Bilirubin:

A yellowish bile pigment that is formed during the breakdown of red blood cells in the liver and bone marrow. It is then released into the bloodstream and excreted in the bile.

Formation:

Bilirubin is produced when heme, the iron-containing component of hemoglobin, is broken down. This process primarily occurs in the reticuloendothelial system, which includes the liver and spleen.

Transport:

After its formation, bilirubin binds to albumin and is transported through the bloodstream to the liver. It is carried to the liver for further processing and elimination.

Processing in the Liver:

In the liver, bilirubin is conjugated with glucuronic acid to form conjugated bilirubin. This conjugated form of bilirubin is water-soluble and can be excreted in the bile.

Excretion:

Conjugated bilirubin is then excreted in the bile and enters the digestive tract. It gives bile its characteristic yellowish color and plays a role in the digestion and absorption of fats.

Measurement:

Bilirubin levels in the blood can be measured through a simple blood test. Elevated levels may indicate liver disease or abnormalities in the breakdown of red blood cells.