Bilirubin

Bilirubin is a yellow breakdown product of haem (heme in American English). Haem is a special ring shaped molecule that is found in haemoglobin and is essential to the oxygen carrying capacity of blood.

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Bilirubin is essentially a waste product, formed when red blood cells die and haemoglobin is broken down. Haemoglobin is broken down within the macrophages to haem and globin; the haem is further degraded to Fe2+, carbon monoxide and bilirubin via the intermediate compound biliverdin. Since bilirubin is poorly soluble in water, it is carried to the liver bound to albumin. Bilirubin is made water soluble in the liver by conjugation with uridine diphosphoglucuronic acid or UDPGA. As part of bile, the soluble or "conjugated" bilirubin then passes through the common bile duct and is either temporarily stored in the gallbladder or passes right away into the gut. Some of the excreted bilirubin may be reabsorbed from the gut (entero-hepatic circulation). Bacteria in the intestines modify bilirubin to form stercobilinogen, causing the brown color of feces. The yellow colour of urine is a result of urobilin, another breakdown product of bilirubin.

Breakdown: Breakdown can refer to:...

Haem: REDIRECT Heme...

American English: American English (AmE) is the form of the English language used mostly in the United States of America. It is the primary language used in the United States. As of 2005, more than two-thirds of native speakers of English use various forms of American English. American English is also sometimes calle...