MinuteEarth

To learn more about this topic, start your googling with these keywords: Red blood cells (RBCs), also called erythrocytes, are the most common type of blood cell and the vertebrate's principal means of delivering oxygen Hemoglobin also spelled haemoglobin and abbreviated Hb or Hgb, is the iron-containing oxygen-transport metalloprotein in the red blood cells of all vertebrates as well as the tissues of some invertebrates. Bilirubin is a yellow compound that occurs in the normal catabolic pathway that breaks down heme in vertebrates. Urobilinogen is a colourless by-product of bilirubin reduction. It is formed in the intestines by bacterial action on bilirubin. About half of the urobilinogen formed is reabsorbed and taken up via the portal vein to the liver, enters circulation and is excreted by the kidney. Urobilin or urochrome is the chemical primarily responsible for the yellow color of urine. Stercobilin is the chemical responsible for the brown color of human feces. MinuteEarth is produced by Neptu