Kapangidwe ndi Ntchito ya Mapulateleti
Ma platelet, kapena ma platelet a m'magazi, ndi zidutswa zazing'ono za maselo zomwe zimapezeka m'magazi ndipo zimakhudza njira yotsekeka kwa magazi (hemostasis). Ndi gawo lofunika kwambiri la dongosolo la magazi m'thupi la munthu, lomwe limagwira ntchito yofunika kwambiri poletsa kutuluka kwa magazi ndikuyambitsa kuchira kwa mabala. M'nkhaniyi, tifufuza mozama kapangidwe ndi ntchito ya ma platelet, komanso kufunika kwawo pakusunga thanzi la thupi lonse.
Chiyambi ndi Kupanga kwa Mapulateleti
Ma platelet amachokera ku maselo akuluakulu otchedwa megakaryocytes mu fupa la mafupa. Ma megakaryocytes ndi maselo akuluakulu komanso ovuta, okhala ndi mainchesi okwana 100 micrometers. Maselo amenewa amapanga ma platelet mwa kutulutsa zidutswa zazing'ono za cytoplasm yawo m'magazi. Njirayi imayendetsedwa ndi zinthu zosiyanasiyana zokulira ndi mahomoni, kuphatikizapo thrombopoietin, yomwe imalimbikitsa kupanga ndi kukhwima kwa ma megakaryocyte.
Akapangidwa, ma platelet amayendayenda m'magazi kwa masiku pafupifupi 7 mpaka 10 asanawonongeke ndi dongosolo la reticuloendothelial, makamaka mu ndulu ndi chiwindi. Kawirikawiri, kuchuluka kwa ma platelet m'magazi kumayambira pa 150.000 mpaka 450.000 pa microliter iliyonse. Kuchuluka kwa ma platelet ochepa kumatchedwa thrombocytopenia, pomwe kuchuluka kwa ma platelet ambiri kumatchedwa thrombocytosis.
Kapangidwe ka Mapulateleti
Ma platelet ali ndi kapangidwe kake kapadera komanso kovuta ngakhale kuti ndi kakang'ono, kotalika pakati pa ma micrometer awiri ndi atatu m'mimba mwake. Kapangidwe kake kali ndi zigawo zikuluzikulu zingapo:
1. Plasma Membrane: Gawo lakunja la ma platelet, lomwe lili ndi zolandirira mamolekyu osiyanasiyana olumikizirana, kuphatikiza collagen, fibrinogen, ndi zinthu zomwe zimapangitsa kukula. Nembanemba iyi imathandizanso ma glycoprotein omwe amagwira ntchito yofunika kwambiri pakusonkhanitsa ma platelet ndi kumamatira ku makoma a mitsempha yamagazi yovulala .
2. Cytoplasm: Gawo lamkati la platelet lomwe lili ndi ma organelles ndi mapangidwe osiyanasiyana, kuphatikizapo mitochondria, lysosomes, ndi granules. Ma granules awa amakhala ndi alpha granules, omwe ali ndi mapuloteni oundana monga fibrinogen ndi growth factors, ndi dens granules, omwe ali ndi mamolekyu monga ADP ndi calcium omwe amagwira ntchito poyambitsa ma platelet.
3. Cytoskeleton: Ulalo wa mapuloteni opangidwa mkati mwa ma platelet omwe amapereka mawonekedwe ndi chithandizo cha makina. Zinthu zazikulu za cytoskeleton iyi ndi monga actin ndi microtubules, zomwe zimathandiza ma platelet kusintha mawonekedwe awo panthawi yogwira ntchito komanso kusonkhana.
4. Dongosolo Lotseguka la Njira ndi Dongosolo Lodzaza la Ma Tubular: Kapangidwe ka nembanemba yamkati yomwe imagwira ntchito yosungira ndi kutulutsa mamolekyulu olumikizirana. Dongosolo lotseguka la njira limalumikizana ndi kunja kwa selo ndipo limathandiza kutulutsa zomwe zili mu granule, pomwe dongosolo lodzaza la ma tubular limagwira ntchito yosungira calcium ndikuwongolera kuchuluka kwa calcium mkati mwa maselo.
Ntchito ya Mapulateleti
Ma platelet ali ndi ntchito zingapo zazikulu zokhudzana ndi hemostasis ndi machiritso a mabala :
1. Kupanga Pulagi ya Mapulateleti
Pamene mtsempha wamagazi wavulala, collagen ndi tissue factor kuchokera ku extracellular matrix yomwe yawonekera imayambitsa nthawi yomweyo ma platelets. Ma platelets oyambitsidwa amasintha mawonekedwe, amakhala omata, ndikumamatira ku khoma la mtsempha wovulala. Amayambanso kutulutsa zomwe zili mu granules zawo, kuphatikizapo coagulation factors ndi mamolekyu ena olumikizirana omwe amakopa ma platelets ambiri pamalo ovulala.
Njira imeneyi imapangitsa kuti magazi azituluka m'magazi pang'ono, zomwe zimapangitsa kuti magazi azituluka m'magazi pang'ono. Iyi ndi njira yoyamba yochepetsera magazi m'thupi, yomwe imaletsa kutaya magazi ambiri mpaka magazi atayamba kuuma bwino.
2. Kutulutsidwa kwa Othandizira Mankhwala
Akayamba kugwira ntchito, ma platelet amatulutsa mankhwala osiyanasiyana ochokera ku ma granules awo. Ma alpha granules amatulutsa mapuloteni monga fibrinogen, platelet growth factor (PDGF), coagulation factors, kininogen, ndi vWf (von Willebrand factor), zomwe zimathandiza kuti ma platelet agwirizane komanso kuti ma platelet azikhazikika. Ma granules a dens amatulutsa mamolekyu ang'onoang'ono monga ADP, ATP, serotonin, ndi calcium, omwe amagwira ntchito yochepetsa magazi, kukopa ma platelet ambiri pamalo omwe avulala, komanso kuchititsa kuti ma platelet ayambe kugwira ntchito.
Mwachitsanzo, ADP imamangirira ku cholandirira cha P2Y12 pamwamba pa ma platelet, zomwe zimapangitsa kuti mawonekedwe a ma platelet asinthe, kuwonjezera mphamvu yawo pa fibrinogen, ndikulimbitsa mgwirizano pakati pa ma platelet, zomwe zimapangitsa kuti kusonkhana kwamphamvu kukhale kolimba. Calcium imagwira ntchito yofunika kwambiri panjira zosiyanasiyana zotsekeka, zomwe zimathandiza kupanga ma enzyme complexes pamwamba pa ma platelet.
3. Kutsekeka kwa Fibrin ndi Kupangika kwa Fibrin
Kuwonjezera pa kupanga pulagi ya platelet ndi kutulutsa ma mediator, ma platelet amalimbikitsanso kupanga fibrin, puloteni yomwe imalimbitsa ndikukhazikitsa pulagi ya platelet. Ma platelet oyambitsidwa amapereka malo omwe amathandizira kuyanjana kwa zinthu zozungulira m'njira zamkati ndi zakunja, zomwe pamapeto pake zimapangitsa kuti fibrinogen yosungunuka ikhale fibrin yosasungunuka. Kenako fibrin imapanga netiweki yomwe imakola maselo ofiira amagazi ndi maselo ena m'magazi, ndikupanga magazi kuundana okhazikika.
4. Kuchiritsa Mabala
Kuwonjezera pa ntchito yawo pa hemostasis, ma platelet amathandizanso pakuchira kwa bala. Zinthu zomwe zimakula zomwe zimatulutsidwa ndi ma platelet, monga PDGF, vascular endothelial growth factor (VEGF), ndi transforming growth factor-beta (TGF-β), zimapangitsa kuti maselo azichulukana komanso kusamuka kupita kumalo ovulala, kuphatikizapo ma fibroblast, ma endothelial cell, ndi ma epithelial cell. Njira imeneyi imathandiza kupanga minofu yatsopano ndi mitsempha yamagazi (angiogenesis), yomwe ndi yofunika kwambiri kuti mabala achire bwino.
Matenda a Platelet
Kulephera kugwira ntchito bwino kapena kusagwira bwino ntchito kwa kuchuluka kwa ma platelet m'magazi kungayambitse mavuto osiyanasiyana azaumoyo:
– Thrombocytopenia: Kuchuluka kwa ma platelet m'magazi kungayambitse kutuluka magazi ambiri komwe kumakhala kovuta kuletsa. Vutoli lingayambitsidwe ndi zinthu zosiyanasiyana, kuphatikizapo matenda odziteteza ku matenda, matenda opatsirana, kapena zotsatirapo zoyipa za mankhwala.
– Thrombocytosis: Kuchuluka kwa ma platelet m'magazi kungapangitse kuti magazi aziundana, zomwe zingayambitse sitiroko kapena matenda a mtima. Zomwe zimayambitsa matendawa zikuphatikizapo matenda a myeloproliferative, zomwe zimachitika chifukwa cha matenda kapena kutupa, kapena matenda osatha.
– Kulephera kwa Mapulateleti: Mapulateleti omwe sagwira ntchito bwino, ngakhale atakhala kuti ndi ambiri, angayambitsenso mavuto otuluka magazi, monga matenda ena a majini kapena chifukwa cha mankhwala enaake.
Mapeto
Ma platelet amagwira ntchito yofunika kwambiri mu dongosolo la magazi ndi hemostasis. Ndi gawo lofunikira kwambiri pa chitetezo cha thupi ku kutuluka magazi ndipo ali ndi ntchito zina zowonjezera pakuchiritsa mabala. Kumvetsetsa bwino ma platelet, omwe ali abwinobwino komanso omwe ali ndi matenda, ndikofunikira kwambiri popewa ndi kuchiza matenda osiyanasiyana a magazi. Kafukufuku akupitiliza kufufuza mbali zosiyanasiyana za ma platelet, kuphatikizapo kuthekera kwawo pa chithandizo chamankhwala ndi njira zamankhwala.
