The red corpuscle is a cell from 5 t o 7 m icr on s of diameter. lt transport oxygen from th e lung s to tissues celfs with its small structure by mans of the adhesion of oxygen to the hemog lob i n , e l em e nt whose main component is iron . T he red c orpu sc l e also catalyses the bicarbonate formation start i ng from water and carbon diox ide, product of breat hing , so that the latter returns t o th e l ung s dis sol ved in blood , to be eliminated , maintaining thi s w a y cells and tissues viable . These sanguine cells transport suc h a tiny qu a nt i ty of hemog · lobin that it is measured in picogram s (Pg); it only oc c upies one vol ume in the space measured in femtolitters ( FI ) . The erythrocyte production h appens in the bon e marrow of high species as fa s t as app roximate l y 35.000 . 000 cells per second , the y liv e 100 d ays in average and die in similar quantities. The se r ed corpuscles are depos ited in th e sp l een to re cycl e their components afte r whi c h th e bon e m ar row w i ll assemble new cells . In consequence , a 450 kilogram-weight an imal w i ll have about 300 trillion ce ll s circu l ating its v asc ular system .