Lub paj hlwb ntawm tib neeg thiab vertebrates muaj ib qho kev tsim qauv thiab yog sawv cev los ntawm lub hauv paus - lub hlwb thiab qaum qaum, nrog rau cov seem peripheral - paj hlwb nthuav tawm ntawm lub hauv nruab nrog cev, uas yog cov txheej txheem ntawm cov hlab ntsha. cells - neurons.
Lawv cov kev sib xyaw ua ke tsim cov ntaub so ntswg, lub luag haujlwm tseem ceeb uas yog excitability thiab conductivity. Cov khoom no tau piav qhia feem ntau los ntawm cov yam ntxwv ntawm lub plhaub ntawm cov neurons thiab lawv cov txheej txheem, suav nrog cov khoom hu ua myelin. Hauv tsab xov xwm no, peb yuav txiav txim siab txog cov qauv thiab kev ua haujlwm ntawm qhov sib xyaw no, nrog rau nrhiav txoj hauv kev los kho nws.
Vim li cas neurocytes thiab lawv cov txheej txheem npog nrog myelin
Nws tsis yog qhov xwm txheej uas dendrites thiab axons muaj txheej tiv thaiv uas muaj cov protein-lipid complexes. Qhov tseeb yog tias excitation yog txheej txheem biophysical, uas yog raws li cov hluav taws xob tsis muaj zog impulses. Yog tias cov hluav taws xob tam sim no ntws los ntawm cov hlau, tom qab ntawd yuav tsum tau them nrog cov khoom siv insulating txhawm rau txo qhov tawg ntawm hluav taws xob impulses thiab tiv thaiv.txo tam sim no. Lub myelin sheath ua haujlwm tib yam hauv cov paj hlwb. Tsis tas li ntawd, nws yog kev txhawb nqa thiab tseem muab lub zog rau cov fiber ntau.
tshuaj muaj pes tsawg leeg ntawm myelin
Zoo li feem ntau cov cell membranes, nws muaj lipoprotein xwm. Ntxiv mus, cov roj cov ntsiab lus ntawm no yog siab heev - mus txog 75%, thiab cov proteins - mus txog 25%. Myelin kuj muaj me me ntawm glycolipids thiab glycoproteins. Nws cov tshuaj muaj pes tsawg leeg sib txawv hauv cov leeg txha caj qaum thiab cranial qab haus huv.
Cov qub muaj cov ntsiab lus siab ntawm phospholipids - txog li 45%, thiab tus so yog cov roj cholesterol thiab cerebrosides. Demyelination (uas yog, hloov myelin nrog lwm cov tshuaj hauv cov hlab ntsha) ua rau muaj kab mob autoimmune hnyav xws li ntau yam sclerosis.
Los ntawm kev pom tshuaj lom neeg, cov txheej txheem no yuav zoo li no: myelin sheath ntawm cov paj hlwb hloov nws cov qauv, uas tau tshwm sim feem ntau hauv qhov txo qis hauv feem pua ntawm lipids txheeb ze rau cov protein. Tsis tas li ntawd, tus nqi ntawm cov cholesterol txo qis thiab cov ntsiab lus dej nce ntxiv. Thiab tag nrho cov no ua rau kev hloov maj mam hloov ntawm myelin uas muaj oligodendrocytes lossis Schwann hlwb nrog cov macrophages, astrocytes thiab cov kua nruab nrog cev.
Qhov tshwm sim ntawm cov kev hloov pauv biochemical yuav ua rau lub peev xwm ntawm axons ua kom muaj kev zoo siab mus txog qhov ua tiav ntawm cov hlab ntsha impulses.
Txhim kho cov hlwb neuroglial
Raws li peb tau hais lawm, myelin sheath ntawm dendrites thiab axons yog tsim los ntawm tshwj xeebCov qauv tsim los ntawm cov qib qis ntawm permeability rau sodium thiab calcium ions, thiab yog li ntawd tsuas yog muaj peev xwm so xwb (lawv tsis tuaj yeem ua cov paj hlwb thiab ua haujlwm hluav taws xob hluav taws xob).
Cov qauv no hu ua glial cells. Cov no suav nrog:
- oligodendrocytes;
- fibrous astrocytes;
- ependymal cells;
- plasmic astrocytes.
Tag nrho cov ntawm lawv yog tsim los ntawm txheej txheej ntawm lub embryo - ectoderm thiab muaj ib lub npe - macroglia. Lub glia ntawm lub sympathetic, parasympathetic thiab somatic qab haus huv yog sawv cev los ntawm Schwann hlwb (neurolemmocytes).
qauv thiab kev ua haujlwm ntawm oligodendrocytes
Lawv yog ib feem ntawm lub paj hlwb hauv nruab nrab thiab yog cov hlwb macroglial. Txij li thaum myelin yog cov qauv ntawm cov protein-lipid, nws pab ua kom nrawm nrawm. Cov hlwb lawv tus kheej tsim ib txheej hluav taws xob insulating ntawm cov paj hlwb nyob rau hauv lub hlwb thiab tus txha caj qaum, tsim nyob rau hauv lub sij hawm ntawm intrauterine txoj kev loj hlob. Lawv cov txheej txheem qhwv cov neurons, nrog rau dendrites thiab axons, nyob rau hauv cov quav ntawm lawv cov plasmalemma. Nws hloov tawm tias myelin yog cov khoom siv hluav taws xob tseem ceeb uas cuam tshuam cov hlab ntsha ntawm cov hlab ntsha sib xyaw.
Schwann hlwb thiab lawv cov yam ntxwv
Lub myelin sheath ntawm cov hlab ntsha ntawm lub peripheral system yog tsim los ntawm neurolemmocytes (Schwann hlwb). Lawv qhov txawv feature yog tias lawv muaj peev xwm tsim ib tug tiv thaiv sheath ntawm ib tug axon, thiab tsis tuaj yeem tsim cov txheej txheem zoo li no.muaj nyob rau hauv oligodendrocytes.
Nruab nrab ntawm Schwann hlwb ntawm qhov deb ntawm 1-2 hli muaj thaj chaw uas tsis muaj myelin, lub npe hu ua Ranvier. Los ntawm lawv, hluav taws xob impulses yog nqa tawm spasmodically nyob rau hauv lub axon.
Lemmocytes muaj peev xwm kho cov paj hlwb, thiab tseem ua haujlwm trophic. Raws li qhov tshwm sim ntawm caj ces aberrations, lemmocyte membrane hlwb pib tsis tswj mitotic faib thiab loj hlob, vim hais tias ntawm cov qog - schwannomas (neurinomas) tsim nyob rau hauv ntau qhov chaw ntawm lub paj hlwb.
Lub luag haujlwm ntawm microglia hauv kev puas tsuaj ntawm cov qauv myelin
Microglia yog macrophages muaj peev xwm ntawm phagocytosis thiab muaj peev xwm paub txog ntau yam kab mob - antigens. Ua tsaug rau cov membrane receptors, cov hlwb glial no tsim cov enzymes - proteases, nrog rau cytokines, xws li interleukin 1. Nws yog tus neeg nruab nrab ntawm cov txheej txheem inflammatory thiab tiv thaiv kab mob.
Lub myelin sheath, uas nws lub luag haujlwm yog cais tawm lub tog raj kheej axial thiab txhim kho kev ua haujlwm ntawm cov hlab ntsha impulse, tuaj yeem raug puas los ntawm interleukin. Raws li qhov tshwm sim, cov hlab ntsha yog "liab qab" thiab qhov nrawm ntawm kev ua kom zoo siab tau txo qis.
Ntxiv mus, cytokines, los ntawm activating receptors, provoke ntau thauj cov calcium ions mus rau hauv lub cev ntawm cov neuron. Proteases thiab phospholipases pib zom cov organelles thiab cov txheej txheem ntawm paj hlwb, uas ua rau apoptosis - tuag ntawm cov qauv no.
Nws tawg, tawg mus rau hauv cov khoom uas tau noj los ntawm macrophages. Qhov tshwm sim no hu uaexcitotoxicity. Nws ua rau degeneration ntawm neurons thiab lawv qhov kawg, ua rau cov kab mob xws li Alzheimer's thiab Parkinson's.
Pulp paj fibers
Yog tias cov txheej txheem ntawm cov neurons - dendrites thiab axons, tau them nrog myelin sheath, ces lawv raug hu ua pulpy thiab innervate cov leeg pob txha, nkag mus rau hauv somatic department ntawm lub paj hlwb peripheral. Unmyelinated fibers tsim lub paj hlwb autonomic thiab innervate hauv nruab nrog cev.
Cov txheej txheem pulpy muaj ib txoj kab uas loj dua li cov uas tsis yog nqaij tawv, thiab tsim raws li hauv qab no: axons khoov cov plasma membrane ntawm glial hlwb thiab tsim linear mesaxons. Tom qab ntawd lawv elongate thiab Schwann hlwb pheej rov qhwv ib ncig ntawm lub axon, tsim concentric txheej. Lub cytoplasm thiab nucleus ntawm lemmocyte txav mus rau thaj tsam ntawm txheej txheej, uas yog hu ua neurilemma lossis Schwann membrane.
Cov txheej sab hauv ntawm lemmocyte muaj txheej txheej mesoxon thiab hu ua myelin sheath. Nws qhov tuab ntawm qhov sib txawv ntawm cov hlab ntsha tsis zoo ib yam.
YYuav ua li cas rov qab myelin sheath
Xav txog lub luag haujlwm ntawm microglia hauv cov txheej txheem ntawm cov hlab ntsha demyelination, peb pom tias nyob rau hauv qhov kev txiav txim ntawm macrophages thiab neurotransmitters (piv txwv li, interleukins) myelin raug rhuav tshem, uas ua rau muaj kev puas tsuaj rau cov khoom noj khoom haus ntawm cov neurons thiab. kev cuam tshuam hauv kev xa cov hlab ntsha impulses raws axons.
Qhov no pathology provokes qhov tshwm sim ntawm neurodegenerative phenomena: lub deterioration ntawm kev txawj ntse txheej txheem, ua ntejntawm tag nrho cov cim xeeb thiab kev xav, cov tsos ntawm kev tsis sib haum xeeb ntawm lub cev txav thiab kev txawj tsav tsheb zoo.
Vim li ntawd, qhov kev tsis taus ntawm tus neeg mob tuaj yeem ua tiav, uas tshwm sim los ntawm cov kab mob autoimmune. Yog li ntawd, lo lus nug ntawm yuav ua li cas los kho myelin yog tam sim no mob heev. Cov txheej txheem no suav nrog feem ntau cov khoom noj muaj protein ntau-lipid, kev ua neej zoo, thiab tsis muaj tus cwj pwm phem. Hauv cov kab mob hnyav, kev kho tshuaj yog siv los kho cov kab mob glial uas paub tab - oligodendrocytes.
