- See under hemoglobin.
- the oxygen-carrying pigment of red blood cells that gives them their red color and serves to convey oxygen to the tissues: occurs in reduced form (deoxyhemoglobin) in venous blood and in combination with oxygen (oxyhemoglobin) in arterial blood. Symbol: Hb
coloring matter in red blood stones, 1862, shortening of hæmatoglobin (1845), from Greek haimato-, comb. form of haima (genitive haimatos) “blood” (see -emia) + globulin, a type of simple protein, from globule, formerly a word for “corpuscle of blood.”
- The red respiratory protein of red blood cells that transports oxygen as oxyhemoglobin from the lungs to the tissues, where the oxygen is readily released and the oxyhemoglobin becomes hemoglobin.
- An iron-containing protein present in the blood of many animals that, in vertebrates, carries oxygen from the lungs to the tissues of the body and carries carbon dioxide from the tissues to the lungs. Hemoglobin is contained in the red blood cells of vertebrates and gives these cells their characteristic color. Hemoglobin is also found in many invertebrates, where it circulates freely in the blood. It consists of four peptide units, each attached to a nonprotein compound called heme that binds to oxygen. See Note at red blood cell.