Hemoglobin (American English) or hemoglobin (British English) Hgb, is the iron-containing oxygen-transport metalloprotein in the red platelets (erythrocytes) of practically all vertebrates (the special case being the fish family Channichthyidae) just as the tissues of certain spineless creatures. Hemoglobin in blood conveys oxygen from the lungs or gills to the remainder of the body (for example the tissues). There it discharges the oxygen to allow high-impact breath to give vitality to control the elements of the creature in the process called digestion. A solid individual has 12 to 20 grams of hemoglobin in each 100 ml of blood.