Jaundice, which doesn’t have the most intuitive name, comes from the french jaunice, meaning yellowing.
It’s also sometimes referred to as icterus though, the origin of which is even less intuitive, coming from the thought that jaundice could once be cured by looking at a yellow bird, the more you know!
Anyways, as you’ve probably gathered, jaundice involves someone taking on yellow pigments, specifically in the skin and eyes.
The yellowing pigment is caused by a compound called bilirubin, a component of bile and the main cause of bruises being yellow, and after its metabolism, the yellow-ness of urine and brown-ness of feces.
So since bilirubin’s our main culprit of yellow-ness, it’s super important to know where it comes from.
As red blood cells near the end of their lifespan—which is about 120 days—they’re eaten up or phagocytosed by macrophages in the reticuloendothelial system, aka the macrophage system, where the spleen plays the largest part, but it’s also made of parts of the lymph nodes.
K so first the macrophage eats up the blood cell, and hemoglobin is broken up into heme and globin, the globin is further broken into amino acids.
The heme on the other hand is split into iron and protoporphyrin, protoporphyrin is then converted into unconjugated bilirubin, or UCB.
Unconjugated bilirubin is the form of bilirubin that’s lipid-soluble, meaning it’s not water-soluble, sometimes it’s also known as indirect bilirubin.
Albumin in the blood then binds to UCB and gives it a lift over to the liver where it’s taken up by hepatocytes, where it’s conjugated by an enzyme called uridine glucuronyl transferase (UGT), making it now water soluble.
At this point the conjugated bilirubin is secreted out the bile canaliculi where it drains into the bile ducts and sent to the gallbladder for storage as bile.
Now when you eat a donut or something, your gallbladder secretes the bile and CB, it moves through the common bile duct to the duodenum of the small intestine and is converted to urobilinogen, or UBG, by intestinal microbes in the gut.