Platelets (thrombocytes) yog cov khoom me me ntawm cytoplasm tso tawm los ntawm cytoplasm ntawm cov laus Megakaryocyte hauv cov pob txha pob txha.Txawm hais tias Megakaryocyte yog tsawg kawg ntawm cov hlwb hematopoietic hauv cov pob txha pob txha, suav txog tsuas yog 0.05% ntawm tag nrho cov pob txha pob txha nucleated hlwb, cov platelets lawv tsim yog qhov tseem ceeb heev rau kev ua haujlwm hemostatic ntawm lub cev.Txhua Megakaryocyte tuaj yeem tsim 200-700 platelets.
Cov platelet suav ntawm ib tus neeg laus ib txwm yog (150-350) × 109 / L.Platelets muaj kev ua haujlwm ntawm kev tswj xyuas kev ncaj ncees ntawm cov hlab ntsha phab ntsa.Thaum cov platelet suav txo mus rau 50 × Thaum cov ntshav siab qis dua 109 / L, qhov kev raug mob me me lossis tsuas yog nce ntshav siab tuaj yeem ua rau cov ntshav stasis ntawm daim tawv nqaij thiab submucosa, thiab txawm tias loj purpura.Qhov no yog vim tias platelets tuaj yeem nyob ntawm phab ntsa vascular txhua lub sijhawm los sau cov qhov khoob uas tshuav los ntawm endothelial cell detachment, thiab tuaj yeem fuse rau hauv vascular endothelial hlwb, uas tuaj yeem ua lub luag haujlwm tseem ceeb hauv kev tswj hwm endothelial cell ncaj ncees lossis kho cov hlwb endothelial.Thaum muaj cov platelets tsawg dhau lawm, cov haujlwm no nyuaj ua kom tiav thiab muaj kev xav los ntshav.Cov platelets nyob rau hauv cov ntshav ncig feem ntau yog nyob rau hauv lub xeev "stationary".Tab sis thaum cov hlab ntsha puas lawm, platelets tau qhib los ntawm kev sib cuag saum npoo thiab kev ua ntawm qee yam coagulation.Activated platelets tuaj yeem tso tawm ntau yam khoom tsim nyog rau cov txheej txheem hemostatic thiab kev ua haujlwm ntawm lub cev xws li adhesion, aggregation, tso tawm, thiab adsorption.
Platelet tsim Megakaryocyte kuj tau los ntawm hematopoietic qia hlwb hauv cov pob txha pob txha.Hematopoietic qia hlwb ua ntej sib txawv rau hauv megakaryocyte progenitor hlwb, tseem hu ua colony forming unit megakaryocyte (CFU Meg).Cov chromosomes nyob rau hauv lub nucleus ntawm progenitor cell theem yog feem ntau 2-3 ploidy.Thaum cov hlwb progenitor yog diploid lossis tetraploid, cov hlwb muaj peev xwm loj hlob, yog li qhov no yog theem thaum cov kab Megakaryocyte nce cov cell.Thaum cov hlwb megakaryocyte progenitor sib txawv ntxiv rau hauv 8-32 ploidy Megakaryocyte, cytoplasm pib sib txawv thiab Endomembrane system maj mam ua tiav.Thaum kawg, cov tshuaj membrane cais cov cytoplasm ntawm Megakaryocyte mus rau ntau qhov chaw me me.Thaum txhua lub cell sib cais tag, nws dhau los ua platelet.Ib tug los ntawm ib tug, platelets poob los ntawm Megakaryocyte los ntawm qhov sib txawv ntawm lub endothelial hlwb ntawm lub sinus phab ntsa ntawm cov hlab ntsha thiab nkag mus rau hauv cov ntshav.
Muaj cov khoom tiv thaiv kab mob sib txawv kiag li.TPO yog glycoprotein feem ntau tsim los ntawm ob lub raum, nrog rau qhov hnyav molecular ntawm kwv yees li 80000-90000.Thaum platelets hauv cov hlab ntsha txo qis, qhov concentration ntawm TPO hauv cov ntshav nce.Lub luag haujlwm ntawm qhov kev tswj hwm no suav nrog: ① txhim kho DNA synthesis hauv cov hlwb progenitor thiab nce cov cell polyploids;② Txhawb nqa Megakaryocyte los tsim cov protein;③ Ua kom tag nrho cov naj npawb ntawm Megakaryocyte, ua rau cov platelet ntau lawm.Tam sim no, nws ntseeg tau tias kev loj hlob thiab kev sib txawv ntawm Megakaryocyte feem ntau yog tswj hwm los ntawm ob txoj cai tswj hwm ntawm ob theem ntawm kev sib txawv.Ob qhov kev tswj hwm no yog megakaryocyte Colony-stimulating factor (Meg CSF) thiab Thrombopoietin (TPO).Meg CSF yog ib qho kev tswj hwm uas feem ntau ua rau theem ntawm cov progenitor cell, thiab nws lub luag haujlwm yog los tswj kev loj hlob ntawm megakaryocyte progenitor hlwb.Thaum tag nrho cov naj npawb ntawm Megakaryocyte hauv cov pob txha pob txha txo qis, qhov kev tsim cov txheej txheem tswj hwm no nce ntxiv.
Tom qab platelets nkag mus rau hauv cov hlab ntsha, lawv tsuas muaj lub cev muaj zog rau thawj ob hnub, tab sis lawv qhov nruab nrab ntawm lub neej tuaj yeem yog 7-14 hnub.Hauv physiological hemostatic kev ua ub no, platelets lawv tus kheej yuav disintegrate thiab tso tawm tag nrho cov active tshuaj tom qab aggregation;Nws kuj tseem tuaj yeem koom ua ke hauv vascular endothelial hlwb.Ntxiv nrog rau kev laus thiab kev puas tsuaj, platelets kuj tseem tuaj yeem noj thaum lawv lub cev ua haujlwm.Kev laus platelets yog engulfed nyob rau hauv tus po, lub siab, thiab lub ntsws cov ntaub so ntswg.
1. Ultrastructure ntawm platelets
Raws li ib txwm muaj, platelets tshwm sim me ntsis convex discs ntawm ob sab, nrog rau qhov nruab nrab txoj kab uas hla ntawm 2-3 μ m.Qhov nruab nrab ntim yog 8 μ M3.Platelets yog cov hlwb nucleated uas tsis muaj cov qauv tshwj xeeb nyob rau hauv lub tshuab ntsuas qhov muag, tab sis cov txheej txheem ultrastructure tuaj yeem pom nyob rau hauv lub tshuab ntsuas hluav taws xob.Tam sim no, cov qauv ntawm cov platelets feem ntau muab faib rau thaj tsam ib puag ncig, thaj chaw sol gel, thaj chaw Organelle thiab thaj chaw tshwj xeeb membrane.
Qhov chaw platelet ib txwm yog du, nrog cov qauv me me pom, thiab yog qhov qhib canalicular system (OCS).Cov cheeb tsam ib puag ncig ntawm platelet nto yog tsim los ntawm peb qhov chaw: txheej txheej, chav tsev membrane, thiab thaj tsam submembrane.Lub tsho tiv no yog tsim los ntawm ntau yam glycoproteins (GP), xws li GP Ia, GP Ib, GP IIa, GP IIb, GP IIIa, GP IV, GP V, GP IX, thiab lwm yam. mus rau TSP, thrombin, collagen, fibrinogen, thiab lwm yam. Nws yog ib qho tseem ceeb rau platelets los koom rau hauv coagulation thiab kev tiv thaiv kab mob.Lub tsev membrane, tseem hu ua plasma membrane, muaj cov protein ntau nyob rau hauv lipid bilayer.Tus naj npawb thiab kev faib tawm ntawm cov khoom no cuam tshuam nrog platelet adhesion thiab coagulation muaj nuj nqi.Lub membrane muaj Na + - K + - ATPase, uas tswj cov ion concentration sib txawv sab hauv thiab sab nraud daim nyias nyias.Lub submembrane cheeb tsam yog nyob nruab nrab ntawm qhov qis ntawm chav tsev membrane thiab sab nraud ntawm microtubule.Submembrane cheeb tsam muaj submembrane filaments thiab Actin, uas muaj feem xyuam rau platelet adhesion thiab aggregation.
Microtubules, microfilaments thiab submembrane filaments kuj muaj nyob rau hauv thaj av gel ntawm platelets.Cov tshuaj no ua rau lub cev pob txha thiab kev cog lus ntawm cov platelets, ua lub luag haujlwm tseem ceeb hauv platelet deformation, particle tso tawm, ncab, thiab clot contraction.Microtubules yog tsim los ntawm Tubulin, suav txog 3% ntawm tag nrho cov platelet protein.Lawv lub luag haujlwm tseem ceeb yog tswj cov duab ntawm platelets.Microfilaments feem ntau muaj Actin, uas yog cov protein ntau tshaj plaws hauv platelets thiab suav txog 15% ~ 20% ntawm tag nrho cov platelet protein.Submembrane filaments yog cov khoom siv fiber ntau, uas tuaj yeem pab Actin-binding protein thiab Actin crosslink rau hauv pob ua ke.Ntawm qhov chaw ntawm lub xub ntiag ntawm Ca2 +, actin koom tes nrog prothrombin, contractin, khi cov protein, co actin, myosin, thiab lwm yam kom tiav platelet zoo hloov, pseudopodium tsim, cell contraction thiab lwm yam kev ua.
Table 1 Main Platelet Membrane Glycoproteins
Lub Organelle cheeb tsam yog thaj chaw uas muaj ntau hom Organelle hauv platelets, uas muaj kev cuam tshuam tseem ceeb rau kev ua haujlwm ntawm platelets.Nws tseem yog ib qho kev tshawb fawb hotspot nyob rau hauv cov tshuaj niaj hnub.Cov khoom tseem ceeb tshaj plaws hauv cheeb tsam Organelle yog ntau yam, xws li α Particles, cov khoom ntom ntom (δ Particles) thiab Lysosome (λ Particles, thiab lwm yam., saib Table 1 kom paub meej.α Granules yog qhov chaw khaws cia hauv platelets uas tuaj yeem tso cov protein.Muaj ntau tshaj kaum hauv txhua platelet α Particles.Table 1 teev tsuas yog cov ntsiab lus tseem ceeb, thiab raws li tus kws sau ntawv tshawb fawb, nws tau pom tias α Muaj ntau dua 230 qib ntawm platelet derived yam (PDF) tam sim no hauv cov granules.Dense particle ratio α Cov khoom me me me me, nrog txoj kab uas hla ntawm 250-300nm, thiab muaj 4-8 ntom ntom hauv txhua platelet.Tam sim no, nws tau pom tias 65% ntawm ADP thiab ATP tau khaws cia hauv cov khoom ntom ntom hauv cov platelets, thiab 90% ntawm 5-HT hauv cov ntshav tseem khaws cia hauv cov khoom ntom ntom.Yog li ntawd, cov khoom ntom ntom yog qhov tseem ceeb rau platelet aggregation.Lub peev xwm tso tawm ADP thiab 5-HT kuj tseem siv rau hauv chaw kho mob los soj ntsuam platelet secretion function.Tsis tas li ntawd, thaj av no tseem muaj mitochondria thiab Lysosome, uas tseem yog qhov chaw tshawb fawb hauv tsev thiab txawv teb chaws xyoo no.Xyoo 2013 Nobel nqi zog hauv Physiology thiab Tshuaj tau muab tsub rau peb tus kws tshawb fawb, James E. Rothman, Randy W. Schekman, thiab Thomas C. S ü dhof, rau kev tshawb pom qhov tsis meej ntawm kev thauj mus los hauv lub cev.Kuj tseem muaj ntau yam tsis paub txog hauv cov metabolism hauv cov tshuaj thiab lub zog hauv platelets los ntawm lub cev hauv lub cev thiab Lysosome.
Qhov tshwj xeeb daim nyias nyias muaj xws li OCS thiab ntom tubular system (DTS).OCS yog ib qho tortuous pipeline system tsim los ntawm qhov chaw ntawm platelets sinking rau sab hauv ntawm platelets, zoo heev ua rau thaj tsam ntawm platelets nyob rau hauv kev sib cuag nrog plasma.Nyob rau tib lub sijhawm, nws yog ib qho channel ntxiv rau ntau yam tshuaj nkag mus rau platelets thiab tso tawm ntau yam ntsiab lus ntawm platelets.Lub raj xa dej DTS tsis txuas nrog lub ntiaj teb sab nraud thiab yog qhov chaw rau kev sib txuas ntawm cov tshuaj hauv cov ntshav.
2. Lub cev muaj nuj nqi ntawm Platelets
Lub luag haujlwm tseem ceeb ntawm cov ntshav platelets yog koom nrog hemostasis thiab thrombosis.Kev ua haujlwm ntawm platelets thaum lub sij hawm physiological hemostasis tuaj yeem faib ua ob theem: thawj hemostasis thiab theem nrab hemostasis.Platelets ua lub luag haujlwm tseem ceeb hauv ob theem ntawm hemostasis, tab sis cov txheej txheem tshwj xeeb uas lawv ua haujlwm tseem txawv.
1) Thawj qhov ua haujlwm hemostatic ntawm platelets
Cov thrombus tsim thaum pib hemostasis feem ntau yog dawb thrombus, thiab ua kom muaj kev cuam tshuam xws li platelet adhesion, deformation, tso tawm, thiab sib sau ua ke yog cov txheej txheem tseem ceeb hauv cov txheej txheem hemostasis thawj zaug.
I. Platelet adhesion cov tshuaj tiv thaiv
Lub adhesion ntawm platelets thiab non platelet nto yog hu ua platelet adhesion, uas yog thawj kauj ruam hauv kev koom tes hauv cov tshuaj tiv thaiv hemostatic tom qab vascular puas tsuaj thiab ib kauj ruam tseem ceeb hauv cov kab mob thrombosis.Tom qab raug mob vascular, platelets ntws los ntawm cov hlab ntsha no tau qhib los ntawm cov ntaub so ntswg hauv qab vascular endothelium thiab tam sim ntawd ua raws li cov collagen fibers ntawm qhov chaw raug mob.Thaum 10 feeb, cov platelets tso hauv zos tau mus txog lawv cov nqi siab tshaj plaws, tsim cov ntshav dawb.
Lub ntsiab tseem ceeb ntawm cov txheej txheem ntawm platelet adhesion muaj xws li platelet membrane glycoprotein Ⅰ (GP Ⅰ), von Willebrand factor (vW factor) thiab collagen hauv cov ntaub so ntswg subendothelial.Cov hom collagen tseem ceeb ntawm cov phab ntsa vascular yog hom I, III, IV, V, VI, thiab VII, ntawm cov hom I, III, thiab IV collagen yog qhov tseem ceeb tshaj plaws rau cov txheej txheem platelet adhesion hauv cov dej ntws.Lub vW yam yog ib tug choj uas txuas cov adhesion ntawm platelets rau hom I, III, thiab IV collagen, thiab glycoprotein tshwj xeeb receptor GP Ib ntawm platelet membrane yog qhov chaw tseem ceeb rau platelet collagen khi.Tsis tas li ntawd, glycoproteins GP IIb / IIIa, GP Ia / IIa, GP IV, CD36, thiab CD31 ntawm platelet daim nyias nyias kuj koom rau hauv adhesion rau collagen.
II.Platelet aggregation cov tshuaj tiv thaiv
Qhov tshwm sim ntawm platelets adhering rau ib leeg yog hu ua aggregation.Cov tshuaj tiv thaiv aggregation tshwm sim nrog cov tshuaj tiv thaiv adhesion.Nyob rau hauv lub xub ntiag ntawm Ca2+, platelet membrane glycoprotein GPIIb/IIIa thiab fibrinogen aggregate dispersed platelets ua ke.Platelet aggregation tuaj yeem raug ntxias los ntawm ob txoj kev sib txawv, ib qho yog ntau yam tshuaj inducers, thiab lwm yam yog tshwm sim los ntawm kev ntxhov siab nyob rau hauv cov dej ntws.Thaum pib ntawm kev sib sau ua ke, platelets hloov pauv los ntawm cov duab disk mus rau ib lub duab kheej kheej thiab protrude ib co pseudo taw uas zoo li cov pos me me;Nyob rau tib lub sijhawm, platelet degranulation yog hais txog kev tso tawm cov tshuaj nquag xws li ADP thiab 5-HT uas tau khaws cia hauv cov khoom ntom ntom.Kev tso tawm ntawm ADP, 5-HT thiab kev tsim tawm ntawm qee qhov Prostaglandin tseem ceeb heev rau kev sib sau ua ke.
ADP yog cov khoom tseem ceeb tshaj plaws rau platelet aggregation, tshwj xeeb tshaj yog cov endogenous ADP tso tawm los ntawm platelets.Ntxiv ib qho me me ntawm ADP (concentration ntawm 0.9) rau platelet suspension μ Hauv qab mol / L), tuaj yeem ua rau platelet aggregation sai, tab sis sai sai depolymerize;Yog tias cov koob tshuaj nruab nrab ntawm ADP (1.0) tau ntxiv μ Nyob ib ncig ntawm mol / L, qhov thib ob irreversible aggregation theem tshwm sim sai tom qab kawg ntawm thawj aggregation theem thiab depolymerization theem, uas yog tshwm sim los ntawm endogenous ADP tso tawm los ntawm platelets;Yog tias ADP ntau ntxiv, nws sai sai ua rau kev sib sau ua ke tsis zoo, uas ncaj qha nkag mus rau theem thib ob ntawm kev sib sau.Ntxiv cov koob tshuaj sib txawv ntawm thrombin rau platelet suspension tuaj yeem ua rau platelet aggregation;Thiab zoo ib yam li ADP, raws li cov koob tshuaj maj mam nce, kev rov qab sib sau ua ke tuaj yeem pom los ntawm tsuas yog thawj theem mus rau qhov tshwm sim ntawm ob theem ntawm kev sib sau, thiab tom qab ntawd ncaj qha mus rau theem thib ob ntawm kev sib sau.Vim tias thaiv kev tso tawm ntawm endogenous ADP nrog adenosine tuaj yeem cuam tshuam platelet aggregation los ntawm thrombin, nws qhia tias cov nyhuv ntawm thrombin tuaj yeem tshwm sim los ntawm kev khi ntawm thrombin rau thrombin receptors ntawm platelet cell membrane, ua rau kev tso tawm ntawm endogenous ADP.Qhov sib ntxiv ntawm collagen kuj tuaj yeem ua rau platelet aggregation nyob rau hauv kev ncua, tab sis tsuas yog irreversible aggregation nyob rau hauv lub thib ob theem feem ntau ntseeg tau los ntawm endogenous tso tawm ntawm ADP los ntawm collagen.Cov tshuaj uas feem ntau tuaj yeem ua rau platelet aggregation tuaj yeem txo cAMP hauv platelets, thaum cov uas inhibit platelet aggregation nce cAMP.Yog li, tam sim no nws ntseeg tau tias qhov txo qis hauv cAMP tuaj yeem ua rau muaj kev nce hauv Ca2 + hauv platelets, txhawb kev tso tawm ntawm endogenous ADP.ADP ua rau platelet aggregation, uas yuav tsum muaj Ca2 + thiab fibrinogen, nrog rau kev siv zog.
Lub luag haujlwm ntawm platelet Prostaglandin Lub phospholipid ntawm platelet plasma membrane muaj Arachidonic acid, thiab platelet cell muaj Phosphatidic acid A2.Thaum platelets tau qhib rau saum npoo, Phospholipase A2 kuj tau qhib.Nyob rau hauv catalysis ntawm Phospholipase A2, Arachidonic acid yog cais los ntawm phospholipids nyob rau hauv lub plasma membrane.Arachidonic acid tuaj yeem tsim ntau ntau ntawm TXA2 nyob rau hauv catalysis ntawm platelet cyclooxygenase thiab Thromboxane synthase.TXA2 txo cAMP hauv platelets, ua rau muaj zog platelet aggregation thiab vasoconstriction nyhuv.TXA2 kuj tsis ruaj khov, yog li nws hloov pauv mus rau TXB2 tsis muaj zog.Tsis tas li ntawd, ib txwm vascular endothelial hlwb muaj prostacyclin synthase, uas tuaj yeem ua rau kev tsim cov prostacyclin (PGI2) los ntawm platelets.PGI2 tuaj yeem nce cAMP hauv platelets, yog li nws muaj zog inhibitory nyhuv ntawm platelet aggregation thiab Vasoconstriction.
Adrenaline tuaj yeem dhau los ntawm α 2. Kev sib kho ntawm Adrenergic receptor tuaj yeem ua rau biphasic platelet aggregation, nrog rau cov concentration ntawm (0.1 ~ 10) μ Mol / L.Thrombin ntawm qis concentrations (<0.1 μ Ntawm mol / L, thawj theem aggregation ntawm platelets feem ntau yog tshwm sim los ntawm PAR1; Nyob rau hauv high concentrations (0.1-0.3) μ Ntawm mol / L, theem ob aggregation yuav induced los ntawm PAR1 thiab PAR4. Muaj zog inducers ntawm platelet aggregation kuj muaj xws li platelet activating factor (PAF), collagen, vW factor, 5-HT, thiab lwm yam. Platelet aggregation kuj tuaj yeem cuam tshuam ncaj qha los ntawm kev siv tshuab tsis muaj inducer. atherosclerosis.
III.Platelet tso tawm cov tshuaj tiv thaiv
Thaum platelets raug rau physiological stimulation, lawv tau khaws cia nyob rau hauv ntom particles α Qhov tshwm sim ntawm ntau yam khoom nyob rau hauv hais thiab lysosomes raug ntiab tawm ntawm lub hlwb yog hu ua ib tug tso tawm cov tshuaj tiv thaiv.Kev ua haujlwm ntawm cov platelets feem ntau yog ua tiav los ntawm cov teebmeem lom neeg ntawm cov tshuaj tsim los yog tso tawm thaum lub sijhawm tso tawm cov tshuaj tiv thaiv.Yuav luag tag nrho cov inducers uas ua rau platelet aggregation tuaj yeem ua rau tso tawm cov tshuaj tiv thaiv.Kev tso tawm cov tshuaj tiv thaiv feem ntau tshwm sim tom qab thawj theem sib sau ua ke ntawm platelets, thiab cov tshuaj tso tawm los ntawm kev tso tawm cov tshuaj tiv thaiv induces theem ob aggregation.Cov inducers uas ua rau tso tawm cov tshuaj tiv thaiv tuaj yeem muab faib ua:
i.Tsis muaj zog inducer: ADP, adrenaline, Norepinephrine, vasopressin, 5-HT.
ii.Medium inducers: TXA2, PAF.
iii.Muaj zog inducers: thrombin, pancreatic enzyme, collagen.
2) Lub luag haujlwm ntawm platelets hauv cov ntshav coagulation
Platelets feem ntau koom nrog ntau yam coagulation cov tshuaj tiv thaiv los ntawm phospholipids thiab daim nyias nyias glycoproteins, suav nrog adsorption thiab ua kom cov coagulation yam (factors IX, XI, thiab XII), tsim coagulation txhawb complexes ntawm phospholipid daim nyias nyias, thiab txhawb kev tsim prothrombin.
Cov plasma membrane ntawm cov platelets khi rau ntau yam coagulation yam, xws li fibrinogen, factor V, factor XI, factor XIII, thiab lwm yam. α Cov khoom kuj muaj fibrinogen, factor XIII, thiab qee cov platelet factor (PF), ntawm cov PF2. thiab PF3 yog ob qho tib si txhawb cov ntshav coagulation.PF4 tuaj yeem neutralize heparin, thaum PF6 inhibits fibrinolysis.Thaum platelets tau qhib rau saum npoo, lawv tuaj yeem ua kom cov txheej txheem ua kom lub ntsej muag ntawm coagulation yam XII thiab XI.Lub phospholipid nto (PF3) muab los ntawm platelets yog kwv yees kom ua kom lub zog ntawm prothrombin los ntawm 20000 zaug.Tom qab txuas yam Xa thiab V rau saum npoo ntawm cov phospholipid no, lawv tuaj yeem tiv thaiv los ntawm inhibitory cuam tshuam ntawm antithrombin III thiab heparin.
Thaum platelets sib sau ua ib hemostatic thrombus, cov txheej txheem coagulation twb tshwm sim hauv zos, thiab platelets tau nthuav tawm ntau qhov chaw ntawm phospholipid, muab cov xwm txheej zoo heev rau kev ua kom muaj X thiab prothrombin.Thaum platelets raug txhawb los ntawm collagen, thrombin lossis kaolin, Sphingomyelin thiab Phosphatidylcholine nyob rau sab nraud ntawm platelet membrane tig nrog phosphatidyl Ethanolamine thiab phosphatidylserine nyob rau sab hauv, ua rau muaj kev nce ntawm phosphatidyl Ethanolamine thiab phosphatidylserine nyob rau saum npoo ntawm daim nyias nyias.Cov pawg phosphatidyl saum toj no tig mus rau saum npoo ntawm platelets koom nrog tsim cov vesicles ntawm daim nyias nyias thaum lub sij hawm ua kom platelet.Cov vesicles tshem tawm thiab nkag mus rau hauv cov ntshav ncig los tsim microcapsules.Cov vesicles thiab microcapsules yog nplua nuj nyob rau hauv phosphatidylserine, uas pab nyob rau hauv lub sib dhos thiab ua kom cov prothrombin thiab koom nyob rau hauv cov txheej txheem ntawm kev txhawb cov ntshav coagulation.
Tom qab platelet aggregation, nws α Kev tso tawm ntawm ntau yam platelet yam hauv cov khoom txhawb kev tsim thiab nce cov ntshav fibers, thiab ntxiab lwm cov ntshav los tsim cov ntshav txhaws.Yog li ntawd, txawm tias platelets maj mam disintegrate, hemostatic emboli tseem tuaj yeem nce ntxiv.Cov platelets sab laug hauv cov ntshav txhaws muaj pseudopodia uas txuas mus rau hauv cov ntshav fiber ntau.Cov proteins contractile nyob rau hauv cov ntawv cog lus platelets, ua rau cov ntshav txhaws rov qab, nyem tawm cov ntshav thiab dhau los ua cov khoom hemostatic ntsaws, khov kho qhov sib txawv vascular.
Thaum ua kom platelets thiab coagulation system ntawm qhov chaw, nws kuj activates lub fibrinolytic system.Plasmin thiab nws cov activator muaj nyob rau hauv platelets yuav raug tso tawm.Kev tso tawm serotonin los ntawm cov ntshav fibers thiab platelets tuaj yeem ua rau cov hlwb endothelial tso tawm cov activators.Txawm li cas los xij, vim tias platelets tawg thiab tso tawm PF6 thiab lwm yam tshuaj uas inhibit proteases, lawv tsis cuam tshuam los ntawm kev ua haujlwm fibrinolytic thaum tsim cov ntshav txhaws.
(Cov ntsiab lus ntawm tsab xov xwm no tau luam tawm dua, thiab peb tsis muab ib qho kev qhia lossis kev lees paub rau qhov raug, kev ntseeg tau lossis ua tiav ntawm cov ntsiab lus muaj nyob rau hauv tsab xov xwm no, thiab tsis muaj lub luag haujlwm rau cov kev xav ntawm tsab xov xwm no, thov nkag siab.)
Post lub sij hawm: Jun-13-2023