Exam 4 Study Guide Anatomy and Physiology I PDF

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VERY in depth notes on absolutely everything covered in the lectures regarding exam 4. Covers the CNS, PNS, and everything related. ...

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1. Li stt hest r uct ur aldi vi si onsoft hener voussys t em. Cent r alner voussys t em ( CNS) : 

Br ai nands pi nalcor d( dor salbodycavi t y)

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I nt egr at i onandcommandcent er

Per i pher alnerv oussyst em ( PNS) : 

Pai r edspi nalandcr ani alner v es

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Car r i esmessagest oandf r om t hespi nalcor dandbr ai n

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Consi s tmai nl yofaxons

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Connec tal lt hebodyt oCNS

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Ther ear et wof unct i onaldi vi si ons: o Sensor y( oraffer ent=“ car r yi ngt owar ds” )di vi si on 

Somat i caffer entfiber–car r yi mpul sesf r om ski n,skel e t al muscl es,j oi nt s,ands peci alsensest ot hebr ai n

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Vi scer alaffer entfiber s–t r ansmi ti mpul sesf r om vi scer alor gans t ot hebr ai n

o Mot or( oreffer ent=“ car r yi ngaway” )di vi si on 

Tr ansmi t si mpul sesf r om t heCNSt oeffec t oror gans( muscl es andgl ands)

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i i .Twomai npar t s: 

Somat i cner voussys t em ( SNS) o Vol unt ar y o Composedofsomat i cmot ornervefiber s( axons) o Conductf r om CNSt os kel et almusc l es o Consci ouscont r olofskel et almusc l es( vol unt ar y)

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Aut onomi cner voussyst em ( ANS) o I nv ol unt ar y o Consi s tofvi scer alner vefiber s o Regul at essmoot hmuscl e,car di acmuscl e,and gl ands

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o Di vi si ons:sympat he t i candpar asympat he t i c 2. Descr i bet het ypesofgl i alcel l s,t hei rf unct i on,andl ocat i oni nt henervous syst em. Thet womai nce l lt ypesoft henerv oussyst em ar et heneur ogl i a( gl i alce l l s)andt he neur ons. Neur ogl i a:  Mor eabundantt hanneur ons  Char act er i st i cs:nonneur onal ,nonexci t abl e Neur ogl i acel l si nt heCNS:  Ast r ocyt es( meani ng“ st arce l l s” ) : o Theseast r ocyt esar et hemostabundant ,ver sat i l e,andhi ghl ybr anched gl i alcel l s o Theyc l i ngt oneur onsandt heneur on’ ssynapt i cendi ngs,andt heycover capi l l ar i es o Func t i ons:Suppor t i ngneur ons,anchor i ngneur onst ot hei rnut r i ent suppl i es,andcont r ol l i ngt hechemi calenvi r onmentbyr egul at i ngt hei oni c composi t i onoft heCNS’ext r ace l l ul arflui d  Mi cr ogl i a: o Thesear ephagocyt est hatmoni t ort heheal t hofneur ons( al socal l ed “ br ai nmacr ophages” ) o Theyc l eanupmi cr oor gani smsordeadnervecel ldebr i s  Ependymalcel l s: o Thesecel l sl i net hecent r alcavi t i esoft hebr ai nandspi nalcol umn o Manyoft hem ar eci l i at edandhel pt oci r cul at et hecer e br ospi nalflui d  Ol i godendr ocyt es: o Thesear ebr anchedcel l st hatwr apt heCNSnerv efiber s o Theypr oducemye l i nsheat hs( ori nsul at i ngcover i ngs)ar oundt heaxon Neur ogl i acel l si nt hePNS: 

Schwannce l l s: o Thesecel l ssur r oundt hefiber soft hePNS o Theyf or m myel i nsheat hs

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Sat el l i t ece l l s: o Sat el l i t ece l l sar el ocat edar oundt heneur onsi nt hespi nalcor d( dor sal r ootgangl i on) ,t heaut onomi cgangl i a,andSchwannce l l s. o Theyar et houghtt oactasast r ocyt esi nt hePNS

3. Di scusst heanat omyofaneur on,andt hef unct i on ofeach st r uct ur e. * Not e:Neur onsar ecomposedofce l lbodi es,pr ocesses,andaxons. Neur ons: 

The structural and functional units of the nervous system

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There are around 100 billion neurons

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They are long-lived (with good nutrition – over 100 years)

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They have no centrioles, meaning they are amitotic (except the olfactory epithelium and stem cells in the hyppocampus)

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High metabolic rate

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Their plasma membrane functions mainly in electrical signaling

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They are composed of: 

Cell bodies1. A cell body contains the nucleus and a nucleolus 2. It is the major biosynthetic center which has well-developed Nissl bodies 3. It is also the focal point for the outgrowth of neuronal processes and it contains an axon hillock 4. Most neuron bodies are located in the CNS or vertebral column for protection (i.e. To protect them) 5. A collection of cell bodies within the CNS is called a nucleus, while in the PNS it is called a ganglion.

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Processes1. Processes are arm-like extensions from the cell body of all neurons 2. There are two types of processes; dendrites, and axons. 3. Dendrites are short and branched in most neurons. They receive the signals from other neurons. They also provide an enormous surface area for receiving signals

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Axons1. Axons are structures of the neuron. 2. They are one process that arises from the hillock (axon hillock) 3. Long axons are called nerve fibers 4. The branched end of an axon is called the axon terminal. It is not unusual for there to be 10,000 branches 5. A bundle of axons in the CNS are called a tract, and in the PNS are called nerves 6. Functions to generate and transmit action potentials, and secrete neurotransmitters from the axonal terminals.

4. Descr i bet heanat omyandf unct i on oft hemyel i n sheat h,anddi ffer ent i at e bet weenmyel i nat edandunmyel i nat edneur ons.Cont r astmyel i nat i on i n CNS andPNS.  Myelin Sheath1. The myelin sheath is a whitish, fatty (protein lipid) sheath that wraps around most long axons 2. This sheath surrounds a bundle of axons in the CNS, creating one tract 3. It surrounds a bundle of axons in the PNS, creating one nerve 4. The myelin sheath functions to; protect the axon, electrically insulate fibers from one another, and increase the speed of nerve impulse transmission a. Myelin sheath formation within the PNSo The myelin sheath is formed in the PNS by Schwann cells o Here, the sheath encloses the axon within its plasma membrane o This sheath is concentric layers of membrane o In the PNS, the myelin sheath is covered by neurilemma, which is the remaining nucleus and cytoplasm of a Schwann cell b. Myelin sheath formation within the CNSo Oligodendrocytes form the myelin sheath within the CNS o The sheaths function within the CNS is the same here as it is in the PNS- to enclose the axon within the myelin sheath’s plasma mm o There is no neurilemma covering the sheath within the CNS

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Nodes of Ranvier (Neurofibral Nodes)1. Nodes of Ranvier are gaps in the myelin sheath located between adjacent Schwann cells and the space between the oligodendrocytes sheaths 2. They produce salutatory conduction 3. They are located where voltage-gated Na+ channels are concentrated

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Unmyelinated Axons1. These are axons that do not have a myelin sheath 2. A Schwann cell surrounds nerve fibers, but coiling does not take place (i.e. the Schwann cell will not produce a myelin sheath, but instead, it will surround the nerve fibers itself) 3. Unmyelinated axons provide protection to small diameter axons 4. These axons have no saltatory conduction

5. Cont r astuni pol ar ,bi pol ar ,andmul t i pol arneur onsst r uct ur al l y.I ndi cat ewher e each i smostl i kel yt obef oundandl i nkt hel ocat i ont oi t sf unct i on. Neur onsar ec l assi fiedast hr eet ypes:uni pol arneur ons,bi pol arneur ons,and mul t i pol arneur ons Uni pol arneur ons Theseneur onshaveasi ngl e,shor tpr ocess  Theyar esensor yneur ons  Uni pol arneur onst r ansmi ti mpul sest owar dst heCNS  Foundi nt hel owerext r emi t i es( ex:s pi nalcor d) Bi pol arneur ons Theseneur onshavet wopr ocesses( anaxonpr ocessandadendr i t e pr ocess)  Theyar er ar eneur onswhi char ef oundi nbot ht heeye’ sr e t i naandt he ol f act or ymucosa yneur ons  Theyar esensor  Theyal sot r ansmi ti mpul sest owar dst heCNS Mul t i pol arneur ons Theseneur onshavet hr eeormor epr ocesses( t hesepr oc essesar et he ext ensi onsf r om t hecel lbody)  Theyar et hemostcommont ypeofneur onsi nhumans( maki ngup 99% oft hebody’ sneur ons)  Theyar et hemaj orneur ont ypewi t hi nt heCNS  Mul t i pol arneur onsar emot orneur onsandi nt er neur ons Exam 4_CNS-Fall16

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 Thei rf unct i oni nv ol vescar r yi ngi mpul sesawayf r om t heCNS 6. Definet r act s,nucl ei ,gangl i aandner ves. Tract- a bundle of axons located in the CNS Nerve- a bundle of axons located in the PNS Nuclei- (plural form for nucleus) a collection of cell bodies within the CNS Ganglia- a collection of cell bodies in the PNS 7. Know t hehi st ol ogi caldi ffer encesbet ween gr ayandwhi t emat t er . Gr aymat t eri smost l ycel lbodi esandunmye l i nat edaxons Whi t emat t eri sdensecol l ect i onsofmy el i nat edfiber s 8. I dent i f yhow changesi nmembr anepot ent i al s( gr adedandact i onpot ent i al s) actassi gnal s,andr el at eeach t ypeofsi gnalt ot hegener at i on ofact i on pot ent i al s.( got ot abl edonei n cl ass) * Not e:Depol ar i z at i oni ncr easest hechancesofpr oduci ngact i onpot ent i al s. Repol ar i zat i onr e t ur nst hecel lt oi t sr es t i ngmembr anepot ent i alduet ot he + + t her ei sanabsol ut er ef r ac t or yper i odandar e l at i ver ef r act or y Na –K pump( per i od) .Hyper pol ar i zat i ondecr easest hechancesofpr oduci ngact i onpot ent i al s. Gr adedPot ent i al  Or i gi n:The yar i sei nei t herdendr i t esorcel lbodi es  Typesofc hannel s:Chemi calandmechani cali onchanne l s  Pr opagat i on:Notpr opagat edoverl ongdi st ances  Ampl i t ude:Dependsont hest r engt hoft hest i mul us( nogr eat ert han50mV)  Pol ar i t y:Canbehyper pol ar i z i ng( i nhi bi t or y)ordepol ar i z i ng( exci t at or y)  About : o Gr adedpot ent i al smovei nbot hdi r ect i ons o Theyar eshor t l i v ed,l ocalchangesi nt hemembr anepot ent i al o Thei ri nt ensi t ydecr easeswi t hdi st ance o Thei rmagni t udevar i esdi r ec t l ywi t ht hes t r engt hoft hest i mul us o I fasuffici ent l ys t r ongGPr eachest heaxonhi l l oc k,i tcani ni t i at eAP’ s o Or ,i tcanbehyper pol ar i zi ng,whi c hi nhi bi t st hegener at i onofanAP o I thasachar gedi st ance( ampl i t ude)of50mV( ex:70mVt o20mV) o I tuseschemi calgat edchannel sandmechani calgat edchannel s Act i onPot ent i al  Or i gi n:Ar i semai nl yi nt heaxonhi l l ock Exam 4_CNS-Fall16

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Typesofc hannel s:Vol t agegat edi onchannel s Pr opagat i on:Pr opagat edandcommuni cat edoverl ongdi s t ances Ampl i t ude:Al lornot hi ng( 100mV) Pol ar i t y:Al waysconsi st sofadepol ar i zi ngphasef ol l owedbyar epol ar i zi ng phase About : o Act i onpot ent i al sar eal l or not hi ng o AP’ sexper i enceabr i efr ever saloft hei rmembr anepot ent i alwi t ha t ot alampl i t udeof100mV( 70mVt o+30mv) o Theydonotdecr easei nst r engt hoverdi st ances o AP’ sar i seatt r i ggerz ones( axonhi l l ock)andpr opagat eal ongt heaxon i nonedi r ec t i on o Asnot ed,t hei rpol ar i t yal waysconsi st sofadepol ar i zi ngphase f ol l owedbyar epol ar i z i ngphasebef or er e t ur ni ngt ot her es t i ngmm pot ent i al o Thet ypesofchanne lseeni st hevol t agegat edi onchanne l

9. I dent i f yt heeffect sofaxon di amet erandmyel i nat i on on conduct i on vel oci t y ofaxons. Conduct i onv el oci t i esvar ywi de l yamongneur ons.Ther at eofpr opagat i oni s det er mi nedbyaxondi ame t erandt hepr esenceofmyel i nsheat h. Axondi amet er  Thel ar gert hedi amet er ,t hef ast ert hei mpul se  Lar geraxonsofferl essr esi st ancet ot heflow ofcur r ent ssot hatt he membr anecanbebr oughtt oat hr eshol dqui c ker Pr esenceofmyel i nsheat h Thepr esenceofamye l i nsheat hdr amat i cal l yi ncr easest hespeedof i mpul sesbecausei tact sasani nsul at or( pr event sl eakageofi ons)  Sal t at or yconduct i onoccur smuchf ast er( 30X)al ongmye l i nat edaxonst han i tdoesonunmyel i nat edaxons 10.Defineasynapse Synapsesar econnec t i onsbe t weenneur onst hr oughwhi c h“ i nf or mat i on”flows f r om oneneur ont oanot her . Asynapsesi scomposedoft wot ypesofneur ons:

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Pr esynapt i cneur on Conduct si mpul sest owar dst hesynapse  I st hei nf or mat i onsender  Rel easest heneur ot r ansmi t t er Pos t synapt i cneur on Tr ansmi t si mpul sesawayf r om t hesynapse  I st hei nf or mat i onr ecei v er  Bi ndst heneur ot r ansmi t t er 11.Nameanddescr i bet het wot ypesofsynapses. Ther ear et wovar i e t i esofsynapses: El ec t r i calsynapse Ar el esscommon 

Theyar emor ecommondur i ngdevel opment ,butar el at err epl aced

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El ec t r i calsynapsesusegapj unct i onst oconnectt oeachot her( maki ng t r ansmi ssi onext r aor di nar i l yf as t )

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Sync hr oni z at i onmaybei mpor t anti nf unct i onst hatr equi r e i ns t ant aneousr es ponses,suchasr eflexesandpacemaker s.

Chemi calsynapse Speci al i z edf ort her el easeandr ecept i onofneur ot r ansmi t t er s 

Somer epl aceel ec t r i calsynapsesaf t erdev el opment

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Typi cal l yc omposedoft wopar t s:

o Axont er mi nal soft hepr esynapt i cneur on-cont ai nssynapt i c v esi cl es( whi chcont ai nt housandsofneur ot r ansmi t t er s) o Recept orr egi ons-r egi onsont hedendr i t e( s)orsomaoft he post synapt i cneur on 

Thec hemi calsynapseal sohasasynapt i ccl ef t ,whi chpr ev ent snerv e i mpul sesf r om di r ect l ypassi ngf r om oneneur ont ot henext .The t r ansmi ssi onwhi choccur sacr osst hesynapt i ccl ef ti sachemi calevent t hatensur esuni di r ect i onalcommuni cat i onbet weenneur ons

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Theneur ot r ansmi t t eri sr el easedi nt ot hesynapt i ccl ef t ,t hencr ossest he synapt i ccl ef tandbi ndst or ecept or sont hepost synapt i cneur on

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Thepost synapt i cmembr ane’ sper meabi l i t yt henchanges,causi ngei t her anexci t at or yori nhi bi t or yeffect( post synapt i cpot ent i al )

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wot ypesofpost synapt i cpot ent i al sar ebot hGr aded Pot ent i al s  Thet ( EPSP& I PSP)

EPSP-exci t at or ypos t synapt i cpot ent i al s 

Thi sneur ot r ansmi t t ercausest hemembr anet obecomemor e ar i z at i on per meabl et odepol

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I tcani ni t i at eanact i onpot ent i ali nanaxon

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However ,asi ngl eEPSPneur ot r ansmi t t ercannott r i ggeranAP

I PSP-i nhi bi t or ypos t synapt i cpot ent i al 

Thi sneur ot r ansmi t t ercausest hemembr anet obecomemor e per meabl et ohyper pol ar i z at i on

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I tl eav est hechar geont hei nnersur f acenegat i v e

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I ti nduceshyper pol ar i zat i on,t her ef or er educi ngt hepost synapt i c neur on’ sabi l i t yt opr oduceanAP

EPSP Pol ar i t y Depol ar i z at i on Changei nmm pot ent i al Membr anepot ent i al becomesmor eposi t i ve I onmovement Na+andK+movement occur si nopposi t e di r ect i ons( Ther ei smor e Na+) Changesofpr oduci ngan Chancesofpr oduci ngan AP ac t i onpot ent i ali ncr ease

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I PSP Hyper pol ar i z at i on Membr anepot ent i al becomesmor enegat i v e CI -movesi norK+moves outoft heneur on

Chancesofpr oduci ngan ac t i onpot ent i aldecr ease

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