Soon the deoxygenated red blood cells are back in the lungs, where the hemoglobin molecules will release the carbon dioxide and be recharged with life - sustaining oxygen ​ — a process that is repeated many thousands of times during a red blood cell’s life span of about 120 days.
Peagi on hapnikust vabanenud punalibled tagasi kopsudes, kus hemoglobiinimolekulid vabastavad süsinikdioksiidi ja saavad uueks koormaks elu ülalhoidva hapniku. See protsess kordub punalible umbes 120 - päevase eluea jooksul mitmeid tuhandeid kordi.