While the liver is the organ most associated with bilirubin, it doesn't actually produce bilirubin. Instead, bilirubin is primarily formed during the breakdown of heme, a component of hemoglobin found in red blood cells, and this process mainly occurs in the bone marrow and also within the spleen and liver (specifically in the reticuloendothelial system of these organs). The liver then processes and excretes the bilirubin.
Here's a more detailed breakdown:
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Origin of Bilirubin: Approximately 80% of bilirubin comes from the breakdown of aged or damaged red blood cells. The remaining 20% comes from other heme-containing proteins found throughout the body, particularly in the liver and muscles.
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Location of Production:
- Bone Marrow: A significant portion of bilirubin formation takes place here during the destruction of red blood cells.
- Spleen: The spleen also plays a role in filtering and breaking down old red blood cells, contributing to bilirubin production.
- Liver: The liver contains cells of the reticuloendothelial system (Kupffer cells) which are involved in the breakdown of red blood cells and other heme proteins.
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Role of the Liver: The liver's crucial role is in conjugating bilirubin, making it water-soluble, and then excreting it into the bile, which eventually leaves the body through the intestines. The liver processes bilirubin, it does not primarily produce it.
In summary, while the bone marrow, spleen, and liver (specifically Kupffer cells) contribute to bilirubin production, the liver's primary function concerning bilirubin is processing and excretion.
