peripheral nervous system - weebly · 2019. 10. 26. · peripheral nervous system lesson 15....
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PeripheralNervousSystemLesson15
LearningGoals
1. Beabletodistinguishbetweentheafferentandefferentsystem
2. Beabletodistinguishbetweenthesomaticandautonomicsystem
3. Beabletodistinguishbetweenthesympatheticandparasympatheticsystem
PeripheralNervousSystem(PNS)
•Regulatesmovement(skeletalmuscles)andinternalenvironmentofthebody(organs)•CarriesinformationbetweenthebodyandtheCNS
Division
PNSisdividedinto:1. Theafferentsystem• Receivesinformationfromsensoryreceptors• Transmits informationtotheCNS
2. Theefferentsystem• Carries signalsfromtheCNStoeffectors (i.e.musclesandglands)
EfferentSystem
Efferentsystemismadeupaxonsthatcarrysignalstoeffectors
Furthersubdividedinto:1. Thesomaticsystem• Communicateswithskeletalmuscles
2. Theautonomicsystem• Communicateswiththesmoothmusclesandglands
Somaticsystem
ControlsbodymovementsandcarriessignalsfromtheCNStotheskeletalmuscles
31pairsofspinalnerves:•8cervical•12thoracic•5lumbar•5sacral
•1coccygeal
Somaticsystem
Eachservesdifferentpartsofthebody:
• Cervical– head,neck,arms,somebackmuscles• Thoracic – chestandabdomen• Lumbar– legs• Sacral– bowel,bladder,andsexorgans• Coccygeal– rectumandanus
Spinalcord
• Ventralroots relaymotorinformationfromtheCNS
• Fromthespinalcord,dorsalroot carriessensoryinformationtotheCNS
Autonomicsystem
• Workswithendocrinesystemtoregulatethebodyinresponsetochangesintheinternalandexternalenvironment
• Alwaysactive!à Largelyinvoluntaryprocesses• 2brancheshaveopposingfeatures:
1. Sympathetic– “fightorflight”• Moreactiveduringstressfulsituations
2. Parasympathetic– “restanddigest”• Moreactiveduringquiet,lowstresssituations
Autonomicsystem• Eachpathwayinthissystemusestwoneurons• DendritesandcellbodyofthefirstneuronareintheCNSanditsaxonextendstoaganglionoutsidetheCNS• Aganglion=enlargementofthenervewherethecellbodiesoftheneuronsarelocated• Axonofthesecondneuronextendsfromthegangliontotheeffector(response)
Autonomicsystem
Organizedintosympatheticandparasympatheticvisions:
1. Sympathetic– stressfulsituationsthatinvolvestressorexcitement• Increaseheartbeatrate,raisebloodpressure,dilateairpassageinlungs,inducesweatingandopenpupils
2. Parasympathetic – quiet,lowstresssituations
Autonomicsystem
Organ Sympathetic Parasympatheticheart Increaseheartrate Decreaseheartrate
digestive Decreaseperistalsis Increasesperistalsisliver Increases thereleaseof
glucoseStoresglucose
eyes Dilatespupils Constrictspupilsbladder Relaxessphincter Contractssphincterskin Increasesbloodflow Decreases bloodflow
adrenalgland Causesreleaseofepinephrine
no effect
Homework
• Textbook:pg.434Q.1,3,6;pg.437Q.1,2
• Handoutquestions
• NoFridayorMondayquiz
•UnitTest:NextWednesday(8th)
• Tomorrow:workperiodinthecomputerlab(unittask)
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