Udindo wa Thymus Gland mu Chitetezo cha Mthupi
Thymus gland ndi chiwalo chofunikira kwambiri m'thupi la munthu, ngakhale nthawi zambiri sichidziwika bwino kuposa ziwalo zina monga ndulu kapena mafupa. Thymus imagwira ntchito yofunika kwambiri popanga ndi kusamalira maselo oteteza thupi, zomwe zimathandiza kuti ateteze thupi ku matenda popanda kuukira minofu yake. Kumvetsetsa thymus kumatithandiza kumvetsetsa momwe chitetezo cha thupi chimakulira kuyambira ali aang'ono, chifukwa chake chitetezo cha mthupi chimasintha ndi ukalamba, komanso zomwe zimachitika ntchito ya thymus ikasokonekera.
Malo ndi makhalidwe a thymus gland
Thymus ili m'chifuwa chapamwamba, kumbuyo kwa fupa la m'mawere (sternum) komanso kutsogolo kwa mtima. Kwa ana, imakhala yayikulu komanso yogwira ntchito. Komabe, ikakula, thymus imadutsa mu njira yotchedwa involution, yomwe imaphatikizapo kuchepa ndikusintha minofu yake yogwira ntchito ndi mafuta. Ngakhale kuti imachepa, thymus imasungabe ntchito yake yoteteza thupi, makamaka kudzera mu cholowa cha maselo a T omwe amapangidwa ali aang'ono.
Mu thupi, thymus imakhala ndi ma lobes awiri ndipo imagawidwa m'magawo awiri akuluakulu: cortex (gawo lakunja) ndi medulla (gawo lamkati). Kortex ili ndi maselo ang'onoang'ono a T omwe akukula (thymocytes), pomwe medulla ili ndi maselo a T okhwima komanso kapangidwe kotchedwa Hassall's corpuscles, omwe amaganiziridwa kuti amagwira ntchito pakukhwima ndikuwongolera mayankho a chitetezo chamthupi.
Thymus ngati "sukulu" ya maselo a T
Ntchito yaikulu ya thymus ndikukhala malo okhwima a ma T lymphocytes (ma T cells), omwe ndi amodzi mwa zigawo zofunika kwambiri pa chitetezo chamthupi chosinthika. Ma T cells amachokera ku maselo oyambira mu fupa kenako amasamukira ku thymus kuti akakule. Mu thymus, maselowa amadutsa njira zingapo zosankhira kuti atsimikizire kuti angathe:
1. Kuzindikira ma antigen akunja (monga mavairasi ndi mabakiteriya) molondola.
2. Sichimenyana ndi minofu ya thupi (chimaletsa chitetezo chamthupi).
Njira imeneyi nthawi zambiri imafanana ndi njira yophunzitsira ndi kusankha odwala mozama, monga sukulu ya usilikali kapena sukulu yapadera, chifukwa maselo okhawo omwe amakwaniritsa zofunikira ndi omwe "amamaliza maphunziro awo" ndikutumizidwa ku magazi ndi ziwalo zina za lymphoid.
Kusankha bwino: kuonetsetsa kuti maselo a T amatha kugwira ntchito
Gawo loyamba lofunika kwambiri ndi kusankha bwino. Mu gawo ili, thymus imayesa ngati cholandirira maselo a T (TCR) chingazindikire mamolekyu a MHC (major histocompatibility complex), "mapulatifomu" pamwamba pa maselo a thupi omwe amagwiritsidwa ntchito kuwonetsa zidutswa za antigen. Ngati selo la T silingazindikire MHC konse, limaonedwa kuti ndi lopanda ntchito pa chitetezo cha thupi ndipo limachotsedwa.
Zotsatira za kusankha bwino zimathandizanso kudziwa "ntchito" ya maselo a T: ngati amakhala maselo a CD4 T (maselo a T othandizira) omwe amagwira ntchito yolamulira chitetezo cha mthupi, kapena maselo a CD8 T (maselo a T oopsa) omwe amagwira ntchito yopha maselo omwe ali ndi kachilombo ndi maselo a khansa.
Kusankha kolakwika: kupewa chitetezo chamthupi chokha
Pambuyo posankha bwino, maselo a T amasankhidwa ndi negative. Gawoli cholinga chake ndi kuchotsa maselo a T omwe amazindikira ma antigen amphamvu kwambiri. Ngati maselo a T amalumikizana kwambiri ndi ma antigen a thupi, amatha kuukira ziwalo ndikuyambitsa matenda odziteteza. Thymus imayambitsa kufa kwa maselo a T owopsawa (apoptosis).
Njira imodzi yofunika kwambiri yosankha negative ikuphatikizapo puloteni ya AIRE (autoimmune regulator). AIRE imalola maselo ena mu thymus kuwonetsa ma antigen osiyanasiyana omwe nthawi zambiri amapezeka m'ziwalo zinazake (monga ma antigen ochokera ku chithokomiro, kapamba, kapena khungu). Mwanjira imeneyi, thymus imatha "kuyambitsa" ma self-antigen osiyanasiyana ku maselo a T omwe akukula, potero kuchotsa maselo a T omwe amayankha ma antigen awa pachiyambi.
Kupanga kulekerera kwa chitetezo chamthupi ndi ntchito ya maselo olamulira a T
Kuwonjezera pa kuchotsa maselo owopsa, thymus imathandizanso kukhazikitsa kupirira kwa chitetezo chamthupi, mphamvu ya chitetezo chamthupi yopirira minofu yake. Chimodzi mwa zinthu zofunika kwambiri zomwe thymus imatulutsa ndi maselo a T olamulira (Tregs). Maselo a Treg amagwira ntchito ngati "brake" pa chitetezo chamthupi kuti apewe kuchita zinthu mopitirira muyeso komanso kudziwononga okha. Ma Treg amathandiza kukhalabe olimba, kuchepetsa kutupa kosafunikira, komanso kupewa matenda a autoimmune.
Mwa kuyankhula kwina, thymus sikuti imangopanga maselo ankhondo okha, komanso imapanga maselo oteteza mtendere omwe amaletsa chitetezo cha mthupi kuchita zinthu mwankhanza popanda kulamulira.
Kugwirizana kwa thymus ndi chitetezo chamthupi muubwana
Pa nthawi ya ubwana ndi ubwana, thymus imagwira ntchito kwambiri popanga maselo atsopano a T. Izi ndizofunikira chifukwa ana amafunika kuchuluka kwa maselo a T kuti azindikire matenda osiyanasiyana omwe amakumana nawo koyamba. Chitetezo chosinthika chimakula mwachangu panthawiyi, pamene thupi "limapeza chidziwitso" ndi ma antigen osiyanasiyana achilengedwe, kudzera mu matenda achilengedwe ndi katemera.
Kuchuluka kwa mphamvu ya thymus muunyamata kumafotokozanso chifukwa chake chitetezo cha mthupi cha ana chingapitirize kupanga mitundu yosiyanasiyana ya maselo a T. Kusiyanasiyana kumeneku kumapereka chithandizo chofunikira kwambiri polimbana ndi chiopsezo cha matenda mtsogolo.
Kusinthika kwa thupi ndi kusintha kwa chitetezo chamthupi mu ukalamba
Pamene unyamata ndi ukalamba zikuyandikira, thymus imayamba kuchepa, ndipo kupanga maselo atsopano a T kumachepa. Njira yosinthira iyi ndi imodzi mwa zinthu zomwe zimapangitsa kuti chitetezo cha mthupi mwa okalamba chisamayankhe bwino matenda atsopano. Anthu okalamba amakonda kudalira maselo okumbukira omwe adapangidwa kale, koma kuthekera kwawo kupanga maselo atsopano a T kumachepa.
Motero, okalamba amakhala pachiwopsezo chachikulu cha matenda ena opatsirana, momwe amayankhira katemera akhoza kukhala ofooka, ndipo njira yawo yochira ikhoza kukhala yocheperako. Komabe, chitetezo cha mthupi sichisiya kugwira ntchito; chimangosintha, ndi maselo okumbukira ambiri komanso kuchepa kwa mitundu yosiyanasiyana ya maselo a T.
Zotsatira za kusokonekera kwa thymus
Ngati thymus sikukula bwino kapena yawonongeka, zotsatira zake zingakhale zoopsa kwambiri. Matenda ena okhudzana ndi thymus ndi awa:
1. DiGeorge syndrome: matenda obadwa nawo omwe angayambitse kuti thymus isapangidwe bwino, kotero kuti mwana amakhala ndi vuto la T cell ndipo amakhala pachiwopsezo chotenga matenda.
2. Myasthenia gravis: matenda odziteteza okha omwe nthawi zambiri amagwirizanitsidwa ndi thymus yokulirapo (hyperplasia) kapena chotupa cha thymic (thymoma). Ngakhale kuti njira zake ndi zovuta, thymus imaganiziridwa kuti imagwira ntchito pakukula kwa chitetezo chamthupi cholakwika.
3. Thymoma: chotupa mu thymus chomwe chingakhudze chitetezo cha mthupi ndipo nthawi zina chimagwirizanitsidwa ndi chitetezo chamthupi chokha kapena matenda ena a chitetezo chamthupi.
Kumbali ina, kuchotsa thymus (thymectomy) m'mikhalidwe ina kungakhale kothandiza, mwachitsanzo nthawi zina za myasthenia gravis, ngakhale kuti zotsatira zake zimadalira zaka ndi momwe wodwalayo alili.
Thymus m'nkhani yamakono: kafukufuku ndi zotsatira zake pa thanzi
Kafukufuku wamakono akuyang'ana kwambiri momwe angasungire kapena kubwezeretsa ntchito ya thymus, makamaka pankhani ya ukalamba ndi kuchira kwa chitetezo chamthupi pambuyo pa chithandizo cha khansa monga chemotherapy. Njira zingapo zomwe zikuphunziridwa zikuphatikizapo mahomoni, ma cytokines, ndi njira zobwezeretsa. Cholinga chake ndikupititsa patsogolo luso la thupi lopanga maselo atsopano a T kuti chitetezo chamthupi chikhale champhamvu komanso chokhazikika.
Kuphatikiza apo, kumvetsetsa kusankha maselo a T mu thymus kumathandizanso pakupanga njira zochiritsira matenda odziteteza ku matenda a autoimmune ndi ukadaulo wa immunotherapy, kuphatikizapo kuyesetsa kupanga maselo a chitetezo chamthupi kuti alimbane ndi khansa. Ngakhale kafukufuku wambiri akadali kuchitika, thymus ikadali yofunika kwambiri chifukwa cha ntchito yake yayikulu: kupanga maselo a T ogwira ntchito bwino komanso otetezeka.
Mapeto
Thymus gland imagwira ntchito yofunika kwambiri pa chitetezo chamthupi, makamaka ngati malo okhwima ndi kusankha maselo a T. Kudzera mu kusankha kwabwino ndi koipa, thymus imatsimikizira kuti maselo a T amatha kulimbana ndi tizilombo toyambitsa matenda koma osaukira maselo a thupi. Thymus imathandizanso kuti chitetezo chamthupi chizigwira ntchito bwino kudzera mu kupanga maselo a T olamulira. Ngakhale kuti imachepa ndi ukalamba, "chopereka choyambirira" cha thymus popanga mndandanda wa maselo a T chimakhala ndi zotsatira zokhalitsa pa thanzi la chitetezo chamthupi cha munthu. Pomvetsetsa ntchito ya thymus, timazindikira kwambiri kuti chitetezo chamthupi sichimangolimbana ndi matenda okha, komanso chimakhala chokhazikika kuti chitetezo chamthupi chizigwira ntchito bwino.
