Ntawm cov khoom ntawm cov plasma membrane, nws cov kev xaiv permeability yog ib qho tseem ceeb. Ua tsaug rau nws, kev faib tawm ntawm cov kua dej ntawm cov kab mob multicellular rau hauv cov khoom sib txuas yog tsim, nyob rau hauv txhua yam ntawm nws tus kheej muaj pes tsawg leeg ntawm electrolytes thiab organic tshuaj yog tsim. Txhua lub organelle lossis cell framed los ntawm cov plasma membrane nruj nreem cais ib puag ncig ntawm lub cev thiab tswj kev thauj khoom ntawm ob txoj kev.
txhais thiab yam ntxwv
Kev xaiv permeability yog ib qho khoom tshwj xeeb ntawm phospholipid bilayer ntawm daim nyias nyias nrog ion raws ua rau hauv nws cov tuab. Qhov zoo no yog cov yam ntxwv ntawm txhua lub cell, nrog rau cov kab mob membrane: lysosomes, mitochondria, nucleus, Golgi complex, reticulum. Kev xaiv ntawm daim nyias nyias yog nyob ntawm nws cov qauv, uas suav nrog thaj tsam hydrophobic ntawm phospholipids.
Tom qab kev kawmfompholipid bilayer nrog thaj chaw hydrophobic sib ntsib, qhov permeability ntawm dej los ntawm plasmalemma yog txwv. Nws tuaj yeem nkag mus rau sab hauv thiab sab nraud ntawm tes nkaus xwb los ntawm cov channel transmembrane, kev thauj mus los uas yog ua raws li cov cai ntawm osmosis los ntawm kev sib kis. Xaiv permeability rau dej molecules yog tswj los ntawm osmotic siab. Nyob rau hauv cov ntaub ntawv ntawm ib tug nce nyob rau hauv lub concentration ntawm ntsev nyob rau hauv lub cell, dej nkag mus rau hauv cov channel mus rau hauv lub cytoplasm, thiab nyob rau hauv cov ntaub ntawv ntawm ib tug nce nyob rau hauv extracellular osmotic siab, nws rushes mus rau hauv lub intercellular qhov chaw.
Kev thauj mus los
Lub cell membrane cais ob qhov chaw - qhov chaw intercellular nrog lub cytoplasm (los yog kab noj hniav ntawm cov organelle thiab cytoplasm). Thiab ntawm txhua qhov chaw yuav tsum muaj kev sib pauv cov khoom tsis tu ncua. Lub plasmalemma yog tus yam ntxwv los ntawm kev thauj mus los tsis muaj zog.
Cov nyiaj tau los nrog cov nqi hluav taws xob thiab tso cai rau koj thauj khoom los ntawm thaj chaw qis dua mus rau qhov loj dua. Passive thauj yog pub dawb nkag mus rau lipophilic tshuaj mus rau hauv lub cell los ntawm plasmalemma, nrog rau kev hloov ntawm ions los ntawm tshwj xeeb raws los ntawm ib cheeb tsam ntawm siab concentration mus rau ib cheeb tsam nrog ib tug qis dua cov ntsiab lus ntawm tib hom ions.
transmembrane receptors
Kev xaiv permeability ntawm daim nyias nyias rau ions yog tswj hwm los ntawm cov ion tshwj xeeb hauv cov plasmalemma. Rau txhua tus ion, lawv sib txawv thiab tswj kev thauj mus los sai lossis kev thauj mus los qeeb ntawm hydrated ions. Ion channel rau potassium ib txwmqhib, thiab pauv cov poov tshuaj yog nqa tawm nyob ntawm seb lub peev xwm ntawm daim nyias nyias.
Sodium yog tus cwj pwm los ntawm kev muaj ob qho tib si qeeb thiab nrawm. Cov qeeb qeeb ua haujlwm ntawm lub hauv paus ntsiab lus zoo ib yam li cov poov tshuaj, thiab kev ua haujlwm ntawm cov kab nrawm yog ib qho piv txwv ntawm kev thauj mus los uas tshwm sim nrog cov nqi hluav taws xob. Nws yuav siv qhov chaw nyob rau hauv cov ntaub ntawv ntawm kev ua muaj peev xwm tiam, thaum lub siab-siv intracellular influx ntawm sodium ions yog muab los ntawm lub sij hawm luv luv activation ntawm ceev raws, raws li membrane recharge.
Kev xaiv permeability ntawm plasmalemma yog qhov tseem ceeb rau kev thauj cov protein molecules, amino acids, vitamins thiab tseem ceeb cofactors ntawm cell enzyme systems. Cov molecules no yog polar thiab hydrophilic, thiab yog li tsis tuaj yeem nkag mus rau hydrophobic lipid bilayer. Rau lawv txoj kev thauj mus los, muaj cov kab tshwj xeeb hauv cov tuab ntawm daim nyias nyias, uas yog cov glycoproteins nyuaj.
Kev hloov pauv hloov pauv
Txoj kev sib txuas ntawm cov ligands tshwj xeeb rau cov receptors qhib qhov kev nkag ntawm cov tshuaj mus rau hauv lub cell. Rau txhua hom ntawm xws li molecules, nws tus kheej tshwj xeeb cov cab kuj yog tsim rau hauv lub thickness ntawm daim nyias nyias. Qhov no yog txoj kev nruj tshaj plaws thiab tshwj xeeb tshaj plaws ntawm kev teeb tsa cov kev xaiv permeability ntawm lub xov tooj ntawm tes - lav tias tsis muaj cov khoom tsis tsim nyog nyob rau theem no ntawm nws txoj kev loj hlob yuav nkag mus rau hauv cytoplasm.
Cov qauv ntawm cov neeg nqa khoom tshwj xeeb transmembrane yog encoded hauv cov khoom siv caj ces ntawm cov nucleus. Thiab cov txheej txheem ntawm assembling ib tug tshiabcov channel rau kev thauj khoom yog tswj los ntawm lub cell nws tus kheej. Qhov no txhais tau hais tias nyob rau txhua theem ntawm nws qhov sib txawv, nws muaj peev xwm pib los yog nres cov ndlwg ntawm tej yam khoom mus rau hauv nws cytoplasm, nyob ntawm seb lwm yam mob.
Intracellular receptors
Cell thiab membrane organelles muaj kev xaiv permeability vim yog intracellular receptors. Lawv tau tsim los kom tau txais cov cim qhia los ntawm cov tshuaj lipophilic. Tsis zoo li hydrophobic sawv daws yuav, xws li molecules muaj peev xwm integrate mus rau hauv lub lipid bilayer ntawm daim nyias nyias thiab ua luam dej nyob rau hauv nws ntev, tom qab uas lawv nkag mus rau hauv lub cytoplasm thiab hu rau lub intracellular los yog nuclear receptor.
Ib qho piv txwv yog kev nkag mus ntawm cov tshuaj hormones steroid. Lawv dawb do dhau los ntawm cytolemma thiab, tom qab kev sib cuag nrog ib tug tshwj xeeb receptor, qhib los yog suppress ib tug tej yam txuas nyob rau hauv lub metabolic chains. Qhov muaj peev xwm ntawm kev pub dawb ntawm lipophilic tshuaj los ntawm cov ntshav plasma kuj yog ib qho piv txwv ntawm kev xaiv permeability.
Txhua yam lipophilic uas tuaj yeem kov yeej lipid bilayer, yaj hauv nws, muaj cov receptor intracellular. Hydrophilic molecules repel polarized cheeb tsam ntawm daim nyias nyias thiab yog li ntawd yuav tsum tau txuas mus rau lub transmembrane transporter los yog txuas rau saum npoo receptor molecules ntawm daim nyias nyias kom xa cov teeb liab los yog nkag mus rau hauv lub cell.
