I-hemostasis yomzimba womntu yenziwe ngamacandelo amathathu:

1. Uxinzelelo lomthambo wegazi ngokwawo 2. Iiplatelets zenza i-embolus 3. Ukuqaliswa kwezinto ezibangela ukujiya kwegazi

Xa senzakele, sonakalisa imithambo yegazi engaphantsi kolusu, nto leyo enokubangela ukuba igazi lingene kwizicwili zethu, kwenze imivumbo ukuba ulusu aluphelelanga, okanye igazi ukuba ulusu luphukile. Ngeli xesha, umzimba uya kuqalisa indlela yokususa igazi emzimbeni.

Okokuqala, imithambo yegazi iyancipha, inciphisa ukuhamba kwegazi

Okwesibini, iiplatelets ziqala ukuhlangana. Xa umthambo wegazi wonakele, icollagen iyavezwa. I-Collagen itsala iiplatelets kwindawo eyonzakeleyo, kwaye iiplatelets ziyanamathelana ukuze zenze iplagi. Zakha ngokukhawuleza umqobo osithintela ekuphumeni kwegazi kakhulu.

I-Fibrin iyaqhubeka nokunamathela, ivumela iiplatelets ukuba ziqhagamshelane ngokuqinileyo. Ekugqibeleni kwakheka ihlwili legazi, lithintela igazi elingakumbi ekuphumeni emzimbeni kwaye lithintela neentsholongwane ezimbi ukuba zingangeni emzimbeni wethu zivela ngaphandle. Kwangaxeshanye, indlela yokujiya emzimbeni nayo iyasebenza.

Kukho iintlobo ezimbini zeendlela zangaphandle nezangaphakathi.

Indlela yokujiya kwamalungu omzimba ngaphandle: Iqalwa ngokuchanabeka kwezicubu ezonakeleyo ekudibaneni kwegazi ne-factor III. Xa umonakalo wezicubu kunye nokuqhekeka kwemithambo yegazi, i-factor III eveziweyo yenza i-complex ene-Ca2+ kunye ne-VII kwi-plasma ukuze isebenze i-factor X. Ngenxa yokuba i-factor III eqala le nkqubo ivela kwizicubu ezingaphandle kwemithambo yegazi, ibizwa ngokuba yi-extrinsic coagulation pathway.

Indlela yokujiya kwegazi: iqalwa kukusebenza kwe-factor XII. Xa umthambo wegazi wonakele kwaye iifayibha ze-collagen ezingaphantsi komzimba zibonakala, ingenza i-Ⅻ ibe yi-Ⅻa, ize isebenze i-Ⅺ ibe yi-Ⅺa. I-Ⅺa ivuselela i-Ⅸa xa kukho i-Ca2+, ize emva koko i-Ⅸa yenze i-complex ene-Ⅷa esebenzayo, i-PF3, kunye ne-Ca2+ ukuze isebenze ngakumbi i-X. Izinto ezibandakanyeka ekujiya kwegazi kwinkqubo ekhankanyiweyo apha ngasentla zonke zikho kwi-plasma yegazi kwimithambo yegazi, ngoko ke zibizwa ngokuba yindlela yokujiya kwegazi engaphakathi.

Le nto inendima ebalulekileyo kwi-coagulation cascade ngenxa yokudibana kweendlela ezimbini kwinqanaba le-factor X Factor X kunye ne-factor V ezenza i-active factor II (prothrombin) kwi-plasma ukuya kwi-active factor IIa, (thrombin). Ezi zixa zinkulu ze-thrombin zikhokelela ekusebenzeni ngakumbi kwee-platelets kunye nokwakheka kweefayibha. Phantsi kwesenzo se-thrombin, i-fibrinogen enyibilikisiweyo kwi-plasma iguqulwa ibe yi-fibrin monomers; kwangaxeshanye, i-thrombin isebenza kwi-XIII ukuya kwi-XIIIa, okwenza ii-fibrin monomers. Imizimba ye-fibrin idibana ukuze yenze ii-polymers ze-fibrin ezinganyibiliki emanzini, kwaye zidibene zibe yinethiwekhi ukuze zivale iiseli zegazi, zenze amahlwili egazi, kwaye zigqibezele inkqubo yokuqhekeka kwegazi. Le thrombus ekugqibeleni yenza i-scab ekhusela inxeba njengoko liphakama kwaye lenze umaleko omtsha wesikhumba phantsi kweePlatelet kwaye i-fibrin isebenza kuphela xa umthambo wegazi uqhekekile kwaye uvezwe, oko kuthetha ukuba kwimithambo yegazi eqhelekileyo esempilweni ayikhokeleli ngokungacwangciswanga kumahlwili.

Kodwa ikwabonisa ukuba ukuba imithambo yakho yegazi iyaqhekeka ngenxa yokufumba kwe-plaque, kuya kubangela ukuba inani elikhulu lee-platelet liqokelelene, kwaye ekugqibeleni kwenze inani elikhulu le-thrombus ukuvala imithambo yegazi. Le yindlela ebangela isifo sentliziyo, i-myocardial infarction, kunye ne-stroke.