Digestive and metabolic functions of the liver include the following:
- Hepatocytes (liver cells) produce enzymes that catalyze many different chemical reactions.
- Synthesis, interconversion, and storage of many nutrients including vitamins A, D, E, K, and B12, as well as iron, and copper
- Synthesizes at least twelve non-essential amino acids (transamination)
- Synthesizes and secretes bile, which is comprised mainly of water, electrolytes, cholesterol, bile pigments, and bile salts. Bile is essential for fat digestion and the absorption of fat-soluble vitamins.
- Metabolizes carbohydrates
- Converts sugars into glycogen and regulates sugar levels in the blood, being able to store up to 20% of its weight in glycogen
- Maintains normal blood glucose, amino acids, and fatty acid concentrations
- Synthesis and release of cholesterol bound to transport proteins
- Transforms cholesterol into steroid hormones (androgens and estrogens).
- Synthesizes and breaks down fats. The liver is capable of storing up to 40% of its weight in fatty acids.
- Regulates dietary proteins and rejects those that cannot be used by the body. The liver sends neutralizing acids to break them down before sending them to the kidneys for disposal.
Other major functions of the liver include the following:
- Synthesis of such plasma proteins as certain alpha and beta globulins, albumin (which helps regulate blood volume), as well as fibrinogen and prothrombin, which are essential clotting factors, clotting factors
- Synthesizes the inactive hormone angiotensinogen
- Stores and filters blood, including the dismantling of old blood cells, recycling any usable part and preparing the rest for elimination
- Shares responsibility with the kidneys in controlling thyroid hormones, which influence metabolism.
- Phagocytosis of damaged red blood cells, bacteria, etc., accomplished by Kupffer cells
- Formation of bilirubin
- Absorption and breakdown of circulating hormones (insulin and epinephrine) and immunoglobulins
- Absorption and inactivation of lipid-soluble drugs
- Detoxification of harmful substances that enter the body by way of the stomach, respiratory system, or skin
- Regenerates itself continually, especially if damaged or parts of it are removed
