GEMOGLOBIN

GEMOGLOBIN (Hb; Haemoglobinum; az gemo… va lot. globus – kura), pigmenti asosii nafaskashii odam, jonvaroni muhrador va bisyor hayvonoti bemuhra; dar tarkibi eritrositho mavjud buda, oksigenro az uzvhoi nafas ba boftaho va gazi karbonatro az boftaho ba uzvhoi nafas intiqol medihad.
Molekulai G., ki safedai murakkab ast, az qismi safedavii globin va guruhi gayrisafedavii ohandor (gema) tarkib yoftaast. Ohaki gema metavonad yak molekulai oksigenro payvast namoyad; dar in mavrid G. ba oksigemoglobin (HbO2) mubaddal megardad. Silsilai gemoglobin – oksigemoglobin az jumlai sistemahoi buferii khun buda, muvozanati kislotayu ishqorhoro tamin menamoyad. Dar ravandi oksigenro ozod kardani G. ionhoi gidrogen, fosfathoi organiki (khususan, 2,3- difosfoglitserat), namakhoi gayriorganiki, harorat va g. (yane omilhoe, ki buzurgii qarobati G.-ro nisbati oksigen vobasta ba talaboti organizm nazorat mekunand) tasiri kalon merasonand.
G. hangomi tasiri tarafayn bo gazi gubor SO (qarobati on bo G. nisbat bo oksigen 300 marotiba beshtar ast) karboksigemoglobin HbCO hosil mekunad (on nametavonad oksigenro payvast sozad). Hangomi ba G. tasir rasondani baze oksidkunandaho ohani duvalentai gema to ohani sevalenta oksid va metgemoglobin hosil meshavad (on nametavonad oksigenro payvast sozad).
Globin va gem ba hamdigar tasiri kalon merasonand: globin khosiyati gemro tagyir doda, onro ba payvast namudani oksigen qodir menamoyad; gem boshad, ba globin ustuvori mebakhshad.
Globini G.-i odam az chor zanjiri polipentidi iborat ast. Odatan, dar eritrosithoi odam qismi beshtari G.-ro HbA tashkil medihad. Ba fraksiyahoi khurdi G.-i odam HbG va HbA2 mansuband. Dar mavridi gemoglobinopatiyai modarzodi, ki khususiyati irsi dorad, G.-hoi noqis ba vujud meoyand.
Biosintezi G. dar eritrosithoi nav (eritroblastho, normablastho, retikulositho) ba vuqu mepayvandad; katabolizmi on boshad, dar eritrosithoe, ki sikli hayoti khudro ba okhir merasonand, ogoz meyobad. Hangomi az eritrosit baromadan, G.-ro safedai gaptoglobin (Hr) payvast menamoyad. Globin dar gurdaho tajziya meshavad, vale katabolizmi gema dar jigar, magzi ustukhon va sipurz surat megirad. Ohane, ki dar in mavrid ozod gashtaast, baroi sintezi molekulahoi navi G. istifoda meshavad.
Dar khun miqdori G. ba 130 – 160 g/l (dar mardho) va 120 – 140 g/l (dar zanho) barobar meboshad; past gashtani nishondodi mazkur dar barobari kohishi adadi eritrositho dar vohidi hajmi khun, nishonai anemiya niz mahsub meshavad. Miqdori G.-i tarkibi khunro bo gemometr (nig. Gemoglobinometriya) chen mekunand.
Dar khun G.-ho amalan dar eritrositho joy dorand; miqdori on dar plazmai khun 10 – 40 g/l ast (nig. Gemoglobinemiya).
Hangomi baze bemoriho G. az eritrositho ba plazma «meguzarad» (nig. Gemoliz). Boqimondai G., ki dar jomchahoi gurda jabbish nayoftaast, bo peshob khorij shuda, rangi onro tira mesozad (nig. Gemoglobinuriya).