Te Mahi a te Whākōkī Pepsin i roto i te Nakunaku Pūmua
He tukanga nui te nakunaku pūmua i roto i te pūnaha nakunaku tangata nā te mea he mahi nui tāna i roto i te hanganga me te whakatikatika kiko, te hanganga whākōkī me te homoni, me te pupuri i te pūnaha ārai mate. Kia taea ai e te tinana te whakamahi i te pūmua kai, me wawahi kia ngawari ake, ko ngā peptide te nuinga, ā, ko ngā waikawa amino te mutunga. Kei roto i tēnei tukanga pakaru he maha ngā whekau me ngā whākōkī nakunaku, ko tētahi o ēnei ko te pepsin. E mōhiotia ana te Pepsin ko te whākōkī matua i roto i te puku, e tīmata ana i te pakaru o te pūmua. Ka matapakihia e tēnei tuhinga te mahi a te pepsin i roto i te nakunaku pūmua, tōna tikanga mahi, ngā āhuatanga tino pai, me tōna whanaungatanga ki ētahi atu whākōkī nakunaku.
He aha te whākōkī pepsin?
He whākōkī nakunaku te Pepsin e hangaia ana e te puku, inā koa e ngā pūtau matua o te pakitara o te puku. Heoi, kāore te pepsin e hangaia tonutia i roto i tōna āhua hohe. Ka hangaia e te puku te pepsin i roto i te āhua kore mahi e kiia nei ko te pepsinogen. He tikanga tiaki tēnei nā te mea ka taea e te pepsin hohe te kino i te kiko o te puku mēnā ka tukuna kia kore e taea te whakahaere. Kātahi ka whakahohehia te Pepsinogen hei pepsin ina pāngia e te taiao waikawa o te puku.
Ka whakaohokia te whakahohenga o te pepsinogen e te waikawa hauwaiora (HCl) i hangaia e ngā pūtau parietal o te puku. Ka whakaitihia e te HCl te pH o te puku, ka hangaia he taiao waikawa nui, he mea tino pai mō te mahi a te pepsin. Hei tāpiri, ka taea hoki e ētahi pepsin kua whakahohehia te āwhina i te whakahohe i ētahi atu pepsinogen mā te tikanga autocatalytic (whakahohe mekameka).
Ko te mahi matua a te pepsin: hei tīmata i te nakunaku pūmua
Ko te mahi matua a te whākōkī pepsin he wawahi i ngā pūmua matatini ki ngā kongakonga iti ake, arā, ko ngā polypeptide me ngā peptide. He mea nui tēnei wāhanga nā te mea ko ngā pūmua e kainga ana mai i te kai ka puta mai i te nuinga o te wā i roto i te āhua o ngā ngota nui, kua whakapikohia (hanganga tuatoru). Kāore e taea te mimiti tika i ēnei ngota nui, matatini e te whekau. Nō reira, me tīmata te nakunaku pūmua i roto i te puku hei whakahaere i te tukatuka atu i roto i te whekau iti.
Ka mahi te Pepsin mā te wawahi i ngā here peptide i roto i ngā pūmua, inā koa ko ērā e uru ana ki ngā waikawa amino kakara pēnei i te phenylalanine, te tyrosine, me te tryptophan. Nō reira, ka pakaru te pūmua roa i te tīmatanga ki ngā mekameka poto ake. Ahakoa kāore anō kia puta he nui o ngā waikawa amino kore utu i te pepsin, ka mahi tēnei whākōkī hei "ara" mō ētahi atu whākōkī, e āhei ai te pakaru pai ake o te pūmua i ngā wāhanga e whai ake nei.
Te whanaungatanga i waenga i te pepsin me te waikawa puku (HCl)
Kāore a Pepsin e mahi takitahi. He tino whakawhirinaki tōna mahi ki te aroaro o te HCl. E toru ngā mahi nui a te waikawa puku e pā tata ana ki te mahi a te pepsin:
1. Whakahohehia te pepsinogen hei pepsin
Ki te kore he āhua waikawa, kāore te pepsinogen e huri hei pepsin, nō reira kāore i te tino pai te nakunaku o te pūmua i roto i te puku.
2. Ka waihanga i te pH tino pai mō te mahi a te pepsin
Ka tino whai hua te mahi a te Pepsin i te pH o te 1,5–2,5, he āhua tino waikawa tēnei. Ina piki te pH ki te tata ki te kūpapa, ka tino heke te mahi a te pepsin.
3. Te whakakore i ngā pūmua kai
Ka āwhina te waikawa puku ki te whakatuwhera i te hanganga pūmua (te whakakorenga matū), kia māmā ake ai te toro atu a te pepsin ki ngā here peptide me te tapahi.
Nō reira, he hoa mahi tahi a HCl me te pepsin ki te tīmata i te nakunaku pūmua i roto i te puku.
Te wāhanga mahi o te pepsin i roto i te puku
I muri i te urunga o te kai ki roto i te puku, ka puta te tukanga pakaru pūmua i roto i ētahi taahiraa:
1. Kai i konatunatua ki te wai o te puku
Mā ngā nekehanga peristaltic o te puku ka hurihia te kai me te HCl me ngā whākōkī.
2. Ka memeha haere ngā pūmua
Ka tīmata te "tuwhera" o te hanganga pūmua matatini nā te taiao waikawa.
3. Ka tapahia e te Pepsin ngā mekameka pūmua
Ka wahia e te Pepsin ngā pūmua ki ngā polypeptides poto ake.
4. Ka hangaia te chyme
Ka huri te kai kua whakaranua, me te kai kua haurua-nakunaku, hei paraoa matotoru e kiia nei ko te chyme, kātahi ka tukuna mārire ki roto i te whekau iti.
Ahakoa ka tīmata te nakunaku pūmua i roto i te puku, ko te nuinga o te tukanga wawahi pūmua hei waikawa amino ka puta i roto i te whekau iti mā te awhina o ngā whākōkī repeure me ngā whākōkī i roto i te pakitara whekau.
Pepsin ki te whakataurite ki ētahi atu whākōkī nakunaku pūmua
Kei roto i te nakunaku pūmua ētahi whākōkī me ā rātou mahi motuhake i ngā wāhi rerekē:
– Pepsin (puku): ka wawahi i ngā pūmua ki ngā peptide iti ake i roto i te taiao waikawa.
– Ko te Trypsin me te chymotrypsin (te repeure, e mahi ana i roto i te whekau iti): ka haere tonu te wawahi i ngā polypeptides ki ngā peptides poto ake.
– Carboxypeptidase (pānihi): ka tapahia ngā waikawa amino mai i te pito o te mekameka peptide.
– Peptidase whekau (tapa paraihe): ka huri i ngā peptide iti hei waikawa amino, hei dipeptides, hei tripeptides rānei hei mimiti.
Mai i tēnei whakataurite, ka kitea he mahi tā te pepsin i te wāhanga tuatahi, ā, ka noho hei tūāpapa mō te wāhanga e whai ake nei kia pai ai te haere.
Ngā āhuatanga e pā ana ki te mahi a te pepsin
Nā te mea e whakawhirinaki ana te pepsin ki te taiao o te puku, he maha ngā āhuatanga ka pā ki tana mahi:
1. Te pH o te puku
He kaha te mahi a te Pepsin i te pH waikawa. Mēnā he teitei rawa te pH (kāore i te nui te waikawa), ka taea te whakakore i te pepsin. Hei tauira, mā te whakamahi roa i ngā rongoā whakaiti waikawa ka taea te whakaiti i te whai huatanga o te nakunaku pūmua i roto i ētahi tāngata, ahakoa he tikanga utu kei te tinana.
2. Te hauora o te pakitara o te puku
Ka heke pea te hanga pepsinogen me te HCl mēnā he mate puku, pērā i te gastritis mau tonu, i ētahi āhuatanga rānei e pā ana ki ngā pūtau whakaputa waikawa.
3. Te nui o te pūmua i roto i te kai
Mā te noho mai o te pūmua ka whakaoho i te whakaputanga o te gastrin, he homoni e whakanui ana i te hanga o te waikawa puku me ngā whākōkī nakunaku, kia pai ake ai te nakunaku o te pūmua.
4. Te wā whakawātea puku
Ki te tere rawa te wehenga atu o te kai i te puku, ka poto ake te wā mahi a te pepsin. I tetahi atu taha, mā te puhoi o te whakawātea i te puku ka nui ake te wā o te pepsin ki te wawahi i ngā pūmua.
He aha te hiranga o te mahi a te pepsin mō te tinana?
He mea nui te mahi a te pepsin, ehara i te mea nā te mea ka wawahi i ngā pūmua anake, engari nā te mea hoki e pā ana te nakunaku pai o te pūmua ki ngā hiahia o te tinana, pēnei i:
– Te wātea o ngā waikawa amino hei hanga me te whakatika i te kiko.
– Te hanganga o ngā whākōkī, ngā homoni me ngā paturopi, ko te nuinga he pūmua.
– Ka tautoko i te tipu me te whakaoranga i muri i te mate, i te whara rānei.
– Ka tautoko i te pākia o te tinana nā te mea ka taea hoki e te pūmua te noho hei puna pūngao ina hiahiatia.
Ina ngoikore te pakaru o te pūmua, ka kore pea te tinana e whiwhi i ngā rauemi mata e tika ana ahakoa te āhua nei he rawaka te kai pūmua.
Whakamutunga
Ko te Pepsin te whākōkī matua i roto i te puku e whai kawenga ana mō te tīmatanga o te nakunaku pūmua. Ka hangaia te Pepsin i roto i te āhua kore mahi (pepsinogen) ā, ka whakahohehia e te waikawa puku (HCl) i te pH tino waikawa. Ko tana mahi he wawahi i ngā pūmua nui ki ngā polypeptides me ngā peptides iti ake, kia pai ake ai te haere tonu o te tukanga nakunaku i roto i te whekau iti e ngā whākōkī pancreatic me te whekau. Nō reira, he mahi nui tā te pepsin ki te whakarite kia tukatukahia ngā pūmua kai hei wāhanga ka taea te mimiti me te whakamahi e te tinana.
Ki te hiahia koe, ka taea hoki e au te tāpiri i tētahi whakaahua o te tukanga nakunaku pūmua (mai i te waha–puku–whekau iti), ka taea rānei e au te hanga i tētahi putanga pūtaiao ake o te tuhinga mō ngā mahi kura/kāreti.
