Passive thauj yog dab tsi? Transmembrane txav ntawm ntau yam macromolecular tebchaw, cellular Cheebtsam, supramolecular hais uas tsis muaj peev xwm nkag mus los ntawm cov channel nyob rau hauv daim nyias nyias, yog nqa tawm los ntawm tshwj xeeb mechanisms, piv txwv li, siv phagocytosis, pinocytosis, exocytosis, hloov los ntawm intercellular qhov chaw. Ntawd yog, kev txav ntawm cov khoom los ntawm daim nyias nyias tuaj yeem tshwm sim los ntawm kev siv ntau yam txheej txheem, uas tau muab faib raws li cov cim qhia ntawm kev koom tes ntawm cov neeg nqa khoom tshwj xeeb hauv lawv, nrog rau kev siv lub zog. Cov kws tshawb fawb faib cov khoom thauj mus rau hauv cov khoom nquag thiab tsis muaj zog.
hom kev thauj khoom loj
Kev thauj mus los yog kev hloov pauv ntawm cov khoom siv los ntawm cov khoom siv roj ntsha raws li gradient (osmotic, concentration, hydrodynamic thiab lwm yam), uas tsis tas yuav siv zog.
Kev thauj mus los yog kev hloov pauv ntawm cov khoom hla ib daim nyias nyias tawm tsam qhov gradient. Qhov twgsiv zog. Kwv yees li 30 - 40% ntawm lub zog uas tau tsim los ntawm cov tshuaj tiv thaiv metabolic hauv tib neeg lub cev yog siv rau kev siv cov khoom thauj khoom. Yog tias peb xav txog kev ua haujlwm ntawm tib neeg lub raum, ces li ntawm 70 - 80% ntawm cov pa oxygen tau siv rau kev thauj mus los.
Kev thauj mus los ntawm cov tshuaj
nws cuam tshuam txog kev hloov pauv ntawm ntau yam khoom los ntawm cov khoom siv roj ntsha nrog ntau hom gradients. Cov gradients no tuaj yeem yog:
- electrochemical muaj peev xwm gradient;
- tshuaj concentration gradient;
- electric teb gradient;
- osmotic siab gradient thiab lwm yam.
Cov txheej txheem ntawm kev siv kev thauj mus los tsis tas yuav tsum muaj kev siv zog. Nws tuaj yeem tshwm sim los ntawm kev yooj yim thiab yooj yim diffusion. Raws li peb paub, diffusion yog ib tug chaotic txav ntawm molecules ntawm ib yam khoom nyob rau hauv ntau yam xov xwm, uas yog vim lub zog ntawm thermal vibrations ntawm ib yam khoom.
Yog hais tias ib qho ntawm cov khoom siv hluav taws xob nruab nrab, ces qhov kev taw qhia uas yuav tshwm sim yog txiav txim siab los ntawm qhov sib txawv ntawm cov concentration ntawm cov khoom uas muaj nyob rau hauv cov xov xwm uas yog sib cais los ntawm daim nyias nyias. Piv txwv li, nyob nruab nrab ntawm qhov chaw ntawm lub cell, nyob rau hauv lub cell thiab sab nraum nws. Yog hais tias cov khoom ntawm cov khoom, nws cov ions muaj ib tug nqi hluav taws xob, ces diffusion yuav nyob ntawm tsis tau tsuas yog nyob rau hauv lub concentration sib txawv, tab sis kuj nyob rau ntawm qhov loj ntawm tus nqi ntawm cov khoom, lub xub ntiag thiab cov tsos mob ntawm tus nqi ntawm ob sab ntawm daim nyias nyias.. Qhov loj ntawm electrochemical gradientyog txiav txim los ntawm algebraic sum ntawm cov hluav taws xob thiab concentration gradients thoob lub membrane.
Yuav ua li cas thauj hla lub membrane?
Kev thauj mus los ntawm daim nyias nyias tuaj yeem ua tau vim muaj cov tshuaj lom neeg cov ntsiab lus gradients, osmotic siab tshwm sim ntawm ntau sab ntawm cov cell membrane lossis hluav taws xob. Piv txwv li, qhov nruab nrab ntawm Na + ions muaj nyob rau hauv cov ntshav plasma yog txog 140 mM / l, thiab nws cov ntsiab lus hauv erythrocytes yog li 12 npaug ntau dua. Xws li gradient, qhia raws li qhov sib txawv ntawm qhov concentration, muaj peev xwm tsim lub zog tsav tsheb uas ua kom muaj kev hloov pauv ntawm sodium molecules rau cov qe ntshav liab los ntawm cov ntshav ntshav.
Nws yuav tsum tau muab sau tseg tias tus nqi ntawm xws li ib tug hloov yog tsawg heev vim lub fact tias lub cell membrane yog yus muaj los ntawm tsawg permeability rau cov ions ntawm cov khoom no. Qhov no daim nyias nyias muaj ntau dua permeability nyob rau hauv relation mus poov tshuaj ions. Lub zog ntawm cellular metabolism tsis yog siv los ua kom tiav cov txheej txheem ntawm kev nthuav dav yooj yim.
Diffusion tus nqi
Kev ua haujlwm thiab kev thauj mus los ntawm cov khoom los ntawm daim nyias nyias yog tus cwj pwm los ntawm tus nqi ntawm kev sib kis. Nws tuaj yeem piav qhia siv qhov sib npaug Fick: dm/dt=-kSΔC/x.
Nyob rau hauv rooj plaub no, dm / dt yog tus nqi ntawm cov khoom uas diffuses nyob rau hauv ib chav tsev ntawm lub sij hawm, thiab k yog tus coefficient ntawm cov txheej txheem diffusion, uas characterizes lub permeability ntawm biomembrane rau cov khoom diffusing. S sib npaug ntawm thaj chaw uas muaj qhov sib txawv, thiab ΔC qhia qhov txawvconcentration ntawm cov tshuaj los ntawm ntau sab ntawm cov kab mob lom, thaum x qhia qhov kev ncua deb ntawm cov ntsiab lus diffusion.
Pom tseeb, cov tshuaj uas sib txawv ib txhij raws cov gradients ntawm cov concentrations thiab hluav taws xob teb yuav yooj yim txav los ntawm daim nyias nyias. Ib qho xwm txheej tseem ceeb rau kev nthuav tawm ntawm cov khoom los ntawm daim nyias nyias yog lub cev lub cev ntawm daim nyias nyias, nws cov permeability rau txhua yam khoom tshwj xeeb.
Vim qhov tseeb tias bilayer ntawm daim nyias nyias yog tsim los ntawm hydrocarbon radicals ntawm phospholipids nrog hydrophobic zog, tshuaj ntawm hydrophobic xwm yooj yim diffuse los ntawm nws. Tshwj xeeb, qhov no siv rau cov tshuaj uas yaj yooj yim hauv lipids, xws li thyroid thiab steroid hormones, nrog rau qee yam tshuaj narcotic.
Mineral ions thiab cov khoom hnyav molecular uas tsis tshua muaj hydrophilic nyob rau hauv cov xwm txheej diffuse los ntawm passive membrane ion raws, uas yog tsim los ntawm channel-forming protein molecules, thiab tej zaum los ntawm daim nyias nyias packing defects ntawm phospholipid molecules uas tshwm sim nyob rau hauv lub cell membrane li. qhov tshwm sim ntawm thermal fluctuation.
Kev thauj mus los hla lub membrane yog txheej txheem nthuav heev. Yog tias cov xwm txheej zoo li qub, ces qhov tseem ceeb ntawm cov khoom tuaj yeem nkag mus rau hauv daim nyias nyias nyias tsuas yog tias lawv tsis yog-polar thiab muaj qhov me me. Txwv tsis pub, kev hloov pauv tshwm sim los ntawm cov khoom thauj cov protein. Cov txheej txheem zoo sib xws nrogcarrier protein tsis yog hu ua diffusion, tab sis thauj khoom los ntawm daim nyias nyias.
Nyob zoo ib tsoom niam txiv kwv tij neej tsas sawv daws
Kev yooj yim diffusion, zoo li yooj yim diffusion, tshwm sim raws qhov concentration gradient ntawm ib yam khoom. Qhov sib txawv tseem ceeb yog qhov tshwj xeeb protein molecule, hu ua tus cab kuj, koom nrog hauv cov txheej txheem ntawm kev hloov tshuaj.
Kev yooj yim diffusion yog ib hom kev hloov pauv hloov pauv ntawm cov molecules ntawm cov khoom los ntawm biomembranes, nqa tawm raws li kev sib xyaw ua ke siv cov cab kuj.
Hloov cov protein ntau
Cov khoom thauj cov protein tuaj yeem ua tau nyob rau hauv ob lub xeev conformational. Piv txwv li, nyob rau hauv lub xeev A, cov protein no tej zaum yuav muaj affinity rau cov khoom uas nws nqa, nws cov chaw khi rau cov khoom yog tig mus rau sab hauv, vim lub pore yog tsim uas qhib rau ib sab ntawm daim nyias nyias.
Tom qab cov protein tau khi rau cov khoom xa mus, nws qhov kev hloov pauv thiab nws dhau mus rau hauv xeev B. Nrog rau qhov kev hloov pauv no, tus neeg nqa khoom poob nws txoj kev sib raug zoo rau cov khoom. Los ntawm kev sib txuas nrog cov cab kuj, nws raug tso tawm thiab txav mus rau lub pore twb nyob rau sab nraud ntawm daim nyias nyias. Tom qab cov tshuaj tau raug xa mus lawm, cov cab kuj hloov pauv hloov pauv hloov pauv, rov qab mus rau lub xeev A. Qhov kev thauj cov khoom hla ntawm daim nyias nyias yog hu ua uniport.
Txoj kev sib kis nrawm nrawm
Cov khoom hnyav molecular xws li qabzib tuaj yeem thauj mus losmembrane los ntawm kev yooj yim diffusion. Xws li kev thauj mus los tuaj yeem tshwm sim los ntawm cov ntshav mus rau lub hlwb, mus rau cov hlwb los ntawm qhov chaw nruab nrab. Tus nqi ntawm kev hloov pauv ntawm cov teeb meem nrog hom diffusion no tuaj yeem ncav cuag 10 8 cov lus los ntawm cov channel hauv ib thib ob.
Raws li peb twb paub lawm, tus nqi ntawm active thiab passive thauj khoom nyob rau hauv yooj yim diffusion yog proportional rau qhov sib txawv nyob rau hauv lub concentration ntawm cov tshuaj nyob rau hauv ob sab ntawm daim nyias nyias. Nyob rau hauv cov ntaub ntawv ntawm kev yooj yim diffusion, tus nqi no nce nyob rau hauv kev faib ua feem rau qhov sib txawv nyob rau hauv lub concentration ntawm cov tshuaj mus txog rau ib tug tej yam nqi siab tshaj. Tshaj li tus nqi no, tus nqi tsis nce ntxiv, txawm tias qhov sib txawv ntawm qhov sib txawv ntawm qhov sib txawv ntawm daim nyias nyias tseem nce ntxiv. Qhov kev ua tiav ntawm qhov siab tshaj plaws tus nqi taw tes hauv cov txheej txheem ntawm kev yooj yim diffusion tuaj yeem piav qhia los ntawm qhov tseeb tias qhov siab tshaj plaws txhais tau hais tias kev koom tes ntawm txhua tus neeg nqa khoom muaj protein ntau hauv cov txheej txheem hloov pauv.
Yuav ua li cas lwm lub tswv yim ua active thiab passive thauj mus los ntawm daim nyias nyias muaj xws li?
Hom kev thauj khoom ntawm cov tshuaj molecules los ntawm cov cell membrane yog qhov tseeb tias cov molecules ntawm tib yam khoom uas nyob rau ntawm ntau sab ntawm cov kab mob lom neeg koom nrog kev sib pauv. Nws yuav tsum tau muab sau tseg tias nrog xws li thauj ntawm cov khoom, lub concentration ntawm molecules ntawm ob sab ntawm daim nyias nyias tsis hloov hlo li.
Ib hom pauv pauv
Ib yam ntawm kev sib pauv diffusion yog kev pauv uasib molecule ntawm ib yam khoom yog pauv rau ob los yog ntau dua molecules ntawm lwm yam khoom. Piv txwv li, ib txoj hauv kev zoo calcium ions raug tshem tawm los ntawm cov leeg nqaij pob txha ntawm lub bronchi thiab cov hlab ntsha los ntawm cov hlab ntsha ntawm lub plawv yog qhov sib pauv rau sodium ions nyob sab nraud ntawm tes. Ib qho sodium ion nyob rau hauv cov ntaub ntawv no yog pauv rau peb calcium ions. Yog li, muaj kev txav ntawm sodium thiab calcium los ntawm daim nyias nyias, uas yog sib cuam tshuam. Hom kev thauj mus los no hla lub cell membrane hu ua antiport. Nws yog nyob rau hauv txoj kev no uas lub cell muaj peev xwm tshem tawm cov calcium ions, uas muaj ntau tshaj. Cov txheej txheem no yog tsim nyog rau du myocytes thiab cardiomyocytes kom so.
Kab lus no tau tshuaj xyuas qhov nquag thiab tsis muaj zog thauj khoom los ntawm daim nyias nyias.
