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Medicine LibreTexts

22.7E: Liver Function

  • Page ID
    8048
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    The liver is thought to be responsible for up to 500 separate functions.

     

    LEARNING OBJECTIVES

     

    List some of the functions of the liver

     

    KEY TAKEAWAYS

    Key Points

     

    • The liver is thought to be responsible for up to 500 separate functions, usually in combination with other systems and organs.
    • The various functions of the liver are carried out by the liver cells or hepatocytes.
    • Excessive alcohol consumption can cause liver disease.
    • The liver tissue of an alcoholic may become clogged with fats and adversely affect liver function.

     

    Key Terms

     

    • liver disease: Also called hepatic disease, this is an umbrella term referring to damage to or disease of the liver.
    • IGF: A hormone similar in molecular structure to insulin. It plays an important role in childhood growth and continues to have anabolic effects in adults. A synthetic analog of IGF-1, mecasermin is used for the treatment of growth failure.

     

    Functions of the Liver

     

    The human liver is thought to be responsible for up to 500 separate functions, usually in combination with other systems and organs. The various functions of the liver are carried out by the liver cells or hepatocytes. Currently, there is no artificial organ or device capable of emulating all the functions of the liver.

    This is an anatomical drawing of a human chest from the front. The liver can be seen within the diaphragm and above the gall bladder and stomach.

     

    The liver: The liver, or hepar, is a vital organ present in vertebrates and some other animals. It has a wide range of functions including detoxification, protein synthesis, and the production of the biochemicals necessary for digestion.

    The liver is the mainstay of protein metabolism— it synthesizes as well as degrades. It performs several roles in carbohydrate and lipid metabolism. The bulk of the lipoproteins are synthesized in the liver.

    This is a micrograph of an overstressed liver from an alcoholic. A healthy liver can break down alcohol. However, the overstressed liver of an alcoholic may become clogged with fats that adversely affect liver function. This type of tissue is most common in alcoholic hepatitis (a prevalence of 65%) and alcoholic cirrhosis (a prevalence of 51%).

     

    Liver tissue of an alcoholic: A healthy liver can break down alcohol. However, the overstressed liver of an alcoholic may become clogged with fats that adversely affect liver function. This type of tissue is most common in alcoholic hepatitis (a prevalence of 65%) and alcoholic cirrhosis (a prevalence of 51%).

    In the first- trimester fetus, the liver is the main site of red blood cell production. By the 32nd week of gestation, the bone marrow has almost completely taken over that task.

    The liver also produces the insulin -like growth factor 1 (IGF-1), a polypeptide protein hormone that plays an important role in childhood growth and continues to have anabolic effects in adults.

    The liver stores a multitude of substances, including glucose (in the form of glycogen), vitamin A (1–2 years’ supply), vitamin D (1–4 months’ supply), vitamin B12 (1–3 years’ supply), iron, and copper. The liver is responsible for immunological effects, acting as a sieve for the antigens that are carried to it via the portal system.

    The liver synthesizes angiotensinogen, a hormone that is responsible for raising blood pressure when the angiotensinogen is activated by renin, an enzyme that is released when the kidney senses low blood pressure.

    The liver breaks down or modifies toxic substances, such as alcohol and most medicinal products, in a process called drug metabolism. This sometimes results in toxication, when the metabolite is more toxic than its precursor.

    Preferably, the toxins are conjugated to avail excretion in bile or urine. The liver breaks down insulin and other hormones.