Bai 04 - Dai cuong va phan loai he than kinh thuc vat [bacsihoasung.wordpress.com].pdf

7/30/2019 Bai 04 - Dai cuong va phan loai he than kinh thuc vat [bacsihoasung.wordpress.com].pdf

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dc l hc 2007 - i hc Y H ni

(sch dng cho sinh vin h bc s a khoa)

Bi 4: i c-ng v phn loi

Mc tiu hc tp: Sau khi hc xong bi ny, sinh vin c kh nng:1. Phn bit c v gii phu, sinh l v dc l cc h giao cm, ph giao cm,adrenergic, cholinergic

2. Phn bit c cc tc dng sinh l ca h M - N- cholinergic

H thn kinh thc vt (cn gi l h thn kinh t ng) chuyn iu khin cc hot ng ngoi mun, c vai tr iu ha chc phn ca nhiu c quan, h thng cho gii hn sng ca c thgi c s n nh trong mi trng sng lun lun thay i.

H thng thn kinh thc vt hnh thnh t nhng trung tm trong no v tu sng, xut phtnhng si thn kinh ti cc tng, mch mu v c nhn. Trc khi ti c quan thu nhn, cc siny u dng mt xinap ti hch, v vy c si trc hch (hay tin hch) v si sau hch (hayhu hch). Khc vi nhng b phn do h thn kinh trung ng iu khin, cc c quan do hthn kinh thc vt chi phi vn c th hot ng t ng khi ct t nhng si thn kinh nchng.

H thng thn kinh thc vt c chia thnh 2 h giao cm v ph giao cm khc nhau v c giiphu v chc phn sinh l.

1. Phn loi theo gii phu1.1. im xut pht

- H giao cm xut pht t nhng t bo thn kinh sng bn ca tu sng t t sng ngc th

nht n t sng tht lng th 3 (T1- L3).

- H ph giao cm xut pht t no gia, hnh no v tu cng. no gia v hnh no, cc siph giao cm i cng vi cc dy thn kinh trung ng: dy III vo mt; dy VII vo cc tuynnc bt; dy IX vo c mi, cc tuyn tit nc mt, n c bt, tuyn tit nim mc mi, ming,

hu; dy X vo cc tng trong ngc v bng. tu cng, xut pht t cc t sng cng th 2n th 4 (S2- S4) chi phi cc c quan trong h chu.

1.2. Hch

- H giao cm c 3 nhm hch:

. Chui hch cnh ct sng nm hai bn ct sng

. Nhm hch trc ct sng, gm hch tng, hch mc treo v hch h v, u nm trong bng.

. Nhm hch tn cng gm nhng hch nm cnh trc trng v bng quang.

- H ph giao cm: cc hch nm ngay cnh hoc ngay trong thnh c qua n.

1.3. Si thn kinh

- H giao cm: mt si tin hch thng tip ni vi khong 20 si hu hch cho nn khi kchthch giao cm, nh hng thng lan rng.


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- H ph giao cm: mt si tin hch thng ch tip ni vi mt si hu hch, cho nn xung tcthn kinh thng khu tr hn so vi xung tc giao cm. Tuy nhin, i vi dy X th m riAuerbACh v m ri Meissner (c coi l hch) th mt si tin hch tip ni vi khong 8000si hu hch.

V hch nm ngay cnh c quan, cho nn cc si hu hch ph giao cm rt ngn.


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Hnh 4.1. Cu to gii phu ca h thn kinh thc vt

2. Chc phn sinh l2.1. Chc phn sinh l

Chc phn sinh l ca hai h giao cm v ph giao cm trn cc c quan ni chung l i khngnhau (bng 4.1)

Bng 4.1: p ng ca c quan vi h thn kinh thc vt

C quan Kch thch giao cm Kch thch ph giao cmLoi receptor p ng p ng

MtC nan hoaC co ng t

1 Co (gin ng t) ++Co (co ng t ) +++

Tim

Nt nh- thtTm nh1 (2)1(2)

Tng tn s ++Tng bin ++ Gim tn s ngng tim

Gim bin ++Mao ng mch

Mch vnhC vnDa, nim mcNoTngThn

1, 2, 2, 21, 211, , 21, 2, 1, 2

Co +; gin ++Co ++; gin ++Co +++Co nhCo +++; Gin +Co +++; gin +

Gin +Gin +GinGin--

Tnh mch 1, 2 Co ++; gin ++ -Ph qun

2

Gin + Co ++Rut

Nhu ngC thtBi tit

1, 2, 212

Gim +Co +c ch

Tng +++Gin +Tng +++

ThnTit renin 1, 1 Gim +; tng ++ -

T cung 1, 2 Cha: co (1); gin (2)Khng cha; gin (2)

Thay i theo chu kkinh...

C quan sinhdc nam

1 Phng tinh +++ Cng +++

Bng quangC bng quangC trn

21

Gin +Co ++

Co +++Gin ++

Gan 1, 2 Hu glycogen v tn toglucose +++

-


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TyAciniT bo

12

Gim tit +Gim tit +++tng tit ++

Tng tit ++--

T bo m 2, 1 (3) Hu lipid +++ -Ghi ch: - Cc receptor ca h ph giao cm u l cc loi receptor M

- Mc p ng t thp (+) n cao (+++)

2.2. Xinap v cht dn truyn thn kinh

Khi ta kch thch cc dy thn kinh (trung ng v thc vt) th u mt ca cc dy s titra nhng cht ha hc lm trung gian cho s dn truyn gia cc dy tin hch vi hu hch,hoc gia dy thn kinh vi cc c quan thu nhn. Cht ha hc lm trung gian cho s dn truyn gi l cht dn truyn thn kinh.

H thng thn kinh ca ngi c hng chc t nron. S thng tin gia cc nron cng davo cc cht dn truyn thn kinh. Cc thuc nh hng n chc phn thn kinh thng l thngqua cc cht dn truyn thn kinh .

Cht dn truyn thn kinh hch giao cm, ph giao cm v hu hch ph giao cm u lacetylcholin, cn hu hch giao cm l noradrenalin, adrenalin v dopamin (gi chung lcatecholamin). Cc cht dn truyn thn kinh tc ng n mng sau xinap lm thay i tnhthm ca mng vi ion Na+, K+ hoc Cl- do gy ra hin tng bin cc (kh cc hoc u ccha). Ion Ca++ ng vai tr quan trng trong s gii phng cht dn truyn thn kinh.


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2.3. Cc cht dn truyn khc

Trong nhng nm gn y, nhiu nghin cu cho thy rng phn ln cc nron trung ng vngoi bin c cha 2 hoc nhiu cht dn truyn, c th c gii phng ra cng mt lc xinapkhi dy thn kinh b kch thch. Nh vy, h thn kinh thc vt, ngoi acetylcholin (ACh) vnoradrenalin (NA), cn c nhng cht dn truyn thn kinh (neurotransmitters) khc cng cgii phng v c th c vai tr nh cht cng dn truyn (cotransmitters), cht iu bin thnkinh (neuromodulators) hoc chnh n cng l cht dn truyn (transmitters).

Ngi ta tm thy trong tu thng thn, trong cc si thn kinh, trong hch thn kinh thc vthoc trong cc cu trc do h thn kinh thc vt chi phi mt lot cc peptid sau: e nkephalin,cht P, somatostatin, hormon gii phng gonadotropin, cholecystokinin, vasoactive intestinalpeptide (VIP), neuropeptid Y (NPY)... Vai tr dn truyn ca ATP, VIP v NPY trong h thnkinh thc vt dng nh c coi l nhng cht iu bin t c dng ca NA v ACh. Nh vy,bn cnh h thn kinh thc

vt vi s dn truyn bng ACh v NA cn tn ti mt h thng dn truyn khc c gi l dntruyn khng adrenergic, khng cholinergic [Nonadrenergic, non cholinergic (NANC)transmission].

Burnstock (1969, 1986) thy c cc si thn kinh purinergic chi phi c trn ng tiu ha,ng sinh dc- tit niu v mt s mch mu. Adenosin, ATP l cht dn truyn, cc receptorgm receptor adenosin (A hoc P1) v receptor ATP (P2). Cc di typ receptor u hot ngthng qua protein G, cn receptor P2x li thng qua knh ion (Fredholm v cs, 1994).Methylxantin (cafein, theophylin) l cht c ch cc receptor ny.

Nitric oxyd cng l mt cht dn truyn ca h NANC c tc dng lm gin mch, gin phqun. Nitric oxyd c ni m thnh mch, khi c gii phng s hot ha guanylyl cyclase,lm tng tng hp GMPv, gy gin c trn thnh mch.

Cc cht dn truyn thn kinh c tng hp ngay ti t bo thn kinh, sau c lu tr dith phc hp trong cc ht c bit nm ngn dy thn kinh trnh b ph hu. Di tc dngca nhng lung xung tc thn kinh, t cc ht d tr , cht dn truyn thn kinh c giiphng ra di dng t do, c hot tnh tc ng ti cc receptor. Sau chng c thu hi livo chnh cc ngn dy thn kinh va gii phng ra, hoc b ph hu rt nhanh bi cc enzymc bit. Acetylcholin b cholinesterase thu phn, cn noradrenalin v adrenalin th b oxy hav kh amin bi catechol- oxy- methyl- transferase (COMT) v mono- amin- oxydase (MAO).

c bit:

- Dy giao cm i ti tu thng thn khng qua mt hch no c. tu thng thn, dy nytit ra acetylcholin kch thch tuyn tit ra adrenelin. V vy, thng thn c coi nh mthch giao cm khng l.

- Cc ngn dy hu hch giao cm chi phi tuyn m hi ng l phi tit noradrenalin, nhng litit ra acetylcholin.

- Cc dy thn kinh vn ng i n cc c xng (thuc h thn kinh trung ng) cng giiphng ra acetylcholin.

- Trong no, cc xung tc gia cc nron cng nh acetylcholin. Ngoi ra cn c nhng chttrung gian ha hc khc nh serotonin, catecholamin, acid - gama- amino- butyic (GABA)...


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2.4. H thng thn kinh thc vt trong no

Khng th tch ri hot ng ca h thn kinh tr ung ng vi h thn kinh thc vt. Gia 2 hlun lun c mi lin quan cht ch vi nhau m bo tnh thng nht ca c th. Nhng milin quan v ang c tm thy vng di i, h vin (systema limbicus), hi hi m

(hyppocampus), l nhng ni c cc trung tm iu ha thn nhit, chuyn ha nc, ng, m,iu ha huyt p, ni tit, hnh vi...

Trong h thn kinh trung ng cng thy cc cht dn truyn thn kinh v cc receptor nhca h thng thn kinh thc vt ngoi bin.

3. Phn loi theo d-c lNhng thuc c tc dng ging nh tc dng kch thch giao cm c gi l thuc cng giaocm (sympathicomimetic), cn nhng thuc c tc dng ging nh kch thch ph giao cm cgi l thuc cng ph giao cm (para- sympathicomimetic).

Thuc no c tc dng km hm tc dng ca giao cm hay ph giao cm th gi l hu giao cm

(sympathicolytic) hay hu ph giao cm (parasympathicolytic).Nh chng ta thy, hot ng ca thn kinh l nh nhng cht trung gian ha hc, cho nncch phn loi v gi tn theo gii phu v sinh l khng ni ln c y v chnh xc tcdng ca thuc. V vy, mt cch hp l hn c, ng v phng din dc l, ta chia h thnkinh thc vt thnh 2 h: h phn ng vi acetylcholin, gi l h cholinergic (gm cc hch giaocm, ph giao cm; hu hch ph giao cm; bn vn ng c vn; mt s vng trn thn kinhtrung ng) v h phn ng vi adrenalin, gi l h adrenergic (ch gm hu hch giao cm)

Phn loi cc thuc tc dng trn h thng thn ki nh thc vt

Cc thuc tc dng trn h thn kinh thc vt cng mang tnh c hiu, tc dng chn lc trncc receptor ring i vi chng.

Cc receptor ca h cholinergic cn c chia lm 2 loi:- Loi nhn cc dy hu hch (v d tim, cc c trn v tu yn ngoi tit) cn b kch thch bimuscarin v b ngng hm bi atropin, nn c gi l h cm th vi muscarin (hay h M).

- Loi nhn dy tin hch cn b kch thch bi nicotin, nn cn c gi l h cm th vinicotin (hay h N), h ny phc tp, bao gm cc hch giao cm v ph giao cm, tu thngthn, xoang ng mch cnh (b ngng hm bi hexametoni), v bn vn ng c vn thuc hthn kinh trung ng (b ngng hm bi d - tubocurarin).

Cng trn nhng c s tng t, cc receptor ca h adrenergic c chia lm 2 loi: alpha ()v beta ().

Cc thuc kch thch c th tc ng theo nhng c ch:. Tng cng tng hp cht dn truyn thn kinh

. Phong to enzym phn hu cht dn truyn thn kinh

. Ngn cn thu hi cht dn truyn thn kin h v ngn dy thn kinh.

. Kch thch trc tip cc receptor


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Dn truyn xinap thn kinhngoi bin

Trung gian acetylcholin Trung gian noradrenalin(cholinergic) (adrenergic)

H muscarinic(M) H nicotinic (N)

Hu hch ph Hch thc vt C vn Hu hch giao cmgiao cm

Receptor Receptor

Cc thuc c chc th l:

- Ngn cn tng hp cht dn truyn thn kinh

- Ngn cn gii phng cht dn truyn thn kinh

- Phong to ti receptor.

Cu hi t l-ng gi1. Trnh by c im gii phu v chc phn sinh l ca h giao cm v ph giao cm.

Phn bit h cholinergic (M,N) v h adrenergic v gii phu v dc l.

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Bai 04 - Dai cuong va phan loai he than kinh thuc vat [bacsihoasung.wordpress.com].pdf