Njira Yoyendetsera Mpweya wa Oxygen Pogwiritsa Ntchito Hemoglobin
Mpweya wa okosijeni ndiye "mafuta" ofunikira kwambiri kuti maselo apange mphamvu kudzera mu kupuma kwa maselo. Komabe, mpweya sunganyamulidwe wambiri pongosungunuka m'magazi. Kusungunuka kwa mpweya wa okosijeni mumagazi ndi kochepa, komwe kumafuna njira yoyendetsera bwino kwambiri. Apa ndi pomwe hemoglobin - puloteni yayikulu m'maselo ofiira amagazi - imagwira ntchito yofunika kwambiri. Hemoglobin imalola kuti mpweya utengeke m'mapapo, udutse m'mitsempha yamagazi, ndikutulutsidwa m'maselo ngati pakufunika. Nkhaniyi ikufotokoza momwe mpweya umayendera ndi hemoglobin, kuphatikizapo kapangidwe kake, njira zomangira ndi kutulutsa mpweya, komanso zinthu zomwe zimakhudza kuyanjana kwa hemoglobin.
Kapangidwe ka Hemoglobin ndi Chifukwa Chake Ndi Kofunika
Hemoglobin (Hb) ndi puloteni yovuta yomwe imapezeka mu maselo ofiira a m'magazi. Mwa anthu akuluakulu, mawonekedwe ofala kwambiri ndi hemoglobin A (HbA), yomwe imapangidwa ndi maunyolo anayi a globin: maunyolo awiri a alpha (α) ndi maunyolo awiri a beta (β). Unyolo uliwonse wa globin uli ndi gulu la heme, kotero kuti molekyulu imodzi ya hemoglobini imakhala ndi maunyolo anayi a heme.
Gulu la heme lili ndi atomu yachitsulo (Fe²⁺) pakati pake. Chitsulochi chimalumikizana mwachindunji ndi mpweya (O₂). Chifukwa chakuti pali ma heme anayi, molekyulu imodzi ya hemoglobin imatha kumangirira mamolekyulu anayi a okosijeni. Kapangidwe ka tetrameric ka hemoglobin sikuti ndi "cholandirira" mpweya wokha, komanso chinsinsi cha mphamvu zake zogwirizana: kumangirira kwa mpweya ku heme imodzi kumakhudza momwe mpweya umalumikizirana ndi ma heme ena mosavuta.
Kapangidwe ka hemoglobini kangasinthe mawonekedwe ake. Mwachidule, pali mikhalidwe iwiri ikuluikulu: mkhalidwe wa T (tense), womwe uli ndi mphamvu yochepa ya mpweya, ndi mkhalidwe wa R (womasuka), womwe uli ndi mphamvu yapamwamba. Kusintha kwa T kupita ku R ndiye maziko omangirira bwino mpweya m'mapapo ndikutulutsa bwino minofu.
Kulumikizana kwa Oxygen m'Mapapo
M'mapapo, makamaka m'mitsempha yamagazi ya alveolar, mpweya wochepa (pO₂) umakhala wokwera. Mpweya umatuluka m'magazi kuchokera ku alveoli chifukwa cha kuchuluka kwa mpweya woipa. Ukangolowa m'magazi a erythrocytes, mpweya umalumikizana ndi iron (Fe²⁺) mu heme kuti upange oxyhemoglobin (HbO₂).
Kulumikizana kumeneku si njira yophweka "yokhazikika". Pamene molekyulu imodzi ya O₂ ilumikizana, hemoglobin imakumana ndi kusintha kwa mawonekedwe komwe kumawonjezera kuyanjana kwake pamalo ena. Ichi ndi chochitika cha mgwirizano wabwino. Zotsatira zake, ubale pakati pa kuchuluka kwa hemoglobin ndi pO₂ ndi sigmoidal (mawonekedwe a S), osati mzere wowongoka. Kapangidwe ka sigmoidal aka kamapangitsa hemoglobin kukhala yogwira ntchito bwino kwambiri: imathamanga mosavuta pa pO₂ yapamwamba (mapapo) ndipo imathamanga mosavuta pa pO₂ yotsika (minofu).
Mu mkhalidwe wabwinobwino, pa alveolar pO₂ ya pafupifupi 100 mmHg, kuchuluka kwa hemoglobin kumafika pa 97–99%. Izi zikutanthauza kuti malo ambiri omangira hemoglobin amakhala ndi mpweya. Izi ndizofunikira kuti zitsimikizire kuti mpweya umakhala ndi mphamvu zambiri zonyamula mpweya panthawi yogwira ntchito.
Kuyenda kwa Oxygen mu Kuzungulira kwa Magazi
Maselo ofiira amagazi akatuluka m'mapapo, magazi a m'mitsempha yamagazi amanyamula mpweya m'thupi lonse. Mpweya m'magazi umakhalapo m'njira ziwiri: womangiriridwa ku hemoglobin (makamaka) ndi kusungunuka mu plasma (wochepa kwambiri). Mwachilengedwe, mpweya wosungunuka umakhalabe wofunikira chifukwa umatsimikizira pO₂ ndikulimbikitsa kufalikira kwa mpweya kuchokera m'magazi kupita ku minofu. Komabe, popanda hemoglobin, kuchuluka kwa mpweya m'magazi kungachepe kwambiri, chifukwa plasma singathe kusungunula mpweya wokwanira.
Hemoglobin imagwira ntchito ngati "chotetezera mpweya." Imatenga mpweya ukachuluka ndipo imautulutsa minofu ikaufuna. Njira imeneyi imasunga mpweya wokwanira ngakhale kuti minofu ikufunika kusinthasintha.
Kutulutsidwa kwa Oxygen mu Minofu
Mu minofu ya m'mimba, pO₂ ndi yotsika kuposa m'mapapo chifukwa mpweya umagwiritsidwa ntchito nthawi zonse ndi maselo popanga ATP. Mpweya umafalikira kuchokera m'mitsempha yamagazi kupita ku madzi amkati kenako n'kulowa m'maselo. Mpweya wosungunuka ukachepa, hemoglobin imayankha potulutsa mpweya womangiriridwa kuti ukhalebe wabwino.
Kutulutsidwa kwa okosijeni kumakhudzidwa ndi momwe minofu imagwirira ntchito. Minofu yogwira ntchito (monga minofu panthawi yochita masewera olimbitsa thupi) imapanga CO₂ yambiri, ma hydrogen ion ambiri (kuchepetsa pH), ndi kutentha, zonse zomwe zimalimbikitsa hemoglobin kutulutsa okosijeni mosavuta. Izi zimatsimikizira kuti okosijeni imapezeka kumene ikufunika kwambiri.
Pa avareji ya po₂ ya minofu pafupifupi 40 mmHg, kuchuluka kwa hemoglobin kumatsika kufika pafupifupi 75%. Izi zikutanthauza kuti pafupifupi 25% ya mpweya "imatsitsidwa" ku minofu yomwe ili pamalo opumulira. Pamene ntchito ikuwonjezeka, po₂ ya minofu imatha kutsika kwambiri, zomwe zimapangitsa kuti hemoglobin itulutse mpweya wambiri.
Zotsatira za Bohr: Udindo wa CO₂ ndi pH
Chimodzi mwa njira zofunika kwambiri pakulamulira kutulutsa kwa okosijeni ndi Bohr effect. Bohr effect imafotokoza kuti kuchuluka kwa CO₂ ndi kuchepa kwa pH (acidic yambiri) kumachepetsa mphamvu ya hemoglobin ku mpweya, zomwe zimasuntha curve ya dissociation oxygen kumanja. Mwanjira ina, pa pO₂ yomweyo, hemoglobin imanyamula mpweya wochepa ndikutulutsa wambiri ku minofu.
Mwa mankhwala, CO₂ imatha kuchitapo kanthu ndi madzi kuti ipange carbonic acid, yomwe kenako imagawika kukhala H⁺ ndi bicarbonate (HCO₃⁻). H⁺ imalumikizana ndi magawo ena a hemoglobin, ndikukhazikitsa mkhalidwe wake wotsika wa T. Kuphatikiza apo, CO₂ ina imatha kulumikizana mwachindunji ndi hemoglobin kuti ipange carbaminohemoglobin, yomwe imathandizanso kutulutsa mpweya. Chifukwa chake, minofu yomwe imapanga CO₂ yambiri "imapempha" mpweya wochulukirapo kudzera mu kusintha kwa malo omwe mankhwala amayikidwa m'magazi.
M'mapapo, zinthu zimasinthasintha: CO₂ imatuluka, pH imakwera, ndipo hemoglobin imapezanso mphamvu yake yayikulu yopezera mpweya, zomwe zimapangitsa kuti igwirizane mosavuta.
Zotsatira za Kutentha ndi Kagayidwe ka Kachakudya
Kutentha kumakhudzanso kukhudzana kwa hemoglobin. Kutentha kowonjezereka—monga momwe zimakhalira ndi minofu yogwira ntchito—kumasintha kamzere kogawanika kupita kumanja, zomwe zimapangitsa kuti hemoglobin itulutse mpweya mosavuta. Mosiyana ndi zimenezi, kutentha kotsika, hemoglobin imagwira ntchito yolimba kwambiri. Izi zimathandiza kuti mpweya ufike bwino ku minofu yogwira ntchito komanso yofunda.
Udindo wa 2,3-BPG mu Kusintha
Maselo ofiira a m'magazi ali ndi molekyu yofunika kwambiri yotchedwa 2,3-bisphosphoglycerate (2,3-BPG), yomwe imapangidwa ndi glycolysis. 2,3-BPG imagwirizana ndi hemoglobin yochotsedwa mpweya (yomwe yatha mpweya) ndipo imakhazikitsa T state yake, motero imachepetsa kukonda kwake mpweya. Zotsatira zake, mpweya umatulutsidwa mosavuta m'maselo.
Kuchuluka kwa 2,3-BPG kumatha kukwera m'mikhalidwe ina, monga kukhala pamalo okwera kwambiri, kuchepa kwa magazi m'thupi, kapena kuchepa kwa magazi m'thupi kosatha. Kuwonjezeka kwa 2,3-BPG kumathandiza thupi kuzolowera mwa kulimbikitsa kutulutsa kwa okosijeni m'maselo ngakhale kuti pali po₂ yochepa.
Mzere Wogawanika wa Oxygen: Mfundo Yofunika Kwambiri Yomvetsetsa Njira ya Hb
Kapangidwe ka mpweya ndi hemoglobin dissociation curve kamasonyeza ubale womwe ulipo pakati pa pO₂ ndi hemoglobin saturation. Kapangidwe ka sigmoid kamasonyeza mgwirizano. Gawo "lathyathyathya" pa pO₂ yapamwamba limathandiza kusunga saturation yayikulu m'mapapo ngakhale pO₂ itatsika pang'ono. Gawo "lotsetsereka" pa pO₂ yapakati-yotsika limapangitsa kuti kutulutsidwa kwa mpweya kukhale kogwirizana kwambiri ndi minofu: kuchepa pang'ono kwa pO₂ kungayambitse kutulutsidwa kwakukulu kwa mpweya.
Kusuntha kwa khola kupita kumanja kumasonyeza kuchepa kwa mphamvu ya okosijeni (mpweya wambiri umatulutsidwa), komwe kumachitika chifukwa cha kuchuluka kwa CO₂, kuchepa kwa pH, kutentha kwambiri, ndi kuwonjezeka kwa 2,3-BPG. Kusuntha kumanzere kumasonyeza kuwonjezeka kwa mphamvu ya okosijeni (mpweya sumasulidwa mosavuta), mwachitsanzo pakakhala CO₂ yotsika, pH yokwera, kutentha kochepa, kapena mitundu ina ya hemoglobin.
Mapeto
Kayendedwe ka mpweya kudzera mu hemoglobin ndi zotsatira za kapangidwe kabwino kwambiri ka thupi. Hemoglobin imalumikiza mpweya m'mapapo, imaunyamula kudzera m'magazi, kenako imautulutsa ku minofu ngati pakufunika kuti kagayidwe kachakudya kayendetsedwe. Kuzindikira kwa hemoglobin ku pH, CO₂, kutentha, ndi 2,3-BPG kumapangitsa kuti kugawa kwa mpweya kukhale kogwirizana: minofu yogwira ntchito kwambiri imalandira mpweya wochuluka yokha. Kumvetsetsa njira imeneyi kumathandiza kufotokoza zochitika zambiri zachipatala komanso zakuthupi, kuyambira momwe thupi limayankhira kuchita masewera olimbitsa thupi mpaka kusintha kwa thupi pamalo okwera komanso kusokonezeka kwa kayendedwe ka mpweya m'matenda osiyanasiyana.
