Excretion and the Functions of the Mammalian Liver

• Excretion


  The process of removing waste products of metabolism from the body.
• Metabolic wastes


  Waste products produced by chemical reactions in the body's metabolism.
• Carbon dioxide


  A waste product excreted from the lungs during respiration.
• Nitrogenous waste


  A type of waste excreted by the kidneys in urine, mainly in the form of urea.
• Bile pigments


  Pigments formed from the breakdown of hemoglobin in the liver, which are excreted into bile.
• Liver


  A vital organ involved in maintaining homeostasis, storing glycogen, detoxifying harmful substances, and producing urea.
• Hepatic artery


  An artery that supplies oxygenated blood to the liver.
• Hepatic vein


  A vein that carries deoxygenated blood from the liver back to the heart.
• Hepatic portal vein


  A vein that transports products of digestion from the intestines to the liver for processing.
• Hepatocytes


  Metabolically active liver cells that make up the liver lobules.
• Hepatic lobules


  Microscopic hexagonal units in the liver where various metabolic processes occur.
• Sinusoids


  Spaces within the liver lobules where blood flows, surrounded by hepatocytes.
• Kupffer cells

  Specialized macrophages found in the sinusoids of the liver, responsible for ingesting foreign particles and old red blood cells.
• Conjugated proteins

  Globular proteins with a non-protein component called a prosthetic group, serving various functions in the body.
• Hemoglobin


  A conjugated protein found in red blood cells that carries oxygen throughout the body.
• Bilirubin


  A substance formed from the breakdown of heme groups in old red blood cells, excreted in bile.
• Bile


  A fluid secreted by hepatocytes into canaliculi, then drained into bile ductules, aiding in digestion and waste excretion.
• Glycogenesis


  The process of converting glucose into glycogen for storage in the liver.
• Glycogenolysis


  The process of breaking down glycogen into glucose for energy release.
• Transamination


  The enzymatic conversion of one amino acid into another, facilitating various metabolic processes.
• Deamination


  The removal of amino groups from excess amino acids, leading to the production of ammonia.
• Ornithine cycle


  A set of enzyme-controlled reactions in the liver that converts ammonia into urea, a less toxic compound.
• Urea


  A nitrogenous waste product formed in the liver by combining ammonia and carbon dioxide, excreted in urine.
• Detoxification


  The process of rendering harmful substances less toxic or eliminating them from the body.
• Catalase


  An enzyme found in hepatocytes that breaks down hydrogen peroxide, a harmful byproduct of metabolism.
• Alcohol dehydrogenase


  An enzyme present in hepatocytes that metabolizes ethanol into acetic acid, aiding in alcohol detoxification.
• Paracetamol


  A drug metabolized by the liver, excessive intake of which can lead to liver failure.
• Insulin


  A hormone metabolized by the liver, excessive levels of which can disrupt blood sugar regulation.