fats on one side, and water on the other. In doing so, they stabilize — in other words, emulsify — small drops of fat, making them more available for efficient enzymatic digestion. The green dish detergent is an apt metaphor in two ways. First, it works much the same way as bile salts, emulsifying the grease on your dishes so it can be washed away. Second, bile is in fact green! The color comes from bilirubin, another component of bile, which serves to excrete broken down red blood cells and has a strong color (which changes depending on the exact compound) owing to its iron content.
- Secretion of blood proteins, such as albumins — represented here by egg whites (which do contain albumins as a major component). Among other roles, blood proteins modify the osmotic balance of your blood, preventing it from losing too much fluid in your capillary beds.
- Metabolism of drugs and poisons, typically converting them into a form that can be more easily excreted by the kidney into the urine.