Ch. 7 PNS - Efferent Division PDF

Preview

Summary

chapter 7: efferent division, class lecture notes...

Description

Cha pt e r7PNS:Effe r e ntDi vi s i on

Par a s y mpa t he t i c( Cr a ni o s a c r a l )Ne rSys . : 1 s tn e ur o n( p r e g a n g l i o n i c )=l o n ga x o n ; Ce l lb o d yi nCNSwh i l ea x o nt r a v e l st ot i s s u e . 2 n dn e u r o n( p o s t g a n gl i on i c )=s h o r ta x o n . Ce l lb o d ya to rne a rt a r g e tt i s s u e . NTo fpr ea ndpo s t g a ng l i o ni cfibe r=a c e t y l c ho l i ne( ACh) ho l i ne r g i cfib e r s( a x o n s ) ; AChi sr e l e a s e db yc No t i c eh o wma n yo r g a n sa r ei n n e r v a t e db yCr a n i a ln e r v eX( t heVa g u sn e r v e ) . Sy mpa t he t i c( Tho r a c o l umba r )Di vi s i o n( fig4 3 2 1 ) 1 s tn e u r o n( p r e g a n g l i o n i c )=s ho r ta x o n ; Ce l lb o d yl o c a t e di ni n t e r me d i o l a t e r a l( I ML)s p i n a lc o r d( a k a“ l a t e r a lh o r n ” )i nT1– L2r e g i o no fs p i na l c or d ; a x o nt r a v e l st oc ha i ng a n g l i o nn e a rs pi n a lc o r d . n d 2 n e u r o n( p o s t g a n g l i on i c )=l o n ga x o n. Ce l lb o d yi nc h a i ng a n g l i o nwh i l ea x o nt r a v e l st ot i s s u e . Ne ur o t r a ns mi t t e r( NT)o fpr e g a ng l i oni cfibe r=Ac h;a ndNTo fpo s t g a ng l i o ni cfibe r=no r e pi( s e e fig4 3 2 2 ) No r e p i n e ph r i n e( NE)i sp r i ma r yn e u r o t r a n s mi t t e rr e l e a s e db ya dr e ne r gi cfib e r s( a x o n s ) . Ad r e n a lme d u l l ai samo d i fie dp a r to fs y mp a t h e t i cn e r v o u ss y s t e m Mo d i fie ds y mpa t he t i cg a n g l i o nt ha td o e sn o tg i v er i s et op o s t g a n g l i o n i cfib e r s St i mu l a t i o no fp r e g a n g l i o n i cfib e r s e c r e t i ono fh o r mo ne si n t ob l o o d Ab o u t2 0 %o fh o r mo n er e l e a s ei sno r e pi ne phr i ne[ t hi n k :n o r e p i n e p h r i n e–N–Ne u r ot r a n s mi t t e r– p r i ma r i l yr e l e a s e da sn e u r o t r a n s mi t t e ri ns yn a p t i cc l e f t ] Ab o u t8 0 %o fh o r mo n e( r e l e a s e di n t ob l o o d )r e l e a s e di se pi ne phr i ne( a d r e n a l i ne )[ t h i n k :e p i n e p h r i n e– E–En d o c r i n e–r e l e a s e di n t obl o o d ] Ad r e n e r g i cr e c e p t o r Bo u n db yn or e p i n e p hr i nea nde p i n e p h r i n e Al p har e c e p t o r s Al p ha1r e c e pt o r s Be t ar e c e p t o r s Be t a1r e c e p t o r s Be t a2r e c e p t o r s Be t a3r e c e p t o r s( o nl i p i dt i s s u e ) Ex . be t ab l o c k e r s–b e t ar e c e p t or sa r ep r i ma r i l yo nt heh e a r t . S owh e ns o me o n ewi t hh i g hBPi st a k i n g b e t ab l o c k e r s , b e t ar e c e p t o r sa r eb l o c k e d–me an i n gs y mp a t h e t i cn e r v o u ss y s t e mwo n ’ tb ea b l et o i n fl u e n c et h eh e a r t( won ’ ti n c r e a s eh e a r tr a t e wo n ’ ti nc r e a s eBP Ne ur o r e c e pt or so fANS Ac e t y l c ho l i n e( Cho l i ne r g i c )r e c e p t or s[ b i n dt oAc h ] n i c o t i n i cr e c e pt o r s[ a c t i v a t e db yn i c o t i n e ]–f o u n do nt h ep o s tg a n g l i o n i cn e u r o no ft h ePNS. [ a n d mu s c l efib e r s ] mu s c a r i n i cr e c e p t o r sa c t i v a t e db ymu s hr o o mp o i s o nmu s c a r i n e ]–f o u n do nt h ee ffe c t o rt i s s u e so ft h e PNS,[ e ffe c t o rc e l lme mb r a ne s( s mo o t hmu s c l e , c a r d i a cmu s c l e ,g l a n d s ) ] Ad r e ne r g i cr e c e p t o r s( f o re p i n e p h r i n ea n dno r e p i n e p h r i n e ) Bo u n db yNEa ndEPI&me d i a t et h eSNSr e s po n s e .

Loc a t e dont het a r g e tt i s s ueo ft h eSNSp a t h wa y s a l p h a a l p h a1r e c e p t o r s a l p h a2r e c e p t o r s b e t a b e t a1r e c e p t o r s… a b b r e vi a t e d“ ®” b e t a2® b e t a3® Ev e r y t hi ngt ha tc o me so uto ft hes pi na lc o r dma ke sACha ndr e l e a s e si t ,a ndt ha tAChbi ndst o t heni c o t i ni cr e c e pt o r . e ne r g i c( ma ke s s ympa t he t i cne r v o uss ys t e m:t hepo s t g a ng l i oni cne ur o nofs y mpa t he t i cNSi sAdr o rr e l e as e sa dr e nal i ne=e pio rno re pi ) . Go e st oal phao rbe t ar e c e pt o rde pe ndi ngo nwhe r ei t s g o i ng pa r as y mpa t he t i cne r v ouss y s t e m:po s t g a ng l i o ni ci sCho l i ne r g i c( ma ke sa ndr e l e a s e sAc h) , ho we v e ri tbi ndst oaMus c a r i ni cr e c e pt o r( whi c hha si t si nflue nc eo ni t st a r g e tt i s s ue ) . Adr e ne r g i c–wi l ls pe e dup( e x . he a r tr a t e ) Mus c a r i ni c–wi l ls l o wdo wn( e x . he ar tr a t e ) So ma t i cn e r v o u ss y s t e m Mo t o rn e u r o n s mo t orn e ur o n so r i g i n a t ei ns p i n a lc o r d( v e nt r a lh o r n )orb r a i ns t e ma n de n do ns k e l e t a lmu s c l e r e l e a s e sn e u r ot r a n s mi t t e r , a c e t y l c h o l i n e( Ac h) ,wh i c hs t i mu l a t e smu s c l ec o nt r a c t i o n( n i c o t i n i cr e c e p t o r ) =fin a lc o mmo np a t h wa yb ywh i c hv a r i o u sr e g i o n sofCNSe x e r tc on t r o lo v e rs k e l e t a lmus c l ea c t i v i t y Th e s ea r e a so fCNSi n c l u d es p i n a lc o r d , mo t o rr e g i onso fc o r t e x , b a s a ln u c l e i , c e r e b e l l u m,a n db r a i n s t e m Ne u r o mus c u l a rj u n c t i o n Th eNe u r o mu s c ul a rJ u n c t i o n( NMJ )a n dEl e c t r o me c h a n i c a lCo u p l i n g( l i n ki n ge l e c t r i c i t yi nt h en e u r o n t ome c h a ni c a lmo v e me nti nt h emu s c l e ) NMJ=Sp e c i a l i z e dn e u r o na ls y n a p s ef o u n do n l yons ke l e t a lmus c l e Ev e n t s Ax o nt e r mi n a lo fmo t o rn e u r o nf o r msne ur o mu s c u l a rj u nc t i o nwi t has i n g l emu s c l ec e l l Si g n a l sa r ep a s s e db e t we e nn e r v et e r mi n a la ndmu s c l efib e rb yme a n sofn e u r o t r a n s mi t t e rAc h Re l e a s e dAChb i n d st or e c e p t ors i t e so nmo t o re n dpl a t eo fmus c l ec e l lme mb r a n e Bi n d i n gt r i g g e r so p e n i n go fs p e c i ficc ha n ne l si nmo t o re ndpl a t e I o nmo v e me n t sd e po l a r i z emo t o re n dp l a t e , p r o du c i n ge n d p l a t ep o t e n t i a l Loc a lc u r r e n tflo wb e t we e nd e p o l a r i z e de n dp l a t ea n da d j a c e ntmu s c l ec e l lme mb r a n eb r i n g sa d j a c e n t a r e a st ot h r e s h o l d Ac t i o np o t e n t i a li si n i t i a t e da n dp r o pa g a t e dt h r o u gh o u tmu s c l efibe r Si mi l a r i t i e st on e u r a ls y n a p s e Exa c ts a mes e q u e n c eo fe v e n t sa si nn e u r o n n e u r o ns y n a p s ee x c e p t : On l yAc hi sus e d Th ep os ts y n a p t i cme mb r a n ea c t i o np o t e n t i a lg e n e r a t e dd e p o l a r i z e smu s c l en o tn e u r a lt i s s u e .

Ac e t y l c hol i ne s t e r a s ei sa ne nz y met h a tb r e a k sd o wna c e t y l c h o l i n e( Ac h )i nt h es y n a p s ea n dh e l pss t o p I fy o ur e mo v eAc e t y l c h o l i n e ,y ous t o pmu s c l ec o n t r a c t i on ] mu s c l ec on t r a c t i on .[ I n a c t i v a t e sAc h e nd se nd p l a t ep o t e n t i a la n dt h ea c t i o np o t e n t i a la ndr e s u l t a n tc o nt r a c t i o n .

Sympa t h e t i cSt i mul a t i o n No r e p i n e p h r i n e

Ep i n e p h r i n e

u r c e :Ad r e n a lme d u l l a So u r c e :p o s t g a n gl i o n i cs y mp a t h e t i cn e r v e So fib e r s Effe c t sl a s t3 0s e c o n d so rmor e Effe c t sl a s taf e ws e c o n d s

Co mb i n ewi t ha l phar e c e pt o r s ( o p e ns o d i u mc ha n ne l s )

Co mb i n ewi t hbe t ar e c e p t o r s

Co n s t r i c tp e r i ph e r a lbl o o dv e s s e l s

I n c r e a s eh e a r tr a t e

Co n s t r i c td i g e s t i v es y s t e ms p h i n c t e r s

Di l a t ec o r o n a r ya r t e r i e s I n c r e a s er e s p i r a t o r yr a t e Di l a t eb r on c h i o l e s Di l a t ep e r i p he r a lb l o o dv e s s e l si nmu s c l e s I n c r e a s er e l e a s eofg l u c o s ef r o ml i v e r I n c r e a s eb r e a k d o wno ff a t...