Haemoglobin
Haemoglobin (hemoglobin) is the red pigment in the red blood cells (erythrocytes). Hemoglobins are the primary oxygen-binding proteins. Hemoglobin in red blood cells enables transport of oxygen from the lungs to the rest of the body. The red blood cells are formed in the bone marrow, when red blood cells die – hemoglobin can be used again in the production of new ones; the remainder of hemoglobin forms the basis of bilirubin (a chemical that is excreted into the bile).Hemoglobin is involved in the transport of other gases too: It carries some of the body's respiratory carbon dioxide as carbaminohemoglobin, in which CO2 is bound to the heme protein