Tieu Luan Doc Hoc Moi Truong-16-10-Final

8/8/2019 Tieu Luan Doc Hoc Moi Truong-16-10-Final

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Chuyn : Ma axit GVHD: TS Mai TunAnh

I HC NNGI HC NNG

LP CAO HC CNG NGH MI TRNG

BI TIU LUNBI TIU LUN

C HC MI TRNGChuyn : CC YU T NH HNG N TNH C

GING VIN HNG DN: GS.TS NG KIM CHI

HC VIN THC HIN:

1. TRN TH KIU NGN

2.NGUYN TH YN PHNG

Hc vin thc hin: 1. Nguyn Th Yn Phng2. Trn Th Kiu Ngn 1


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NNG, 10/2010

MC LC

LI M U..................................................................................................................................4

1.1. c cht hc.........................................................................................................................5

1.2. c hc mi trng..............................................................................................................5

1.3. Cht c v tnh c.............................................................................................................6

1.3.1. Cht c.........................................................................................................................61.3.2. Tnh c.........................................................................................................................6

2. Cc yu t nh hng n tnh c.............................................................................................7

2.1. Bn cht ca tc nhn gy c (bn cht ha hc v bn cht l hc ca cht c)............8

2.2. iu kin tip xc...............................................................................................................10

2.3. Loi, gii tnh, tui v cc yu t di truyn ti thi im tip xc................................12

2.4. Tnh trng ca sinh vt ti thi im tip xc....................................................................17

2.5. S c mt ca cc ha cht trong c th sinh vt, trong mi trng v trong thi gian tip

xc..............................................................................................................................................18

2.6. Chp nhn hay thch ng....................................................................................................23

2.7. Cc yu t mi trng v cc yu t khc c th nh hng n kh nng phn ng ca c

th i vi c cht....................................................................................................................28

TI LIU THAM KHO.............................................................................................................30



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DANH MC HNH V BNG

Hnh 1- th biu din tc ng ca CYP i vi loi gm nhm c v ci............................14

Hnh 2- S hot ha khc nhau ca 2- AAF i vi chut c v chut ci................................14

Hnh 3- S chuyn ha ca cht c........................................................................................21

Hnh 4- Mt kiu hot ha enzim................................................................24

Hnh 5- Bin i ti trung tm hot ng ca enzim.....................................................................25

Hnh 6- Men acetycolin estera.......................................................................................................26

Hnh 7 - Cu trc ca pyrithamine v trimethoprim........................................27Hnh 8- Cu trc ca pyrethrin.....................................................................................................27

Hnh 9 - Chuyn ha ca malathion thnh malaoxon....................................................................27

Bng 1- Tnh nhy cm ca mt s loi i vi c cht ty thuc vo gii tnh........................14



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LI M U

Hin nay, cng nghip ha, hin i ha pht trin vi tc nhanh nh v bo th

nhim mi trng ang l vn nn ton cu. Km theo vn nhim l t l c cht pht thi

ra mi trng ngy cng nhiu v vn cha c hng gii quyt tha ng. c hc mi trngang l vn quan tm v nghin cu nc ta v trn ton th gii. Nghin cu v c cht

v nhng yu t nh hng n tnh c gip chng ta phn no hn ch ri ro v sc khe cng

nh gp phn bo v mi ngi trc nhng nguy c nhim bnh t mi trng.



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1. Cc khi nim c bn

1.1. c cht hc

- c cht hc l ngnh khoa hc nghin cu v lng v cht cc tc ng bt li

ca cc tc nhn ha hc, vt l, sinh hc ln h thng sinh vt hc ca sinh vt sng.

- c cht hc l ngnh khoa hc v c cht. L mt ngnh khoa hc c bn v

khoa hc ng dng.

1.2. c hc mi trng

- c hc mi trng v c hc sinh thi trong mi trng rt gn nhau trong i

tng nghin cu v mc ch, c xem nh l ng nht.

- c hc mi trng l mt ngnh nghin cu quan h cc tc nhn c hi trong

mi trng t nhin (ngun gc, kh nng ng dng, s xut hin, o thi, hy dit) v

phng thc hot ng ca chng trong mi trng.

- c hc mi trng nghin cu s bin i, tn lu v tc ng ca tc nhn gy

nhim vn c trong thin nhin v cc tc nhn nhn to nh hng n cc hot

ng sng ca sinh vt trong h sinh thi, cc tc ng c hi n con ngi.

- c hc sinh thi l ngnh khoa hc l ngnh khoa hc quan tm n cc tc ng

c hi ca cc tc nhn ha hc v vt l ln cc c th sng. c bit l tc ng ln cc

qun th v cng ng trong h sinh thi. Cc tc ng bao gm: con ng xm nh p

ca cc tc nhn l ha v cc phn ng gia chng vi mi trng. Mc tiu chnh ca

c hc sinh thi l to ra nhng chun mc ban u thit l p tiu chun cht lng mi

trng, nh gi v d on nng trong mi trng, nguy c cho cc qun th t

nhin (trong c c con ngi) b tc ng mnh bi s nhim mi trng.

C s khc nhau c bn gia c hc mi trng v c hc sinh thi. c hc

thc nghim thng tin hnh th nghim trn ng vt c v v cc s liu dng a

ra cc gii hn an ton ch cho mt mc tiu tip cn, l con ngi. Ngc li, mc

tiu ca c hc sinh thi l bo v ton b sinh quyn, bao gm hng triu loi khc

nhau, c t chc theo qun th, cng ng, cc h sinh thi c lin h vi nhau l bo

v sc khe con ngi trong cng ng mc tng c th m bo tn cu trc vchc nng ca cc h sinh thi.



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1.3. Cht c v tnh c

1.3.1. Cht c

- Cht c l bt c loi vt cht no c th gy hi ln n c th sng v h sinh

thi, lm bin i sinh l, sinh ha, ph v cn bng sinh hc, gy ri lon chc nngsng bnh thng, dn n trng thi bnh l hoc gy cht.

- Nng hoc liu lng ca mt tc nhn ha hc hoc vt l s quyt nh n

c phi l c cht hay khng. V vy, tt c cc cht c th l cht c tim tng. Theo

J.H.Dufus mt cht c l cht khi vo hoc to thnh trong c th s gy hi hoc git

cht c th . Tt c mi cht u c th l cht c, ph thuc vo liu lng s quyt

nh mt cht khng phi l cht c.1.3.2. Tnh c

1. nh nghia

- L mc tc ng nguy hi ca tc nhn c ln c th sng, n ph thuc vo

nng ca cht c v qu trnh tip xc.

- Kim tra tnh c l tin hnh nhng xt nghim c tnh nhng tc ng bt

li ca cc tc nhn ln cc t chc c quan trong c th trong iu kin tiu chun.

2. Cc c trng ca tnh c

- Tnh c ca mt cht tc ng ln cc c quan khc nhau hoc c th khc nhau

th khc nhau.

- Tnh c ca cc cht c khc nhau tc ng ln cng mt c quan hoc cng

mt c th th khc nhau

- Tnh c lun tn ti mt ngng gy c ring i vi mi tc ng ln c th

ca mi cht.

- Ngng gy c (TLV Threholol Limit Value): c a ra khi quan st trong

trong thi gian nht nh pht hin ra tc ng ca c cht i vi c th sng.

- Tnh c c th c tnh thun nghch v khng thun nghch. Tnh thun nghch

th hin l c cht vo c th sng c hp th, o thi m khng li di chng g

HbO2 + CO HbCO + O2



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Tnh khng thun nghch th hin l mt c cht khi vo c th s li di chng

nh dioxxin, furan...

- Tnh c c th biu hin qua nhim c cp tnh

Nhim c cp tnh: l tc ng ca cht c ln c th sng xut hin sm sau khitip xc vi c cht trong mt thi gian ngn hoc rt ngn.

- Tnh c c th biu hin qua nhim c mn tnh

Nhim c mn tnh: l tc ng ca c cht ln c th sng xut hin sau mt

thi gian di tip xc vi tc nhn c v c th hin suy gim sc khe, xut hin bnh

tt.

- Tnh c ca c cht i vi c th c th thay i, tng ln hoc gim i khi tn

ti nhiu c cht trong cng mt c th.

3. Cc tc nhn ca tnh c chn lc

- Tnh c ph thuc vo kch c ca vi sinh vt. Lng cht c cn cho sinh

vt c kch thc b t hn so vi sinh vt c kch thc ln

- Tnh c ph thuc vo t l gia cn nng v din tch tip xc b mt. Con vt

cng nh th din tch b mt ca n trn 1g cn nng cng ln.

Din tch tip xc c tnh S(m2)=10

3/2W

V d: T l cn nng ca con ngi (70kg) so vi con chut (200g) l 350 ln

nhng t l din tch b mt tip xc ca con ngi v chut ch l 55.

- Tnh c ph thuc vo tc hp th cht c qua da.

V d: DDT c nh nhau i vi c th ca c cn trng v ng vt nhng khi s

dng din tch rng th lng DDT dng tiu dit ng vt phi ln hn nhiu so vi

cn trng do da ca cn trng c cha cht kitin d cho cht c xm nhp v khng

c bao ph bi lp lng nh ng vt.

2. Cc yu t nh hng n tnh c

Mc gy c ca mt cht c c hi ln c th sinh vt ph thuc rt nhiu yu

t. Trong , c mi trng xung quanh ln trng thi ca c th b tc ng; cc c



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Chuyn : Ma axit GVHD: TS Mai TunAnhtrng ging, loi, gii tnh, s thch nghie, kh nng khng hoc mn cm ca cc

c thgp phn vo mc ca tnh c i vi c th sng.

Di y, mt s yu t c nh hng n tnh c

2.1. Bn cht ca tc nhn gy c (bn cht ha hc v bn cht l hc ca chtc)

Bn cht ha chtv cc c tnh l ha ca chng s xc nh mc cc hot

tnh sinh hc. Cc kh rt d dng b hp th thng qua h thng h hp, c bit l thng

qua phi i vo mu v cc phn ng ca c th i vi cc cht kh ny thng l

phn ng cc b (nh i vi zn) hay h thng (nh t vi cc cht kh dng gy

m). Hi nc v cc ht bi lng cng c th d dng c hp th t h thng khqun. Chng c th kt hp vi nc trong h thng kh qun v to ra nhng nguyn vt

liu cho phn ng v gy nn nhng tn thng cc b, nh hi formaldehyde, lu

hunh i-xyt, xyt nit. Cc ht bi c th di chuyn n ph nang v hn ch s trao

i kh y. Nhng ht ny bao gm c cacbon v silicat. Cc ha cht v ngay c cc

vi sinh vt cng c th c hp th vo cc ht bi ri i vo c th v gy ra nhng

phn ng mang tnh cc b hay mang tnh h thng. Cc protein b chuyn ha trong h

thng tiu ha v thng thng chng mt ht hot tnh.

C nhiu yu t quyt nh tc hi ca cc c cht i vi c th:

a) Cu trc ha hc

Theo Lazarev, cu trc ha hc quyt nh tnh cht l ha v hot tnh ha hc ca

c cht. Nhng tnh cht trn li quyt nh hot tnh sinh vt hc ca c cht.

Visacscon a ra quy lut hot ng cc cht ha hc da vo cu trc ha hc:

+ Cc hp cht cacbonhydro c tnh c tng t l thun vi s nguyn t carbon c

trong phn t, th d:

Pental (5C) c hn butan (4C)

Butylic (4C) c hn etylic (2C)

+ Trong nhng hp cht c cng s nguyn t, nhng hp cht cha t nguyn t

c hn cc hp cht cha nhiu nguyn t, th d:

Nitrit (NO2) c hn nitrat (NO3)



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Oxyt Carbon (CO) c hn carbonic (CO2)

+ Khi nguyn t halogen thay th cho hyro nhiu bao nhiu trong cc hp cht hu

c th c tnh tng ln by nhiu, th d:

Tetracloruacarbon (CCl4) c hn Chlorofoc (CHCl3)

+ Gc no (-NO2) v gc amino (-NH2) thay th cho H trong cc hp cht carbua

vng nhiu bao nhiu th c tnh tng ln by nhiu, th d:

Nitrobenzen (C6H5NO2) c hn benzen (C6H6)

b) Tnh cht l hc

Tnh cht l hc ca c cht c c trng bng nhit si bay hi, ho

tan, kh nng hp ph...

Nhit si xc nh cc hng s l hc khc nh tnh bay hi v tc bay hi.

Cc cht bay hi cao to ra nng cao trong khng kh.

Cc cht c tnh bay hi c kh nng to ra trong khng kh ca ni lm vic mt

nng cao. Mt khc cc cht c tnh bay hi cao s lm tng t trng khng kh ln.

Tnh ha tan: Cc tnh cht l ha k c dng ca ha cht (cht bt, cht lng,

cht kh) v ha tan trong m s xc nh tc v cng vn chuyn ha cht qua

mng t bo cng nh nng ha cht ti c quan tip nhn. c cht cng d ha tan

trong nc, trong dch th v m th cng c. Cc cht cng d tan trong mth c tnh

cho h thn kinh cng cao. Cc ha cht tan c trong m c th d dng i qua mng t

bo hn cc ha cht tan c trong nc. ha tan trong m c biu th bng h s

Oerton Mayer l t s gia ha tan ca mt cht trong m so vi nc.

V d: Benzen c h s l 300 c hn ru etylic c h s 2,5.

Mc ln ha cng lm nh hng n di chuyn ca ha cht. S lng ng sinh

hc cng ph thuc vo nhng tnh cht ny. S lng ng sinh hc y bao gm c

hp th, phn b, chuyn ha sinh hc, o thi v c cu tnh ng hc ca nhng qu

trnh ny. Trong qu trnh chuyn ha sinh hc, c th thng chuyn ha cc hp cht

tan trong m sang mt dng khc d o thi v t hot tnh hn di dng ha cht tan

c trong nc.



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Kh nng hp ph l kh nng tp trung nhng cht dng kh, bi, hi trn b

mt mt cht rn. Mc hp ph ty thuc vo kh nng hp ph ca vt liu xy dng,

nhit khng kh, nng c cht v thi gian tip xc.

c) Tc dng phi hp ca c chtTrong thc t khi c nhiu c cht cng tn ti th tnh c s thay i, c th tng

cng v cng c th tiu gim c.

2.2. iu kin tip xc

- Ngoi bn cht ca ha cht v cc c tnh l ha ca chng, phn ng i vi

mt ha cht thng b nh hng bi iu kin tip xc bao gm liu lng hay nng

, dng tip xc v thi gian tip xc. Liu lng c th tip nhn c v phng dinsinh hc ca tc nhn, nng ti c quan tip nhn s xc nh cng phn ng. C

th ni "liu lng lm cc cht tr thnh c cht".

Liu ln c th gy c tnh cp tnh, liu lng nh hn c khi c th gy nhim

c mn tnh hoc c th khng gy c. V d: Liu dng ca nitrat c hi ca vin

thc n l 200 mg /Kg bw cho gia sc. Trong khi l 1000-2000 mg /Kg nu phn b

c kh.

ng tip xc cng l mt yu t ng k nh hng n phn ng.

V d: ng vt tip xc vi methylene chloride qua ng h hp s b ung th,

nhng cc ng vt cng tip xc vi ha cht ny qua con ng tiu ha th khng b

ung th.

- Tip xc trong mt thi gian ngn thng ch b nhng tc ng gy hi mang tnhc th phc hi c, nhng nu tip xc trong mt thi gian di s b nhng tc hi

khng th phc hi c.

V d tip xc vi ru trong mt thi gian ngn c th lm cho gan khng th lc

ni m trong mt thi gian nht nh, nhng nu tip xc trong mt thi gian di th s

dn n bnh x gan.

-Phn ng i vi mt ha chtc th c xc nh bi ln ca mi lin ktvi c quan tip nhn, l s lng cc c quan tip nhn ring bit c ha cht



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Chuyn : Ma axit GVHD: TS Mai TunAnhchim gi v thi gian tng tc gia ha cht - c quan tip nhn. l hm s ca bn

cht mi lin kt ha hc (hydrogen hay Van deet Waals) v nng ha cht ti c

quan tip nhn. Liu lng hay nng cng ln th s c quan tip nhn tham gia cng

nhiu, s lin kt lu hn, phn ng gy ra ln hn v trong mt thi gian di hn.

V d, ngi ta tnh ton liu lng caffein trong 100 tch c ph c th gy cht

ngi; lng solanine tm thy trong 180 kg khoai ty c th gy cht ngi. Liu lng

ha cht c biu th nh mg/kg trng lng c th hoc mg/m2 din tch b mt c th.

-ng tip xc nh hng n phn ng ca ha cht do chng s xc nh mt

lng ln nh th no c thm nhp vo c th. Con ng tip xc thng thng l

qua ming vo n h tiu ha, qua da, qua h h hp.

V d, khi ta tip xc vi nc qua ming hay qua da, iu ny chng gy nn mt

tc ng xu no, nhng nu ta tip xc vi nc qua phi th iu ny c th lm cht

ngi.

- Cc vt cht c th c hp th qua ming. Mt s ha cht b phn hy do cc

axt c sn trong d dy, trong khi cc ha cht khc li c th d dng b hp th

trong d dy (v d nh ru). S c mt ca thc phm (loi v khi lng thc phm)

trong h tiu ha, tn ti ca cc bnh v trng thi cc vi sinh vt cng gy nh hng

n hp th.

- Cc vt cht, nht l cc cht tan trong m khi tip xc vi mt lp da nguyn

lnh c th gy nn nhng phn ng c tnh cht h thng hoc ch gy ra nhng tc ng

cc b.

Nhng nu nh da b xy xc th cc cht rt d thm qua da, vo c th v lc ny

barie ngn cn khuch tn ca vt cht qua da b lm cho km hiu qu.

- Vic hp th qua h thng h hp ph thuc vo tnh cht l ha ca ha cht, k

c kch c ht (chiu di v ng knh), tnh ho tan trong nc v ph thuc vo tc

v su khi th.

V d, nhng ngi v ngh nghip phi tip xc vi g v cc dung mi hu c,

nikel, cc loi du bi trn, crom c th s b mc bnh l lot hay thm ch ung th mi,

v mi phi lc cc cht ny hng ngy. Cc ht khng ha tan c th c th gy hi

n h thng h hp. V d cc si aming, cc bi than silic c th gy ln bnh vim x



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Chuyn : Ma axit GVHD: TS Mai TunAnhphi v thm ch aming cn gy nn ung th phi. Cc dng ht cht trn c th b cc

ha cht hay cc vi sinh vt bm vo b mt.

Cc ht vi ng knh t hn vi micron khng hp th m c y ra theo hi

th, cc ht vi ng knh nh hn 7 micron th tn ti trong kh qun v phi, cc htc ng knh ln hn 7 micron cc lng mi chn li hay y li ln mi theo mt c

ch c bit, qu trnh ny gi l qu trnh lm sch, sau c chuyn vo cung hng

v b nut vo thc qun.

Trong h tiu ha, cc ht ny c th tng tc vi thnh rut v c th trc tip gy

ra tn thng. Ha cht hay vi sinh vt bm trn ht cng c th tng tc vi thnh rut

v gy tn thng, hoc lm ri lon hot ng bnh thng ca cc vi sinh vt ng

rut, hu qu gy tn thng hay thay i chc nng ca chng.

Phn nhiu nhng tip xc vi ha cht gy ra ng thi do nhiu ng, nhng

khng phi tt c cc ha cht u c hp th qua tt c mi ng. V d cc thuc

tr su nhm ln hu c nhn chung hp th vo c th qua tt c cc ng v gy c

nh nhau khng phn bit v con ng thm nhp.

Ung vitamin D vi nng cao c th gy c, nhng nu tip xc vi vitamin D

qua da th khng gy nn c tnh no. Thy ngn kim loi khng c nu b thm nhp

qua tt c cc ng; nu thm nhp qua ng thc n n s c thi nguyn vn ra

ngoi. Song nu hi ca thy ngn b ht vo qua phi hay tip xc vi hi qua da th n

s b hp th v gy nn c tnh rt ln.

2.3. Loi, gii tnh, tui v cc yu t di truyn ti thi im tip xc

Loai:Phn ng i vi mt ha cht mang tnh c th ring v loi.

- Mt cht c th rt c i vi loi ny nhng khng h gy tc hi vi loi khc.

V d:

+ B-naphthamine gy u bng quang ca linh trng, chut chi, ch nhng li

khng gy tc hi i vi chut bch v chut ch.

+ Methanol rt c hi i vi con ngi v cc loi ng vt linh trng, n c th

gy m cho nhng loi ny, nhng khng gy m cho cc loi khc.



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+ Cht triorthocresyl phosphate (TOCP) gy bnh demyelination cho ngi v cho

g nhng khng gy cc bnh ny cho cc loi khc.

+ Nitrobenzen gy nn bnh v mu gi l methemoglobineme v n rt c i vi

con ngi nhng li khng c i vi kh, chut hay th.+ Alflatoxin c th gy nn ung th cho c hi. 1,2- dichloroethane gy ung th

phi chut nht nhng khng gy ung th cho chut to.

- C quan ni tng m c cht tc ng vo cng khc nhau i vi nhng loi

khc nhau. V d, dibutylnitrosamine gy ung th gan chut ln v cho ln nhng li gy

ung th bng quang v ung th thc qun chut nht. C s ca tnh c th i vi cc

loi ph thuc nhiu v s chuyn ha sinh hc, khc nhau v sinh l (v d: Cc loigm nhm khng bao gi nn, nhng ch v mo th li nn rt d dng hay qu trnh

trao i cht, h hp ca cc loi gm nhm cao hn so vi ngi), khc nhau v h tiu

ha gia cc sinh vt khc nhau v hnh th (da ca ch khc vi da ngi nn ch khng

b tot m hi), khc nhau v kch thc, khi lng hay din tch b mt c th.

Tc ng ca cc ha cht trong c th ngi ch c nh gi khi c cc s

liu c cht hc thu c t cc th nghim da trn c s ng vt. Ni chung, cc loi

ng vt phn loi gn ngi c th c coi l loi ph hp hn nghin cu c cht

hc. Trong mt s trng hp nghin cu c th s dng n cc loi ng vt mang tnh

nhy cm cao.

Gii tnh :Phn ng vi ha cht cn ph thuc nhiu n gii tnh.

- V d, chut c nhy cm hn chut ci gp 10 ln khi b tip xc lu d i vi

DDT. Chut c nhy cm nht vi tn thng h tit niu do hyrocacbon bay hi, sau

sinh u thn.

- Tnh nhy cm i vi cht c ca mt s loi ph thuc vo gii tnh nh sau:

(Theo NC State University)

Loi c cht Tinh nhy cm

Loi gm nhm (Rat)EPN, Warfarin,

Strychnine

Ci (F) > c (M)

Loi gm nhm (Rat)Aldrin, Lead,

Epinephrine

M > F



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Mo Dinitrophenol F > M

Tho Benzene F > M

Chut (Mouse) Folic axit F > M

Cho Digitoxin M > FBng 1- Tnh nhy cm ca mt s loi i vi c cht ty thuc vo gii tnh

th biu din tc ng ca CYP i vi loi gm nhm c v ci:

Hnh 1- th biu din tc ng ca CYP i vi loi gm nhm c v ci

- S hot ha khc nhau ca 2 AAF i vi chut c v chut ci:

Hnh 2- S hot ha khc nhau ca 2- AAF i vi chut c v chut ci

- Mt s cc hp cht photpho hu c c hn i vi chut nht ci v chut ci to

trong khi mt s hp cht khc li c hn i vi chut c. Do nhng s khc nhau v

gii tnh thng b mt i khi b phn sinh dc b ct b v nhng khc nhau ny cng

ch c th hin nhng c th trng thnh, c ch hot ng y l c ch hot

ng do hormon iu khin.



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tui:Phn ng i vi ha cht c th b nh hng bi tui ca c th ti

thi im tip xc.

Nhn chung, c nhng sinh vt hay c th ang pht trin v hay gi d b cc tc

dng c hi ca cht c hn l ngi trng thnh. iu ny lm tng tnh nhy cm,c th l cc c th cn rt tr cha pht trin y cc mc y cc enzyme kh

c v cc mc ca cc enzym ny gim s lo ha c th. Mt h thng min

dch pht trin khng y tr em v kh nng min dch cc c th gi b suy gim

cng ng gp mt vai tr vo .

V d, DDT khng c tnh c hi tc thi i vi nhng con chut mi sinh nhng

chng s tr nn c hi hn rt nhiu i vi nhng con chut c tui i lu hn;

Parathion li c hi hn i vi nhng con chut mi sinh hn l nhng con chut c

tui i lu hn; boric axt c vi chut mi sinh hn l vi chut c tui i lu hn...

C s ca nhng khc bit trong phn ng c th lin quan n kch thc c th,

trng lng, b mt, thnh phn cu to c th, kh nng chuyn ha sinh hc, hay cc

yu t khc cha c xc nh.

Yu t di truyn:

Yu t di truyn cng c th quyt nh s phn ng ca c th i vi mt s cht

c.

Ph thuc vo c im ca tng loi: c tnh ca mt cht thng khc nhau i

vi mi loi. Nguyn nhn l do kh nng chuyn ha sinh hc, hp th, phn b, o

thi ca c cht i vi tng loi khc nhau l khc nhau. V d nh thuc dit cn

trng thng c i vi cc loi cn trng hn so vi ngi v loi ng vt c v.

2-naptylamin thng to khi u bng i ch v ngi nhng khng to ra khi u

c th chut.

c im ca tng c th sng trong loi: do c im sinh hc ca cc c th

khng ging nhau nn kh nng b nhim c cng khc nhau. Mt s ngi rt mn cm

vi mt s tc nhn nh nh sng, bi, mt s loi thc phm so vi nhng ngi khc.

Qua nhiu nghin cu cng cho thy rng nguy c b ung th cng ph thuc vo

yu t di truyn.



16/30


C mt s bng chng r rng cho thy rng ung th l mt bnh do s bin i

ca gene gy ra. Cc t bo khi u c s lng nhim sc th bin i v cc nhim

sc th thng c s sp xp li. Mt vi chuyn on l c trng vi cc dng ung th

nht nh. Phn ln cc tc nhn t bin l cc tc nhn gy ung th. T bm

(predisposition) vi cc dng ung th c tm thy l di truyn mt s gia nh. C

ba loi gene lin quan n ung th c pht hin l gene ung th (oncogene), gene c

ch khi u (tumor suppressor gene) v gene sa cha DNA (DNA repair gene).

Phn ln gene ung th c ngun gc t protooncogene. Protooncogene l cc

gene m ho cc sn phm kim sot s sinh trng v bit ho ca t bo.

Protooncogene c hot ho to thnh gene ung th do t bin hoc biu hin qu

mc. Ln u tin chng c pht hin trong cc retrovirus gy ung th, nhng cng c

th c pht hin trong cc khi u khng c virus bng s chuyn nhim vo trong cc

t bo 3T3 ca chut. Gene ung th cc retrovirus l v-onc v khi trong cc khi u l

c-onc. Thnh thong gene ung th c khuych i trong cc t bo khi u. Phn ln cc

gene ung th hot ng nh allele tri lm tng chc nng t bin dn n loi b kh

nng iu ho ca s kim sot chu trnh t bo. Ngc li vi gene c ch khi u, gene

ung th khng biu hin cc t bin dng mm (germline mutations) m cc t bin

ny gy nn cc hi chng ung th di truyn (inherited cancer syndromes). Trong khi

t bin soma gy ra ung th n pht (sporadic cancer).

Mt s khi u do chuyn on c hiu lm tng s phin m ca gene ung th

c m t c im. Hin tng ny c tm thy u lympho ca Burkitt (Burkitt's

lymphoma).Hoc s dung hp ca hai protooncogene c th to thnh mt gene mi l

vi cc c tnh ung th c quan st bnh bch cu dng tu mn tnh (chronic

myeloid leukemia).

Gene c ch khi u cn n c hai bn sao tr nn bt hot trc khi cc khi u c

th pht trin. Cc t bin ny l t bin ln. Thng thng s bt hot xy ra l do

t bin im mt allele v mt mt allele khc. S bt hot ca gene c ch khi u xy

ra cc t bo soma trong qu trnh pht trin ca khi u. Gene c ch khi u c

nghin cu k nht l gene p53. Trong hn 40% cc khi u ca ngi, gene ny b t

bin. p53 ng vai tr iu ho chu trnh t bo v qu trnh cht theo chng trnh ca tbo (apoptosis)



17/30


Mt s ung th him gp v mt phn nh ung th ph bin tp hp li trong

mt s gia nh. Cc gia nh ny c gi l c t bm di truyn (hereditary

predisposition) vi ung th. T bm di truyn ny c th tr thnh mt dng c trng

ca ung th v d nh ung th v hoc mt loi ung th khc.

T bm di truyn c th tng ln thng qua cc t bin dng mm ca gene c

ch khi u. Tt c cc t bo soma ca mt c th mang mt allele t bin v c nguy c

hnh thnh khi u tng cao do s bt hot ca mt allele n bnh thng. V d ngi

gm c gene vng mc (retinoblastoma -Rb) nm trn nhim sc th 13 v gene t bm

di truyn ung th v v ung th bung trng (BRCA1) nm trn nhim sc th 17. Allele

bnh thng b bt hot trong khi u. Cc gene ung th gia nh thng b t bin soma

trong cc trng hp khng thng xuyn (khng di truyn) ca cng loi ung th.

Ung th di truyn cho thy kiu di truyn do gene tri trn nhim sc th thng

bi v ngi bnh truyn t bm di truyn cho mt na s con ci ca h. Tuy nhin cc

t bin gene c ch khi u l t bin ln. N c gii thch bng thc t l nu mt

c th ch c mt bn sao hot ng chc nng ca gene c ch khi u trong mi t bo

th n rt thch hp cho vic mt t bin th hai s gy bt hot bn sao hot ng chc

nng bnh thng ny trong mi t bo. Sau cc t bo t bin kp ny c th phttrin thnh mt khi u.

Cc gene sa cha DNA cng kt hp vi ung th di truyn. V d bnh da sng

ho sc t (xeroderma pigmentosum) do mt t bin ln trn nhim sc th thng.

Ngi bnh rt nhy cm vi nh sng mt tri bi v h thiu endonuclease xc tc cho

vic sa cha DNA. Cc allele t bin ca mt s gene khc c th dn hnh ca gene

tng cng t bin (mutator phenotype).

2.4. Tnh trng ca sinh vt ti thi im tip xc

Tnh trng sc kho ca sinh vt, trong tnh trng bnh tt c th gy nh hng

trc tip n cc phn ng ca ha cht. Thng thng iu ny gy nn nhng nh

hng xu n tn ng ca ha cht trong c th sinh vt. Thc n c y protein v

cc cht vi lng (v d nh vitamin) c th bo v c th khi c tnh ca mt s tc

nhn. Cc loi chut nht v chut to khi c n thc n dinh dng nhng t v khi

lng, cho thy c nhng khi u pht trin trong c th chng.



18/30


Thiu vitamin c th ko di thi gian hot ng ca ha cht (v d, bnh thiu

vitamin C ko di thi gian hot ng ca pentobarbital).

Khi gan b bnh (v d nh khi b tip xc vi cc hydrocarbon b halogen ha) th

phn ng ca gan i vi ru c th b ko di hn do c ch chuyn ha sinh hc caru trong gan b thay i. S tn ti cc bnh v gan hay phi lm tng cc tc ng c

hi ca cc tc nhn gy c i vi gan v phi. S tn ti ca cc bnh v thn gy nh

hng n s o thi cc ha cht v ko di thi gian hot ng ca cc ha cht ny

trong c th.

2.5. S c mt ca cc ha cht trong c th sinh vt, trong mi trng v trong

thi gian tip xc

Cng vic nh gi c tnh ca hn hp cc loi ha cht s dng trong cuc sng

l vic kh khn i vi cc nh nghin cu c cht hc. Nhn chung, mt s mi tng

tc gia cc ha cht, nh gia cc dc phm vi nhau, gia dc phm vi thc phm

(vic hn ch s dng cc sn phm t sa khi ang s dng khng sinh tetracycline do

s lin kt ca canxi vi tetracycline v to thnh nhng hp cht khng tan) cng

c khng nh. Nhng nghin cu cn thc hin thit lp ni quy, hng dn s

dng ha cht mt cch an ton v ang c thc hin.

Cc v d v mi tng tc trong c cht hc nh: tng c tnh ca carbon

tetrachlride do phenobarbital, tng cc phn ng ca phi i vi cc tc nhn gy ung

th do vic ht thuc, ht cc kh tim nng gy ung th.

Tng tc c th c phn ra: dng tng tc ho hc v tng tc sinh hc.

Tng tc sinh hc gy nh hng n mt ha cht trong qu trnh tn ng sinh hc,

hoc hot tnh c quan tip nhn mt ha cht khc. Tng tc ha hc lin quan n ccphn ng gia cc ha cht, gy nn hu qu trong vic hnh thnh cc cht c hot tnh

v khng c hot tnh v phng din sinh hc. Mt khc tng tc ha hc c th xy ra

bn ngoi hoc bn trong c th.

Cc yu t nh hng n tng tc bao gm: a im tng tc, mi lin quan

gia liu lng - p ng ca cc cht tham gia tng tc, mi lin h vi thi gian,

nhng c tnh v phng din l ha hc v tnh trng ca i tng tip xc.



19/30


Tng tc ha hc c th xy ra bn ngoi c th (exvivo), trong khng kh (v d:

s to thnh axt sulphuric t kh xt lu hunh v nc), trong nc (nh to thnh

trihalomethane t axt humic v chlorin), v trong thc phm (nh hp th cc cht vi

lng). Tng tc sinh hc c th xut hin bn trong c th (exvivo) v thng lin

quan n s lng ng sinh hc (bao gm hp th, phn b, chuyn ha sinh hc, o

thi v.v...), hoc hot tnh ca c quan tip nhn.

Tng tc xy ra trong c th c th lin quan n hp th cc cht tham gia tng

tc v c th b nh hng bi cc tc nhn l ha (nh pH, pKa, tnh tan, c ht, kch

thc phn t, s lin kt), hp ph, cnh tranh c cc a im di chuyn qua mng t

bo, ng nht ca b mt hp th. Vn chuyn ca cc cht tng tc thng lin quan

n cc yu t l ha, cc protein lin kt (nh albumin), cc phn t c kch thc ln

v s lu chuyn ca mu. Phn b v tch tr ca cc cht tham gia tng tc lin quan

n cc yu t. l, ha, cc protein lin kt, cc phn t c kch thc ln v s lu

chuyn ca mu.

Chuyn ha sinh hc ca cc cht tng tc lin quan n ng nht ca cc m

tham gia chuyn ha, cc enzym kch thch, hoc cc enzym c ch v s lu chuyn ca

mu. S o thi cc cht tng tc lin quan n cc yu t. l ha, ng nht ca cquan tham gia o thi, cnh tranh c c a im lu chuyn mu. Mc hot

ng ca c quan tip nhn cc cht tng tc lin quan n cc yu t l ha mi lin

kt (tnh c th/ tnh chn lc/ i lc). S tng tc vi cc c quan tip nhn tch cc

c th to thnh phn ng. S tng tc vi cc c quan tip nhn khng tch cc khng

gy nn phn ng m i khi cc cht tng tc li tch tr li trong c th.

Trao i cht, cng gi l s chuyn i sinh hc , l mt nhn t chnh trong vic

xc nh c tnh. Cc sn phm ca s trao i cht c gi l cht chuyn ha. C hai

loi hnh trao i cht kh c v hot ha. Kh c l mt qu trnh m theo mt

mt cht c khi xm nhp vo c th c chuyn i sang mt dng t c hn. y l

mt c ch phng v t nhin ca sinh vt. Qu trnh hot ha l qu trnh m theo

mt mt cht c khi xm nhp vo c th c th c chuyn i sang hnh thc hot

ha hn hoc c hi.

Tc bi tit l mt yu t chnh nh hng n c tnh ca mt cht c. Thnl c quan bi tit chnh, tip theo l ng tiu ha, v phi (i vi cc loi kh). Cht



20/30

Chuyn : Ma axit GVHD: TS Mai TunAnhc cng c th c bi tit qua m hi, nc mt, v sa. Mt khi lng ln mu

c lc qua thn. c cht ha tan c hp th li v tp trung trong cc t bo thn

lm tng tim nng c hi ca n.

Sau khi cht c c phn phi n cc c quan trong c th th s xy ra qutrnh chuyn ho cht c. Chuyn ho cht c trong c th thc cht l qu trnh sinh

ho chuyn cc cht c thnh cc cht hot ng hay bt hot. Qu trnh ny thng

xy ra gan, thn hay cc c quan khc ca c th, nhng mc gii hn khc nhau.

c tnh chung nht ca qu trnh ny l cc sn phm ca n thng phn cc hn so

vi cc cht ban u, do s thun li cho qu trnh tip theo l o thi cht c vo

nc tiu hay mt.

Mt chuyn ho sinh hc c th dn n nhng thay i v c tnh c nh sau:

- Chuyn ho mt hp cht hot ng thnh khng hot ng

- Chuyn mt cht khng hot ng sang dng hot ng

- Chuyn mt cht khng hot ng sang mt dng khng hot ng khc

- Chuyn mt cht hot ng sang dng hot ng khc.

S chuyn ho:


Cht c

Khng i Chuyn hoKh c

Gc hot tnhKhng c

Gy tc ng lnc th

Bi tit

Tin cchuyn thnh dng c


21/30


Hnh 3- S chuyn ha ca cht c

Qu trnh chuyn ho (trao i) theo 2 giai on: Giai on I gm cc phn ng lm

cho cht c hot ng hn chuyn thnh cc dn xut vi cc nhm chc thch hp cho

cc phn ng giai on 2. Giai on 2 phn ng gn cc nhm phn cc cao ln ccht, nhm h tr qu trnh bi tit bng thn v gan.

Pha 1 trao i cht: gm cc phn ng oxy ho, kh v thu phn.

Pha 2 lin hp

Phn ng pha 2 l s kt hp mt cht ni sinh tan trong nc vo tc cht xm

nhp (cht ngoi sinh). Cc phn ng pha mt p dng i vi cc hp cht tan trong m

v c xem nh l gn mt "cnh tay" vo phn t pha 2 c th nm vo. "Cnh tay"ny thng l cc nhm hydroxyl, ni m cc enzim lin hp s gn mt phn t ng

hay acid vo thnh mt sn phm cui tan trong nc v c th c bi tit bng

gan, thn.

Kt qu ca cc phn ng lin hp l to thnh cc dng enzym ca gluctronide

ethereal sulfate, mercapturic acid thng qua s lin hp vi glutthione, amino acid ecety

amin v cc hp cht methyl.

Mc phn ng i vi ha cht trong h thng sinh hc l hm s lng ha cht

c hot tnh sinh hc ti c quan tip nhn, ti m t bo c tip nhn, thi gian tng

tc gia ha cht v c quan tip nhn; phn ng i vi mt ha cht l hm s ca liu

lng v iu kin tip xc, k c thi gian tip xc. Mc ca mi tng tc c cht

hc ph thuc vo liu lng.

Mc ca mi tng tc trong c cht hc ph thuc vo mi lin quan vi thi

gian tip xc; c hi ca cc mi tng tc tng ln nhiu khi mt tip xc b tng.

Nu nh cc tip xc xy ra ng thi, tc ng ln lng ng sinh hc l rt quan

trng

Cc yu t l ha gy nh hng n qu trnh ton ha, kch thc hay ha tan

s gy nh hng.n vn chuyn qua mng t bo, phn ng i vi ha cht.

Tnh trng sc kho v dinh dng ca i tng tip xc s nh hng n phn

ng i vi ha cht.



22/30


23/30


Suy gim c th lin quan n tnh chc nng, sinh l, ha hc, lng ng sinh hc,

sinh ha hc.

Suy gim chc nng hoc suy gim sinh l xut hin khi hai hay nhiu ha cht

to ra mt tc ng ngc li trn cng mt c quan v lm trung ha cc tc ng (vd, thuc gim au c dng khng ch nhng cn co git), hoc trn cc c quan

khc nhau to ra nhng tc ng tng tc v sinh l (v d, histamin gy nn hin tng

gim p sut mu v norepinephrine gy tng p sut mu); cc ha cht thng c mt

ng thi.

Suy gim tnh cht ha hc xut hin khi hai hay nhiu ha cht tng tc v phn

ng to thnh mt hp cht km hot tnh hn; v d: cht to thnh Ca vi tetracycline.

suy gim lng ng sinh hc v tnh cht sinh ha xy ra khi mt ha cht thay i lng

ng sinh hc ca ha cht khc v do vy lm gim nng cht ti c quan tip xc

v suy gim hiu qu hay c tnh ca ha cht (v d, cc enzym kch thch lm thay i

c cu chuyn ha sinh hc lm thay i c tnh hay hiu qu ca ha cht).

Gim cc c quan tip nhn xut hin khi hai hay nhiu ha cht cng cnh tranh

cho mt c quan tip nhn, kt qu l tc ng cui cng b suy gim hay ch cn to r

mt khonh (lc). S suy gim cc c quan tip nhn thng c dng cp nnh cc mc (v d, O2 v CO. Cng cnh tranh trn cng mt c quan tip nhn Hb),

cc ha cht thng c mt ng thi

Phng php xt duyt n gin xc nh nhng tng tc c th c bao gm

vic xc nh ng cong liu lng - phn ng v xc nh LD20 cho mi ha cht. Sau

kt hp s liu li vi nhau v nh gi kh nng gy t vong. Nu kh nng gy t

vong vt qu 40%, c th gi thit l s tng trng vt bc; nu nh kh nng gyt vong t hn 40% th gi thit l suy gim; nu kh nng gy t vong bng 40% c

th gi thit tng tc l cng them.

2.6. Chp nhn hay thch ng

Chp nhn hay thch ng l gim bt tnh phn hi (p ng) i vi mt ha cht

khi c th tip tc phi tip xc vi ha cht. C s ca vic thch ng thng l kch

thch enzym tham gia n qu trnh chuyn ha sinh hc. V d: Mt s ngi thch ng

vi cht nicotine, caffeine v ru.



24/30


Trong mt s trng hp, trao i cht mt s loi c th ging nhau nhng cc

enzim tin hnh cc phn ng trao i ny th c th khc nhau.

Trong hot ng xc tc, c nhng cht tc ng lm tng cng hot ca

enzym, gi l cht hot ho. Nhng li c nhng cht lm gim hoc t lit hot ng caenzym, gi l cht c ch.

Nguyn nhn ca hin tng ny c dnh lu ti trung tm hot ng ca enzym v

cu trc phn t (nht l cu trc bc 3) ca protein - enzym.

- Cc cht hot ho enzym nh mt s ion kim loi Cu 2+, Zn2-, Ca2+, Mn2+, Mg2+,

Co2+...

- Cht c tc ng c ch enzym thng l cht c i vi c th.

a. Gii thch c ch hot ho enzym

Trong c th enzym c sn sinh cc c quan hay cc tuyn. Nhng enzym ny

ban u thng dng cha hot ng gi l chun enzym (proferenzyme) mun hot

ng c enzym phi nh cht hot ho.

C 3 kiu hot ho:

* Cc kim loi ho tr 2 tham gia vo cu to trung tm hot ng vn chuyn

in t hoc lm cu ni gn c ch vo enzym

Hnh 4- Mt kiu hot ha enzim

* Ct mt on enzym o trung tm hot ng ca enzym

N mt i mt on peptid pha N cui c th l do tc dng ca acid



25/30


* Cu to ti trung tm hot ng ca enzym

Enzym trypsinogen c enterokinase t trng tc ng lm mt mt on peptid

(lin kt hydro b t) mch cn li s co rt cu to v cu trc bc 2, 3 c trung tm

hot ng mi l se rin v histidin

Hnh 5- Bin i ti trung tm hot ng ca enzim

b. Gii thch c ch c ch ca enzym

Qu trnh c ch ca enzym l qu trnh trung tm hot ng b phong b. Hin

tng c ch ca enzym l hin tng rt ph bin trong i sng sinh vt, 90% ng c

l do enzym b c ch.

Nhng cht thng gy ra hin tng c ch enzym l kim loi nng, hp cht hu

c v v c

V d: Ng c HCN do n sn v anion CN lin kt cht ch vi Fe3+ ca h thng

Cytocrom - cytocrom oxydase.

Fe3+ b lin kt vi CN thnh Fe2+CN nn in t khng truyn i c v s h

hp ca m bo b gin on.

Gii c: Tim vo c th cht oxy-ho mnh nh xanh metylen hoc Na2S2O3.

Xanh metylen bin Hb thnh mt- hemoglobin (Hb.OH).



26/30


Cytorom dng Fe2+OH khng bn nn d phn hu thnh Fe3+ v H2O. cn Hb.CN

lc a v gan v kh c di dng:

Nc ong c enzym ph hu NAD (m NAD l nhm ghp ca enzym oxy - ho

hon nguyn) nn gy cho ng vt b ong t hin tng ngt. Cm gic au l do cccht acid khng c oxy - ho tch li kch thch ngn thn kinh gy nn.

Mt s cht khc nh Stilbamidin hoc curare th hin tnh c ch bng cch bt trung

tm hot ng ca enzym axetylcholin esterase.

Hnh 6- Men acetycolin estera

Curare cng nh stilbamidin c 2 nhm mun cch nhau 13 - 1 sao tng ng

qung cch ca on mang in tch m trong trung tm hot ng ca enzym do cht

ny d bt kn.

c. C ch chuyn ha cht ngoi lai

Tnh c chn lc c th ph thuc vo c ch chuyn ha cht ngoi lai.

V d: thuc tr su melathion da trn s chuyn ha bi cytochrome P-450 tr

thnh malaoxon, y l cht c ch ca acetyl chlornesterase. Nhng khi a vo c th

bng ng tiu ha th i vi c th chut t chu tc ng bi cht c ny hn so vi



27/30

Chuyn : Ma axit GVHD: TS Mai TunAnhrui nh 38 ln. Vic ny c gii thch do ng vt c v cha nhiu enzim estaraza

hot tnh hn.

Pyrithamine Trimethopr

Hnh 7 - Cu trc ca pyrithamine v trimethoprim

Mt trng hp th v ca tnh c chn lc l vic s dng pyrethroids tng hp nh loi

thuc tr su. Nhm hp cht ny c tm thy t nhng c cht xut hin trong t nhin gi

l pyrethrins chit ra t hoa chrysanthemum.

Hnh 8- Cu trc ca pyrethrin

Hnh 9 - Chuyn ha ca malathion thnh malaoxon

Cht pyrethrins c tnh c chn lc cao i vi cn trng. V d, mt cht trong nhm

pyrethroids l cht permethrin, LD50 ca permethrin i vi chut gp 1500 ln so vi chu

chu sa mc. C l bi v c tnh ca nhm pyrethroids tng dn khi nhit gim nn chngdng nh c i vi loi mu lnh hn l loi mu nng. V vy, s ph thuc vo nhit c


P-450


28/30

Chuyn : Ma axit GVHD: TS Mai TunAnhth l nguyn nhn i vi c tnh chn lc i vi cn trng. Cht pyrethroids tht s c i

vi mt loi c trong mt quan st ti phng th nghim. Mt kh nng khc l pyrethroids tri

qua qu trnh km hm sinh hc nhanh chng, gi l qu trnh thy phn ca cc lin kt este,

xy ra ng vt c v nhng khng xy ra i vi cn trng.

2.7. Cc yu t mi trng v cc yu t khc c th nh hng n kh nng phn

ng ca c th i vi c cht

Cc yu t mi trng c th gy nh hng n p ng ca mt c th i vi

mt ha cht bao gm nhit , m, p sut, cc thnh phn cu thnh mi trng

xung quanh ti thi im tip xc, nh sng v cc loi tia phng x khc, tnh trng nh

, ting n, cc yu t x hi C ch cc yu t ny nh hng n phn ng bao gm

bin i qu trnh tn ng sinh hc, thay i sinh l hc v nhng tng tc c th c vha hc v vt l.

- Yu t pH v tnh axit: nh hng n kh nng ha tan, kt ta ca c cht.

Thay i pH s nh hng n c tnh ca nhiu hp cht ho tan. V d, amoniac

tr nn c hi nh lm tng pH. Khi pH thay i, th kt ta ca cc cation kim loi thay

i theo:

+ pH < 5 a s cc kim loi nng ha tan trong nc dng cation Zn2+, Pb2+, Cd2+,

Cr2O72-, cc kim loi dng cation sinh vt thy sinh d hp th;

+ pH > 8: a s cc kim loi nng dng kt ta nh Zn(OH) 2; Pb(OH)2; Cd(OH)2;

Cr(OH)3

+ Mi loi c c c s thch hp v mc pH trong mt phm vi hp ca n.

Trong phm vi ny, s gy ra vn sc khe cho n. V d: c chp Koi (Cyprinus

carpio) thch hp vi khong axit t 7 n 8,5; trong khi mt s loi c nhit i thch

nc c tnh axit.

+ Axit hay kim cao c th gy tn thng trc tip ln da, mang c, mt..

Nu tip xc vi mi trng c mc pH mc thp c th gy ra cng thng,

tng sn xut cht nhn v khuyn khch tng sn sinh ra cc biu m (dy ln ca biu

m da hoc mang) vi nhng hu qu i khi gy t vong.

Loi c cng phi duy tr pH khng i ca c th n, thm ch ngay c nhng bin

i nh v pH trong mu ca n cng c th gy t vong.



29/30


pH ca mi trng bn ngoi hoc mi trng nc c th tc ng v nh hng

n pH trong mu, dn n nhim axit hoc nhim kim ca mu.

- Nhit nh hng nht nh ln sinh vt:

+ Nhit thp tng cng s bin i sinh hc

+ Nhit cao lm tng tnh nhy cm i vi c cht v lm bin i s trao i

cht v iu chnh nhit ca c th.

+ Chng nhim c da tng khi thi tit nng.

+ Tnh c cng tng khi nhit cng gim, c ngha l c cht s c hn i

vi loi mu lnh hn loi mu nng.

- p sut kh quyn:

+ Thay i p sut l thng kt hp vi s thay i oxi phn ng li vi cc c

cht. V d: thay i sut ca oxy c s dng iu tr ng c do CO, thuc an thn

v xyanua.

- dn: dn lin quan n kh nng in gii ca 1 c cht, dn tng,

linh c ca cc c cht cng tng, dn n c cht d lan truyn n cc b phn ca

c th v gy phn ng ca c th.

- Yu t dinh dng v ch n ung:

+ S kh hot tnh ha hc ca cc hp cht trong ch n ung: Thc n c cha

canxi v km nh hng n kh nng hp th ca ch. Thc n c cht tannin v cc

protein c th phc hp vi cc c cht v lm gim s hp th ca chng.

+ Thiu hay tha cht dinh dng: Ch n ung thiu cht dinh dng, dn n

thiu nng lng, s gy ra hin tng gim ng trong mu v gim kh nng hot

ng chuyn ha ca cc enzyme chuyn ha. Thiu protein lm suy yu cc enzyme

tng hp MFO v lm c c glutathione gan.



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TI LIU THAM KHO

1. GS.TSKH L Huy B- c hc mi trng c bn- Nh xut bn i hc quc giathnh ph H Ch Minh

2. Sigmund F. Zakrzewski- Environmental Toxicology- Oxford University Press- 2002

3. Trnh Th Thanh c hc v sc khe con ngi Nh xut bn i hc quc gia H Ni 1999.

4.www.wepapers.com 10 Factor Affecting Toxicity.

5. Lecturer - Dr. Muhammad Adil Rasheed Assistant Professor.
http://www.wepapers.com/http://www.wepapers.com/http://www.wepapers.com/http://www.wepapers.com/

Documents

Tieu Luan Doc Hoc Moi Truong-16-10-Final