Maitiro Ekufambisa Okisijeni NeHemoglobin
Okisijeni ndiyo "mafuta" makuru emasero kuti agadzire simba kuburikidza nekufema kwemasero. Zvisinei, okisijeni haigone kutakurwa yakawanda nekungonyungudika muplasma yeropa. Kunyungudika kweokisijeni muplasma kwakaderera, zvichida sisitimu yekufambisa inoshanda zvakanyanya. Apa ndipo panotamba basa guru nehemoglobin—puroteni huru mumasero matsvuku eropa. Hemoglobin inobvumira kutorwa kweokisijeni mumapapu, kutakurwa nemidziyo yeropa, uye kuburitswa mumatishu sezvinodiwa. Chinyorwa chino chinotaura nezve mashandiro ekutakurwa kweokisijeni nehemoglobin, kusanganisira chimiro chayo, maitiro ekubatanidza nekuburitsa okisijeni, uye zvinhu zvinopesvedzera hemoglobin affinity.
Maumbirwo eHemoglobin uye Nei Ichikosha
Hemoglobin (Hb) ipuroteni yakaoma inowanikwa mumasero matsvuku eropa. Muvanhu vakuru, chimiro chakajairika ihemoglobin A (HbA), inoumbwa nemaketani mana eglobin: macheni maviri ealpha (α) uye macheni maviri ebeta (β). Cheni yega yega yeglobin ine boka reheme, zvekuti molekyuru imwe chete yehemoglobin ine maketani mana eheme.
Boka reheme rine atomu yesimbi (Fe²⁺) pakati paro. Iyi simbi inobatanidza zvakananga neokisijeni (O₂). Nekuti kune maheme mana, molekyuru imwe chete yehemoglobin inogona kusunga mamorekuru eokisijeni mana. Maumbirwo ehemoglobin tetrameric haasi "nzvimbo" chete yeokisijeni, asiwo kiyi yehunhu hwayo hwekushanda pamwe chete: kubatana kweokisijeni kune imwe heme kunokanganisa nyore nyore kubatana kweokisijeni kune mamwe maheme.
Maumbirwo ehemoglobin anogona kuchinja chimiro. Zvichitaurwa zviri nyore, pane mamiriro maviri makuru: mamiriro eT (tense), ane affinity yakaderera yeoxygen, uye mamiriro eR (relaxed), ane affinity yakakwirira. Kuchinja kweT kuenda kuR ndiyo hwaro hwekubatana kweokisijeni zvakanaka mumapapu uye kusunungurwa kwakanaka mumatishu.
Kusunga Okisijeni Mumapapu
Mumapapu, kunyanya mumapapu e alveolar, chikamu chekumanikidzwa kweokisijeni (pO₂) chakakwira. Okisijeni inopararira kubva mualveoli ichipinda muropa nekuda kwekuwedzera kwekumanikidzwa. Kana yangopinda mumasero eropa, okisijeni inosunga zvakare kune iron (Fe²⁺) iri mu heme kuti igadzire oxyhemoglobin (HbO₂).
Kubatana uku hakusi nyore "kuitika". Kana molekyuru imwe yeO₂ yakabatana, hemoglobin inochinja chimiro chemuviri iyo inowedzera kubatana kwayo kune imwe nzvimbo inotevera. Ichi ndicho chiitiko chekubatana kwakanaka. Nekuda kweizvozvo, hukama huripo pakati pekuzara kwehemoglobin nepO₂ i sigmoidal (chimiro cheS), kwete mutsetse wakatwasuka. Chimiro ichi chesigmoidal chinoita kuti hemoglobin ishande zvakanaka: inochaja zviri nyore papO₂ yakakwira (mapapu) uye inoburitsa simba rayo papO₂ yakaderera (matishu).
Mumamiriro ezvinhu akajairwa, pa alveolar pO₂ inosvika 100 mmHg, hemoglobin saturation inosvika 97–99%. Izvi zvinoreva kuti nzvimbo zhinji dzinosunga hemoglobin dzine oxygen. Izvi zvakakosha kuti pave nechokwadi chekuti oxygen inokwana zvakakwana panguva yekushanda.
Kutakurwa kweOkisijeni Mukufamba Kwemhepo
Mushure mekunge masero matsvuku eropa abuda mumapapu, ropa retsinga rinotakura okisijeni mumuviri wese. Okisijeni muropa inowanikwa mumhando mbiri: yakabatana nehemoglobin (zvikuru) uye yakanyungudika muplasma (shoma kwazvo). Mupfungwa, okisijeni yakanyungudika inoramba yakakosha nekuti inosarudza pO₂ uye inokurudzira kupararira kweokisijeni kubva muropa kuenda kumatishu. Zvisinei, pasina hemoglobin, huwandu hweokisijeni muropa hwaizoderera zvakanyanya, sezvo plasma yaizotadza kunyungudutsa okisijeni yakakwana.
Hemoglobin inoshanda se "buffer" yeoxygen. Inogamuchira okisijeni kana yawanda uye inoiburitsa kana nyama dzichiida. Iyi nzira inochengetedza okisijeni yakagadzikana pasinei nekuchinja-chinja kwekuda kwenyama.
Kuburitswa kweOkisijeni muMiviri
Mumasero emuviri, pO₂ yakaderera pane iri mumapapu nekuti okisijeni inoshandiswa nemasero kugadzira ATP. Okisijeni inopararira kubva mu capillaries ichipinda mumvura ye interstitial yozopinda mumasero. Okisijeni yakanyungudika painoderera, hemoglobin inopindura nekuburitsa okisijeni yakabatana kuti irambe yakaringana.
Kuburitswa kweokisijeni kunokonzerwa nemamiriro emuviri. Nyama inoshanda (semuenzaniso, tsandanyama panguva yekurovedza muviri) inogadzira CO₂ yakawanda, mahydrogen ions akawanda (anoderedza pH), uye kupisa, zvese izvi zvinokurudzira hemoglobin kuburitsa okisijeni zviri nyore. Izvi zvinoita kuti okisijeni iwanikwe chaipo painonyanya kudiwa.
Paavhareji ye pO₂ yemuviri inenge 40 mmHg, hemoglobin saturation inoderera kusvika pa75%. Izvi zvinoreva kuti inenge 25% yeokisijeni inoburitswa munyama padzinenge dzazorora. Sezvo kushanda kuchiwedzera, pO₂ yemuviri inogona kuderera zvakanyanya, zvichiita kuti hemoglobin ibudise okisijeni yakawanda.
Mhedzisiro yeBohr: Basa reCO₂ nepH
Imwe yenzira dzakakosha mukutonga kuburitswa kweokisijeni iBohr effect. Bohr effect inotsanangura kuti kuwedzera kweCO₂ uye kudzikira kwepH (acid yakawanda) kunoderedza kubatana kwehemoglobin neokisijeni, zvichichinja curve yekuparadzanisa okisijeni kuenda kurudyi. Nemamwe mashoko, papO₂ imwecheteyo, hemoglobin inotakura okisijeni shoma uye ichaburitsa yakawanda kumatishu.
Panyaya yemakemikari, CO₂ inogona kusangana nemvura kuti igadzire carbonic acid, iyo inobva yapatsanuka kuita H⁺ nebicarbonate (HCO₃⁻). H⁺ inosunga kune zvimwe zvikamu zvehemoglobin, zvichiita kuti T yayo ive isina hukama hwakakwana. Pamusoro pezvo, imwe CO₂ inogona kusunga zvakananga kuhemoglobin kuti igadzire carbaminohemoglobin, iyo inotsigirawo kuburitswa kweokisijeni. Saka, matishu anoburitsa CO₂ yakawanda anongoerekana "akumbira" okisijeni yakawanda kuburikidza nekuchinja kwemakemikari eropa.
Mumapapu, mamiriro acho anochinja: CO₂ inoburitswa, pH inokwira, uye hemoglobin inodzoreredza simba rayo remhepo, zvichiita kuti ikwanise kusunganidzwa zviri nyore.
Mhedzisiro yeTembiricha uye Basa reMetabolic
Kupisa kunokanganisawo kubatana kwehemoglobin. Kupisa kwakanyanya—sekunge mutsandanyama dzinoshanda—kunowanzo chinja curve yekupatsanurwa kuenda kurudyi, zvichiita kuti zvive nyore kuti hemoglobin ibudise okisijeni. Kusiyana neizvi, pakupisa kwakaderera, hemoglobin inowanzo chengeta okisijeni zvakanyanya. Izvi zvinobatsira pakupararira kweokisijeni zvakanyanya kumatishu anoshanda, anodziya.
Basa re2,3-BPG muKuchinjika
Masero matsvuku eropa ane molekyuru inokosha inonzi 2,3-bisphosphoglycerate (2,3-BPG), chinhu chinobva muglycolysis. 2,3-BPG inosungana nehemoglobin isina oxygen (yapera oxygen) uye inodzikamisa T state yayo, nokudaro ichideredza kuda kwayo oxygen. Nekuda kweizvozvo, oxygen inoburitswa nyore nyore mumatishu.
Mazinga e2,3-BPG anogona kuwedzera mune mamwe mamiriro ezvinhu, akadai sekugara munzvimbo dzakakwirira, anemia, kana kushaya hope kwenguva refu. Kuwedzera kwe2,3-BPG kunobatsira muviri kuchinjika nekukurudzira kuburitswa kweokisijeni yakawanda mumatishu pasinei nekushomeka kwepO₂ yenzvimbo.
Kuparadzanisa Okisijeni: Chinhu Chinokosha Pakunzwisisa Hb Mechanism
Kupatsanurwa kweoxygen-hemoglobin kunoratidza hukama huripo pakati pepO₂ nekuzara kwehemoglobin. Chimiro chesigmoid chinoratidza kubatana. Chikamu "chakatsetseka" papO₂ yakakwira chinobatsira kuchengetedza kuwanda kwakanyanya mumapapu kunyangwe pO₂ ichidonha zvishoma. Chikamu "chakatetepa" papO₂ yapakati-yakaderera chinoita kuti kuburitswa kweokisijeni kugamuchire zvakanyanya munyama: kudzikira kudiki kwepO₂ kunogona kutungamira mukuburitswa kweokisijeni yakakura zvikuru.
Kuchinja kwekona kuenda kurudyi kunoratidza kudzikira kwekubatana (oxygen yakawanda inoburitswa), kunokonzerwa nekuwedzera kweCO₂, kudzikira kwepH, kuwedzera kwetembiricha, uye kuwedzera kwe2,3-BPG. Kuchinja kuruboshwe kunoratidza kuwedzera kwekubatana (oxygen haibudiswi nyore nyore), semuenzaniso kana paine CO₂ yakaderera, pH yakakwira, tembiricha yakaderera, kana mamwe marudzi ehemoglobin.
Mhedziso
Maitiro ekufambisa okisijeni nehemoglobin anokonzerwa nekugadzirwa kwakanaka kwazvo kwemuviri. Hemoglobin inosunga okisijeni mumapapu pamwe chete, yoifambisa kuburikidza nekutenderera kweropa, yozoiburitsa mumatishu sezvinodiwa kuti metabolic process ishande. Kunzwa kwehemoglobin ku pH, CO₂, tembiricha, uye 2,3-BPG kunoita kuti kugoverwa kweokisijeni kuenderane: matishu anoshanda anogamuchira okisijeni yakawanda otomatiki. Kunzwisisa maitiro aya kunobatsira kutsanangura zviitiko zvakawanda zvekiriniki uye zvemuviri, kubva pakupindura kwemuviri kukurovedza muviri kusvika pakuchinja panzvimbo dzakakwirira uye kutakurwa kweokisijeni zvisina kunaka muzvirwere zvakasiyana-siyana.
