Biology 12 3B

The Nervous System http://www.youtube. om/w!t h"v#$%7&S'e()*+ 'u, t-o,s of the Nervous System +ses se,sory re eptors to gather sensory input so -t !, monitor h!,ges both -,s-.e !,. outs-.e the bo.y. /t processes and interprets sensory input !,. .e -.es wh!t type of response to e0- -t -, ! pro ess !00e. -,tegr!t-o,. /t !uses ! respo,se1 !00e. motor output1 by activating effector organs su h !s mus 0es or g0!,.s.
Text Ref Pg 372-407

Neuro,s - 2Nerve 3e00s4 %-00-o,s of ,euro,s !re the stru tur!0 u,-t of the ,ervous system h-gh0y spe -!0-)e. e00s th!t o,.u t mess!ges -, the form of e0e tr- !0 -mpu0ses !,. hem- !0 s-g,!0s from o,e p!rt of the bo.y to !,other

5,!tomy of ! Neuro,

Biology 12 3B
Neuro,s !re typ- !00y 0!rge1 omp0ex e00s w-th 3 m!-, p!rts: *6 Cell Body (Soma) contains the nucleus and other cell organelles 7ost !re 0o !te. -, the 3NS where they !re prote te. by the bo,es of the s8u00 !,. vertebr!0 o0um,. Cell bodies that lie along the nerves in the PNS are called ganglia 26 Dendrites the main input or receptive region of the neuron 9e,.r-tes re e-ve s-g,!0s from other ,euro,s !,. se,. them to the e00 bo.y They prov-.e !, e,ormous !mou,t of surf! e !re! for re e-v-,g s-g,!0s from other ,euro,s 36 A on (!a" # a$ay) conducts nerve impulses a$ay from the cell body to$ard other neurons or effectors The .e,.r-tes !,. !xo,s of ! ,euro, !re b!s- !00y tubes o,stru te. of e00 membr!,e1 !00e. a omembrane1 wh- h !re f-00e. w-th ytop0!sm- f0u-. !00e. a oplasm The e0e tro hem- !0 s-g,!0 or -mpu0se th!t !00ows ,euro,s to ommu,- !te tr!ve0s !0o,g the !xomembr!,e 5xo,s !, be very short1 or !, be very 0o,g up to 3 or 4 feet: ; !xo,s of the motor ,euro,s o,tro00-,g the s8e0et!0 mus 0es of your b-g toe exte,. from the 0umb!r reg-o, of your sp-,e to your foot. There !re 3 0!sses of ,euro,s: *6 Sensory neurons 3e00 bo.-es 0-e outs-.e the 3NS -, g!,g0-! %ransmit impulses from sensory receptors in the s&in or internal organs to the CNS Se,sory ,euro,s possess se,sory re eptors th!t !, .ete t h!,ges -, the e,v-ro,me,t e.g. h!,ges -, pressure1 temper!ture1 p<1 et 26 'nterneurons (ie entirely $ithin the CNS bet$een sensory and motor neurons Re e-ve -,put from se,sory ,euro,s !,. !0so from other -,ter,euro,s -, the 3NS !,. tr!,sm-t -t to motor ,euro,s 36 )otor Neurons 3e00 bo.-es 0-e w-th-, the 3NS %a&es messages a$ay from the CNS to an effector =s8e0et!0 mus 0e1 org!,1 or g0!,.6 >ffe tors the, !rry out respo,ses to e,v-ro,me,t!0 h!,ges .ete te. by se,sory ,euro,s -, the PNS.

Biology 12 3B

Biology 12 3B

Tr!,sm-ss-o, of ! Nerve /mpu0se ; through ! ,euro, Neurons e ist in either a resting state* or stimulated state ?he, ! ,euro, -s !.e@u!te0y st-mu0!te.1 !, e0e tr- !0 -mpu0se !00e. !, action potential -s ge,er!te. !,. o,.u te. !0o,g the ,euro, Rest-,g 7embr!,e Pote,t-!0 ?he, ! ,euro, -s NAT tr!,sm-tt-,g !, -mpu0se -.e. whe, -t -s rest-,g1 the -,s-.e of the e00 -s N+,A%'-+(. charged compared to the outside .ue to the prese, e of ,eg!t-ve0y h!rge. prote-,s -, the !xop0!sm of the ,euro, 'or most ,erve e00s the rest-,g pote,t-!0 -s betwee, -BC m( !,. -70m(

Neuro,s .eve0op the-r rest-,g pote,t-!0 be !use:

Biology 12 3B
*6 Neg!t-ve0y h!rge. prote-,s w-th-, the !xop0!sm !re too 0!rge to .-ffuse out of the !xo,1 !,. so they o,tr-bute to the over!00 ,eg!t-ve h!rge -,s-.e ! ,euro,

26 So.-um-pot!ss-um pumps -, the !xomembr!,e use 5TP to m!-,t!-, !, u,eve, .-str-but-o, of -o,s by ! t-ve tr!,sport Th-s pump pushes two pot!ss-um -o,s =2 DE6 -,to the !xop0!sm for every three so.-um -o,s =3 N!E6 -t pumps out of the !xop0!sm

5 t-o, Pote,t-!0s Action potentials are said to be !all" or !none" responses to stimuli /hen threshold potential is reached (011m-) the distribution of charges on each side of the a omembrane changes (Na2 ions flo$ into the a oplasm) St-mu0- th!t !re ,ot suff- -e,t e,ough to re! h thresho0. pote,t-!0 .o ,ot resu0t -, the f-r-,g of !, ! t-o, pote,t-!0. Steps of !, 5 t-o, Pote,t-!0 *6 A neuron receives a stimulus ?he, ! rest-,g ,euro, -s st-mu0!te. vo0t!ge g!te. N!E h!,,e0s ope, !,. N!E beg-,s to f0ow -,to the !xo, of ! ,euro,. If a stimulus is strong enough1 e,ough N!E w-00 f0ow -,to the ,euro, to r!-se -ts membr!,e pote,t-!0 from -ts resting potential of 034m- to -ts threshold potential of 011 m-

26 Depolari5ation 2+psw-,g of the 5 t-o, Pote,t-!04 A, e thresho0. pote,t-!0 -s re! he. =-CCm(61 !, ! t-o, pote,t-!0 -s -,-t-!te. !,. r!p-. .epo0!r-)!t-o, o urs 9ur-,g .epo0!r-)!t-o, vo0t!ge g!te. so.-um h!,,e0s ope, !,. N!E rushes -,to the !xo,1 r!p-.0y -, re!s-,g the membr!,e pote,t-!0 from -CCm( E40 m(. 36 6epolari5ation 29ow,sw-,g of the 5 t-o, Pote,t-!04 /mme.-!te0y !fter !, ! t-o, pote,t-!0 -s f-re.1 repo0!r-)!t-o, o urs N!E h!,,e0s beg-, to 0ose !,. the ,et -,f0ux of N!E stops omp0ete0y DE h!,,e0s ope, !,. there -s ! ,et f0ow of DE out of the !xo, 5s ! resu0t the !xop0!sm be omes more ,eg!t-ve !g!-, =E40 m( -70m(6

Biology 12 3B
46 6efractory (6ecovery) Period 2+,.ershoot4 9ur-,g the refr! tory per-o. the rest-,g pote,t-!0 -s re-est!b0-she.. DE g!tes !re s0ow to 0ose !,. !s ! resu0t ex ess-ve DE 0e!ves the !xop0!sm !us-,g ! tempor!ry 2u,.ershoot4 where the membr!,e pote,t-!0 be omes more ,eg!t-ve th!, .ur-,g rest-,g st!te. Aver t-me N!E/DE pumps restore -o, gr!.-e,ts b! 8 to -70 m( !s -, the rest-,g st!te. /, the refr! tory per-o.1 N!E h!,,e0s !re -,! t-v!te. !,. so the ,euro, !,,ot respo,. to !,y ,ew st-mu0-. <omeost!t/mb!0!, e

5 ,umber of hem- !0 !,. phys- !0 f! tors -,h-b-t or -mp!-r the prop!g!t-o, of ,erve -mpu0ses. 50though the-r me h!,-sms of ! t-o, .-ffer1 !0 oho01 se.!t-ves1 !,. -,&e te. !,esthet- s !00 b0o 8 ,erve -mpu0ses by re.u -,g membr!,e perme!b-0-ty to -o,s1 m!-,0y N!E. 5s we h!ve see,1 ,o N!E e,try -,to the !xop0!sm # ,o ! t-o, pote,t-!0 ge,er!t-o,

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<omeost!t-

/mb!0!, e ; Pufferf-sh Tetro.otox-,

Tetro.otox-,1 fre@ue,t0y !bbrev-!te. !s TTF1 -s ! pote,t ,eurotox-, w-th ,o 8,ow, !,t-.ote. TTF b0o 8s ! t-o, pote,t-!0s -, ,erves by b-,.-,g to the vo0t!ge-g!te.1 f!st so.-um h!,,e0s -, ,erve e00 membr!,es1 esse,t-!00y preve,t-,g !,y !ffe te. ,erve e00s from f-r-,g. The b-,.-,g s-te of th-s tox-, -s 0o !te. !t the pore ope,-,g of the vo0t!ge-g!te. N!E h!,,e0. The f-rst re or.e. !ses of TTF po-so,-,g were from the 0ogs of 3!pt!-, $!mes 3oo8 from *774. 3oo8 re or.e. h-s rew e!t-,g some 0o !0 trop- f-sh =pufferf-sh61 the, fee.-,g the rem!-,s to the p-gs 8ept o, bo!r.. The rew exper-e, e. ,umb,ess !,. short,ess of bre!th1 wh-0e the p-gs were !00 fou,. .e!. the ,ext mor,-,g. " /, h-,.s-ght1 -t -s 0e!r th!t the rew re e-ve. ! m-0. .ose of tetro.otox-,1 wh-0e the p-gs !te the pufferf-sh bo.y p!rts th!t o,t!-, most of the tox-,1 thus be-,g f!t!00y po-so,e..

Biology 12 3B
Tr!,sm-ss-o, 5 ross ! Sy,!pse ; from o,e ,euro, to !,other >very !xo, br!, hes -,to m!,y f-,e e,.-,gs =*000 - *010006 !,. e! h -s t-ppe. by ! sm!00 swe00-,g !00e. !, !xo, term-,!0 +ach a on terminal lies very close to the dendrite or cell body of another a on ho$ever* they D7 N7% physically touch %his region of close pro imity is called a synapse and the space bet$een t$o neurons is called the synaptic cleft 5t ! sy,!pse1 the first neuron is called the presynaptic neuron1 !,. the ne t neuron is called the postsynaptic neuron

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tr!,sm-ss-o, of -,form!t-o, from o,e ,euro, to !,other ! ross ! sy,!pt- 0eft -s usu!00y !rr-e. out by hem- !0s !00e. neurotransmitters /,s-.e the !xo,s of ,euro,s1 ,eurotr!,sm-tters !re store. -, membr!,e bou,. 2p! 8!ges4 !00e. synaptic vesicles Neurotr!,sm-tters ! t !s hem- !0 messe,gers th!t .e0-ver ex -t!tory or -,h-b-tory mess!ges from o,e ,euro, to the ,ext

Biology 12 3B Process of the %ransmission %ravelling across the Synapse

*6 ?he, !, ! t-o, pote,t-!0 !rr-ves !t !, !xo, term-,!0 of ! presy,!pt- ,euro,1 g!te. h!,,e0s for !0 -um -o,s =3!2E6 ope,1 !,. !0 -um f0oo.s -,to the !xo, term-,!0 26 Th-s -,f0ux of 3!2E !uses sy,!pt- ves- 0es !rry-,g ,eurotr!,sm-tters to m-gr!te to1 !,. fuse w-th1 the presy,!pt- membr!,e 36 The ves- 0es the, re0e!se the-r o,te,ts v-! exo ytos-s -,to the sy,!pt0eft 46 The ,eurotr!,sm-tters the, .-ffuse ! ross the sy,!pt- 0eft !,. reversibly b-,. to spe -fre eptor prote-,s o, the p0!sm! membr!,e of ! postsy,!pt- ,euro, + citatory neurotransmitters !use N!E to f0oo. -,to the .e,.r-te of the postsy,!pt,euro, ; th-s h!,ge -, membr!,e pote,t-!0 .r-ves the ,euro, 0oser to !, ! t-o, pote,t-!0. 'nhibitory neurotransmitters pro.u e ! s-g,!0 th!t .r-ves the postsy,!pt- ,euro, f!rther from !, ! t-o, pote,t-!0 by -,h-b-t-,g tr!,sport of N!E -,to -ts !xo, C6 A,0y ! fr! t-o, of ! se o,. !fter ,eurotr!,sm-tters b-,. to the-r re eptors o, the postsy,!ptmembr!,e1 they !re re0e!se. b! 8 -,to the sy,!pt- 0eft /, some sy,!pses the postsy,!pt- membr!,e o,t!-,s e,)ymes th!t r!p-.0y bre!8.ow, !,. -,! t-v!te ,eurotr!,sm-tters Neurotr!,sm-tters !, !0so be t!8e, up !,. re y 0e. or bro8e, .ow, by the !xo, term-,!0 they were re0e!se. from =presy,!pt- membr!,e6 o, e they h!ve .o,e the-r &ob %he short e istence of neurotransmitters in a synapse prevents continuous stimulation or inhibition of postsynaptic membranes

Neuro,s !,. how they wor8 =!0so s!ve. -, Re!06

Arg!,-)!t-o, of the Nervous System

Biology 12 3B

The ,ervous system h!s 2 m!&or .-v-s-o,s: *6 Central Nervous System (CNS) o 3o,s-sts of the br!-, G sp-,!0 or. o The -,tegr!t-o, !,. omm!,. e,ter of the ,ervous system o /,terprets se,sory -,put !,. .- t!tes motor respo,ses b!se. o, p!st exper-e, es1 ref0exes !,. urre,t o,.-t-o,s 26 Peripheral Nervous System (PNS) 3o,s-sts m!-,0y of the ,erves =bu,.0es of !xo,s6 th!t exte,. from the br!-, !,. sp-,!0 or. of the 3NS o 3* p!-rs of sp-,!0 ,erves !rry -,fo to !,. from the sp-,!0 or. = erv- !01 thor! - 1 0umb!r1 s! r!01 o yge!06. o *2 p!-rs of r!,-!0 ,erves !rry -,fo to !,. from the br!-,. These ,erves: *6 3!rry se,sory mess!ges to the 3NS 26 3!rry motor omm!,.s from the 3NS to the mus 0es !,. g0!,.s Peripheral nerves serve as the communication lines that lin& all parts of the body to the CNS

Per-pher!0 Nervous System =PNS6 3!, be .-v-.e. -,to: *6 Somatic Nervous System !-oluntary Nervous System" 3o,.u ts -mpu0ses from the 3NS to s8e0et!0 mus 0es.

Biology 12 3B
Through the som!t- ,ervous system we !, consciously o,tro0 our s8e0et!0 mus 0es 26 Autonomic Nervous System (ANS) !'nvoluntary Nervous System" 3o,s-sts of v-s er!0 motor ,erve f-bers th!t regu0!te the ! t-v-ty of smooth mus 0es1 !r.-! mus 0es1 !,. g0!,.s. P0!ys ! ro0e -, mov-,g foo. through the .-gest-ve tr! t1 pump-,g b0oo. through the he!rt1 re0e!s-,g se ret-o,s from g0!,.s1 bre!th-,g1 et . The 5NS h!s 2 fu, t-o,!0 sub.-v-s-o,s: !6 Parsympathetic Division !6est 8 Digest" nervous system o 2<ouse8eeper4 or 2veget!t-ve4 system o Promotes all internal responses associated $ith being in a rela ed state -.e. s!0-v!t-o,1 .-gest-o,1 ur-,!t-o,1 .efe !t-o,1 ry-,g1 et . b6 Sympathetic Division !9ight or 9light" nervous system o The f-ght or f0-ght respo,se -s ! t-v!te. whe, our br!-, per e-ves se,sory -,put =-.e. ! st-mu0us6 !s ! thre!t o ?e be ome !0ert !,. !tte,t-ve to our e,v-ro,me,t o The 2stress hormo,es4 !.re,!0-,e1 ,or!.re,!0-,e !,. ort-so0 !re re0e!se. from the !.re,!0 g0!,.s =o, top of the 8-.,ey6 -,to our b0oo.stre!m o The bo.y respo,.s by: !. -, re!s-,g he!rt r!te b. tr-gger-,g the re0e!se of g0u ose from g0y oge, -, the 0-ver . w-.e,-,g !-r p!ss!gew!ys !,. -, re!s-,g bre!th-,g r!te .. .-0!t-,g the pup-0s to m!x-m-)e v-su!0 !0ert,ess e. !0ter-,g b0oo. f0ow p!tter,s ; re.u -,g b0oo. f0ow to surf! e t-ssues !,. .-gest-ve system !,. -, re!s-,g b0oo. f0ow to the s8e0et!0 mus 0es f. .e re!s-,g s!0-v!ry se ret-o, !,. te!r pro.u t-o, g. -,h-b-ts the b0!..er o,tr! t-o,s !,. ev! u!t-,g the o0o, %he parasympathetic and sympathetic divisions of the nervous system typically $or& in opposition to each other ; wh!t o,e sub.-v-s-o, st-mu0!tes1 the other -,h-b-ts

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Biology 12 3B

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