2008-SCBI 122 Nervous system

SCBI 122SCBI 122Nervous SystemNervous System

ออ.. ดรดร.. ระพีระพี บุญเปลือง้บุญเปลือง้B 414B 414 ตึกชีววทิยาตึกชีววทิยา

โทรโทร 00--22012201--54825482,, email: email: [email protected]@mahidol.ac.th มกราคมมกราคม ๒๕๕๒๒๕๕๒

TextbooksTextbooks

Campbell, N.A. and Reece, J.B., 2005. Biology. Campbell, N.A. and Reece, J.B., 2005. Biology. 7th edition. Pearson Education Inc. 7th edition. Pearson Education Inc.

Further readings:Further readings:Biology textbooksBiology textbooksInternetInternet

OutlineOutline

Nervous systemNervous systemNeuronNeuronSupporting cellsSupporting cells

Membrane potentialMembrane potentialAction potentialAction potentialThe Central Nervous SystemThe Central Nervous System

The brainThe brainThe spinal cordThe spinal cord

The Peripheral Nervous SystemThe Peripheral Nervous System

Nervous system : 3 overlapping functionsNervous system : 3 overlapping functions

(Campbell, 2008)

Information is communicatedvia a network of neurons,electrically and chemically.

1/27

Nervous systemNervous system

Neurons (or nerve cells or neurones)Neurons (or nerve cells or neurones)Excitability.Excitability.Conductivity.Conductivity.

Supporting cells (or glia or neuroglia)Supporting cells (or glia or neuroglia)Play supporting role w/o participating in Play supporting role w/o participating in nerve signaling.nerve signaling.Outnumber neuron 10Outnumber neuron 10--50 folds.50 folds.

Neuron (nerve cell)Neuron (nerve cell)

Campbell, 2008

Axons vs. DendritesAxons vs. Dendrites Basic Neuron Types (by shape)Basic Neuron Types (by shape)

http://health.howstuffworks.com/brain1.htm

Unipolar

Bipolar Multipolar

2/27

Types of neuron (by function)Types of neuron (by function)

http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/N/Neurons.html

Afferent neuronAssociation neuronEfferent neuron

Three classes of neuronsThree classes of neuronsAfferent neurons: in Afferent neurons: in PNS, sensory receptor PNS, sensory receptor on one end, cell body on one end, cell body near spinal cord, w/o near spinal cord, w/o dendrite and dendrite and presynaptic inputspresynaptic inputsEfferent neurons: in Efferent neurons: in PNS, cell body in CNS, PNS, cell body in CNS, relay inputs to effectorsrelay inputs to effectorsInterneurons: 99% of Interneurons: 99% of neurons, found only in neurons, found only in CNS = 100 billion CNS = 100 billion interneurons, connect interneurons, connect afferentafferent--efferent, efferent, interconnections w/ interconnections w/ interneurons > mindinterneurons > mind

Figure 5-2

Supporting cells vs. NeuronsSupporting cells vs. Neurons

Neurons have two "processes" called axons and dendrites, glial cells have only one. Neurons can generate action potentials, glial cells cannot. Neurons have synapses that use neurotransmitters, glial cells do not have chemical synapses. There are many more glial cells in the brain compared to the number of neurons, (10-50 times more).

Supporting cells (glia, the Supporting cells (glia, the ““glueglue””))

PNSPNSSchwann cells: provide myelin for Schwann cells: provide myelin for individualindividual neurons. neurons. Tubular/cylindrical in shape.Tubular/cylindrical in shape.

CNSCNSOligodendrocytes: provide myelin for Oligodendrocytes: provide myelin for multiplemultiple neurons. neurons. Microglia: the resident Microglia: the resident inin--house immune systemhouse immune system of the of the brain and spinal cord.brain and spinal cord.Astrocytes: the housekeepers, nursemaids, and Astrocytes: the housekeepers, nursemaids, and handservantshandservants of the neurons: maintain the extracellular of the neurons: maintain the extracellular environment, clear away debris, store glucose, etc.environment, clear away debris, store glucose, etc.Ependymal cells: Ependymal cells: line the internal cavities of CNSline the internal cavities of CNS

3/27

GlialGlial cellscells

Campbell, 2008

Schwann cellSchwann cell

Campbell, 2008

Schwann cells: provide myelin for Schwann cells: provide myelin for individualindividual neurons. neurons. Tubular/cylindrical in shape.Tubular/cylindrical in shape.

OligodendrocytesOligodendrocytes

http://homepage.psy.utexas.edu/homepage/class/Psy332/Salinas/Cells/oligo.gif

Form insulating Form insulating myelin sheaths myelin sheaths around the axon around the axon of many neurons.of many neurons.Membranes are Membranes are mostly lipid > mostly lipid > poor conductor poor conductor of electrical of electrical currents.currents.Just like Just like insulation insulation covering covering electrical cords.electrical cords.

The resident The resident inin--house immune systemhouse immune system (macrophage) of (macrophage) of the brain and spinal cord: the brain and spinal cord: phagocytosisphagocytosis: very small.: very small.

MicrogliaMicroglia

http://www.prit.go.jp/Ja/Pgeriat/microgl.htm

Derived from mesoderm

4/27

AstrocyteAstrocyte

http://www.biology.uiowa.edu/daileylab/images/astro1.jpg

Astrocytes: provide structural and metabolic support Astrocytes: provide structural and metabolic support for neurons, communicate w/ one another chemically.for neurons, communicate w/ one another chemically.

Ependymal cellsEpendymal cellsCentral cavity of neural tube Central cavity of neural tube becomes the ventricles of the becomes the ventricles of the brain and the central canal of brain and the central canal of the spinal cordthe spinal cordLine the internal cavities of Line the internal cavities of CNSCNSInvolved in the production of Involved in the production of CSFCSFTheir cilia help circulate CSFTheir cilia help circulate CSFMight serve as neuronal stem Might serve as neuronal stem cells w/ the right cocktailcells w/ the right cocktail

http://ww

w.technion.ac.il/~

mdcourse/274203/slides/N

erve/14http://w

ww

.technion.ac.il/~m

dcourse/274203/slides/Nerve/14 -- E

pendyma%

20E

pendyma%

20 -- %20Central%

20Canal.jpg%

20Central%20Canal.jpg Figure 5-5

Schwann cellSchwann cell

http://academic.kellogg.cc.mi.us/herbrandsonc/bio201_McKinley/f14-6_cellular_organiza_c.jpg

Brain tumorBrain tumorNeuron > no ability of cell Neuron > no ability of cell divisiondivisionGliomasGliomas : brain tumor of : brain tumor of neural origin > glial cellsneural origin > glial cellsBrain tumor of nonBrain tumor of non--neural neural originorigin

Metastasis (spread) Metastasis (spread) MeningiomasMeningiomas: originates from : originates from the the meningismeningis

http://cancer.better-health-home.com/images/brain.jpg

5/27

Nature of nerve signalsEnd of 18th century: Galvani discovered that frog muscles produce electricity19th Century: von Helmholtz and Raymond Dubois found that electrical signals travel along nerves and communicate between neurons and muscles20th Century: mechanisms of nerve transmission explained by the presence of a small number of specialized proteins, neurotransmitter receptors and ionic channelsEvery cell exhibits a membrane potential: difference in electric charges across plasma membrane

http://bioweb.usc.edu/courses/2004-spring/documents/bisc221-baudry_lecture29.pdf

Membrane potentialMembrane potential

Every cell has a Every cell has a voltage, or voltage, or membrane membrane potential, across its potential, across its plasma membrane.plasma membrane.--50 to 50 to --100 mV in 100 mV in animal cells.animal cells.Membrane Membrane potenialpotenialof an of an unstimulatedunstimulatedneuron is neuron is --70 mV70 mV““Resting potentialResting potential””

Campbell & Reece, 2005

Maintenance of a membrane potentialMaintenance of a membrane potential

Selective permeability of the plasma membrane and Selective permeability of the plasma membrane and the Nathe Na++/K/K++ pump maintain the membrane potential.pump maintain the membrane potential.

Campbell, 2005

http://www.lifesci.ucsb.edu/~mcdougal/neurobehavior/modules_homework/lect2.dcr

A-: proteins, a.a., sulfate, phosphate, -ve charged molecules.

Maintenance of a membrane potentialMaintenance of a membrane potential

Selective permeability of the plasma membrane and Selective permeability of the plasma membrane and the Nathe Na++/K/K++ pump maintain the membrane potential.pump maintain the membrane potential.

Campbell, 2005 & 2008

http://www.lifesci.ucsb.edu/~mcdougal/neurobehavior/modules_homework/lect2.dcr

A-: proteins, a.a., sulfate, phosphate, -ve charged molecules.

6/27

Neurons & muscles are excitableOnly neurons and muscles are excitable cells.Membrane potential of an excitable cells in a resting state “Resting membrane potential” = -70 mV, based on ungatedion channels (Na+ and K+) plus Na+/K+ pumpExcitable cells have gated ion channels:

Chemically-gated ion channels: open/close in response to a chemical stimulus.Voltage-gated channels: respond to a change in membrane potential.

Changes in membrane potential result in impulse.Graded vs. resting membrane potentials: hyperpolarization, depolarization and action potential.


VoltageVoltage--gatedgated channelschannels

Open or close in response to changes in membrane potentialOpen or close in response to changes in membrane potential

ChemicallyChemically--gatedgated channelschannels

Conformational changes due to the binding of ligand and Conformational changes due to the binding of ligand and membrane receptorsmembrane receptors

MechanicallyMechanically--gatedgated channelschannels

Respond to stretching or other mechanical Respond to stretching or other mechanical deformationdeformation

7/27

Membrane potentialMembrane potential

Campbell, 2008

HyperpolarizationHyperpolarization

Campbell, 2008

An increase in the voltage An increase in the voltage across the membrane.across the membrane.Opening of KOpening of K++ channel.channel.Increasing of KIncreasing of K++ outflow.outflow.More negative inside.More negative inside.

DepolarizationDepolarization

Campbell, 2008

A decrease in the voltage A decrease in the voltage across the membrane.across the membrane.Opening of NaOpening of Na++ channel.channel.Increasing of NaIncreasing of Na++ inflow.inflow.More positive inside.More positive inside.

Action potentialAction potential

Campbell, 2008

A big change in the voltage A big change in the voltage across the membrane.across the membrane.Opening of more NaOpening of more Na++

channels.channels.Large increasing of NaLarge increasing of Na++ inflow.inflow.More positive inside.More positive inside. 8/27

Action potentialAction potential

Campbell, 2008

Action potentialAction potentialNaNa++ gate channels gate channels are closed. are closed. NaNa++ inactivation inactivation loops are openloops are openKK++ channels are channels are closed.closed.

Resting membrane Resting membrane potential is maintained.potential is maintained.Triggering an action Triggering an action potential.potential.

Campbell, 2008

Action potentialAction potentialA stimulus opens some A stimulus opens some NaNa++ channels.channels.Inactivation loops Inactivation loops remain open.remain open.

If the depolarization If the depolarization reaches threshold reaches threshold ((--50 to 50 to --55 mV), more Na+ 55 mV), more Na+ gates open.gates open.Triggering an action Triggering an action potential.potential.

Campbell, 2008

Action potentialAction potentialNaNa++ channels are open.channels are open.KK++ channels remain channels remain closed.closed.NaNa++ rushes inside.rushes inside.

The inside of the cell The inside of the cell becomes more positive.becomes more positive.

Campbell, 2008 9/27

Action potentialAction potentialNaNa++ channels are channels are closed.closed.KK++ channels are now channels are now open.open.KK++ leaves the cell.leaves the cell.

The inside of the cell loses The inside of the cell loses positive charge.positive charge.The inside of the cell The inside of the cell becomes more negative.becomes more negative.

Campbell, 2008

Action potentialAction potentialNaNa++ channels are closed.channels are closed.KK++ channels remain channels remain open.open.Too much KToo much K++ leaves the leaves the cell.cell.

Then K+ channels are Then K+ channels are closed, returning to the closed, returning to the resting state.resting state.

Campbell, 2008

Refractory period

All-or-none lawMagnitude of the action potential is independent of the strength of the depolarizing stimulus that triggered it, as long as the depolarization reaches the threshold potential.Once the action potential is triggered, the membrane potential goes through a stereotypical sequence of changes.If a stimulus is intense, the neuron will fire repeatedly ( greater frequency of action potentials.)


Action potential propagationAction potential propagation

Campbell, 2008

Action potential Action potential does notdoes nottravel along the axon.travel along the axon.It is repeatedly regenerated It is repeatedly regenerated along the axon.along the axon.Initial depolarization triggers Initial depolarization triggers depolarization of adjacent depolarization of adjacent segments of axon; extensive segments of axon; extensive NaNa++ influx depolarize the next influx depolarize the next segment.segment.Signal moves unidirectionally Signal moves unidirectionally because of the refractory because of the refractory period.period. 10/27


Campbell, 2008


Initial Initial depolarization depolarization triggers triggers depolarization of depolarization of adjacent segments adjacent segments of axon; extensive of axon; extensive NaNa++ influx influx depolarize the depolarize the next segment.next segment.

Campbell, 2008


Signal moves Signal moves unidirectionally unidirectionally because of the because of the refractory refractory period.period.

Campbell, 2008


Several factors affect the speed of the action potential propagations along an axon.

Diameter of the axon: the larger the axon’s diameter, the faster the speed the transmission (resistance to the flow of electricity current is inversely proportional the diameter of the conductor).In vertebrates, many axons are myelinated by oligodendrocytes or Schwann cells. The voltage-gated channels are dense in the nodes of Ranvier. Plus extracellular fluid contacts the axon at the nodes. Na+ current generated by the action potential travels to the next nod to stimulate depolarization/action potential.

11/27

Mye

linat

ed fi

ber

Mye

linat

ed fi

ber

Figure 4-15

Saltatory conductionSaltatory conduction

In vertebrates, many axons are myelinated by oligodendrocytes or Schwann cells. The voltage-gated channels are dense in the nodes of Ranvier. Plus extracellular fluid contacts the axon at the nodes. Na+ current generated by the action potential travelsto the next nod to stimulate depolarization/action potential.

Campbell, 2008

Multiple sclerosisMultiple sclerosis

http://www.sfn.org/skins/main/images/brainbriefings/ms_illus.gif

Autoimmune diseaseAutoimmune diseaseBodyBody’’s defense system s defense system mistakenly attacks the mistakenly attacks the myelin sheathmyelin sheathHerpes (HHVHerpes (HHV--6) viral 6) viral infection infection Virus shares common Virus shares common structural features with structural features with myelin sheathmyelin sheath1 in 1000 people in the US1 in 1000 people in the US

Multiple sclerosisMultiple sclerosis

http://www.hmiworld.org/hmi/issues/July_aug_2005/images/around_ms.jpg

Slows transmission of Slows transmission of impulses in the affected impulses in the affected neuronsneuronsScars interfere with and Scars interfere with and block the propagation of block the propagation of action potentialaction potentialCommon symptomsCommon symptoms

Visual problemsVisual problemsTingling and numbnessTingling and numbnessMuscle weaknessMuscle weaknessImpaired coordinationImpaired coordinationGradual paralysisGradual paralysis 12/27

Synapse are unique cell junctions that control communication between:

Neuron and neuronSensory receptors and sensory neuronsMotor neurons and muscle cellsNeurons and gland cells

Two types of synapses:Electrical synapseChemical synapse

Communication at synapseCommunication at synapseSynapsesSynapses

A nerve cell in the brain may have about 10, 000 to 150, 000 synapses.

SynapsesSynapses

Campbell, 2008

Electrical synapseElectrical synapse

Connections by gap junction.Directly from pre- to postsynaptic cellNo delayNo loss of strengthIn fish, lobsters and other crustaceans.

http

://w

ww

.ncb

i.nlm

.nih

.gov

/boo

ks/b

v.fc

gi?r

id=

neur

osci

.figg

rp.3

19

13/27

Chemical synapseChemical synapse

Separated by a synaptic cleft.Electrical signal gets converted to chemical one which travels across the cleft Then gets converted back to electrical signal.

http

://b

io.w

inon

a.msu

s.edu

/ber

g/30

8s04

/Lec

-not

e/9-

new

.htm

Campbell, 2008

Chemical synapseChemical synapse

http

://w

ww

.ncb

i.nlm

.nih

.gov

/boo

ks/b

v.fc

gi?r

id=

neur

osci

.figg

rp.3

22

Chem

ical s

ynap

seCh

emica

l syn

apse

http

://w

ww

.ncb

i.nlm

.nih

.gov

/boo

ks/b

v.fc

gi?r

id=

neur

osci

.figg

rp.3

86

Life cycle of neurotransmittersLife cycle of neurotransmitters

14/27

NeurotransmittersNeurotransmitters

http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=neurosci.section.375

An experiment of Otto Loewi, a German physiologist, in 1926.

Acetylcholine

NeurotransmittersNeurotransmittersChemical signals released from presynaptic nerve Chemical signals released from presynaptic nerve terminals into the synaptic cleft. terminals into the synaptic cleft. The subsequent binding of neurotransmitters to The subsequent binding of neurotransmitters to specific receptors on postsynaptic neurons (or other specific receptors on postsynaptic neurons (or other classes of target cells) transiently changes the classes of target cells) transiently changes the electrical properties of the target cells.electrical properties of the target cells.Leading to an enormous variety of postsynaptic Leading to an enormous variety of postsynaptic effects .effects .



Two majors categories of neurotransmitters, based Two majors categories of neurotransmitters, based on their sizes:on their sizes:

SmallSmall--molecule neurotransmitters: smallmolecule neurotransmitters: smallNeuropeptidesNeuropeptides: large, 3: large, 3--36 amino acids.36 amino acids.


Campbell & Reece, 2005 15/27

AcetylcholineAcetylcholine


One of the most common neurotransmitters in both One of the most common neurotransmitters in both vertebrates and invertebrates.vertebrates and invertebrates.In vertebrate CNS, In vertebrate CNS, AChACh can be inhibitory or can be inhibitory or excitatory:excitatory:

Excitatory to vertebrate skeletal muscles > Excitatory to vertebrate skeletal muscles > contraction of skeletal muscles.contraction of skeletal muscles.Inhibitory to cardiac muscle cells > reduce the Inhibitory to cardiac muscle cells > reduce the strength and rate of cardiac muscle cell strength and rate of cardiac muscle cell contraction.contraction.

Communication at synapseCommunication at synapse


Excitatory Excitatory synapsesynapseEPSP EPSP excitatory excitatory postsynaptic postsynaptic potentialpotentialInhibitory Inhibitory synapsesynapseIPSP IPSP inhibitory inhibitory postsynaptic postsynaptic potentialpotential

Summation of postsynaptic potentialsSummation of postsynaptic potentials

Campbell, 2008

Types of nerve circuitTypes of nerve circuit

Poolsa-nguan, 2001

16/27

Simple reflex arcSimple reflex arc

Campbell, 2008

Simple reflex arcSimple reflex arc

http://academic.kellogg.cc.mi.us/herbrandsonc/bio201_McKinley/f16-13_monosynaptic_and_c.jpg

Crossed extensor reflex

Pathways that cross over to the opposite side of the spinal cord to stimulate the knee extensor and inhibit its flexor

To be learned

17/27

Diversity of nervous systemsDiversity of nervous systems


Development of the brainDevelopment of the brain


Vertebrate nervous systemVertebrate nervous system

Campbell, 2008

CNS CNS Brain and Spinal cord, develop Brain and Spinal cord, develop from the neural tube.from the neural tube.Cerebrospinal fluid (CSF) fills Cerebrospinal fluid (CSF) fills brain brain ventricalventrical & central canal & central canal in in spincalspincal cord, delivering cord, delivering neutreintsneutreints, hormones and , hormones and wbcwbc..The brain is surrounded by The brain is surrounded by meninges.meninges.Axons are wrapped with Axons are wrapped with myleinmylein sheaths, appearing sheaths, appearing white > white > whitewhite matter.matter.Gray matter > dendrites + cell Gray matter > dendrites + cell bodiesbodies

MeningesMeninges

http

://a

cade

mic

.kel

logg

.cc.m

i.us/

herb

rand

sonc

/bio

201_

McK

inley

/f15

-4_c

rani

al_m

enin

ges_

c.jpg

Dura mater: thick, durable membrane, closest to the Dura mater: thick, durable membrane, closest to the skullskullArachnoidArachnoid mater: mater: spider webspider web--like appearance, provides a cushioning effect for like appearance, provides a cushioning effect for the CNS the CNS PiaPia mater: very delicate membrane, attached to the mater: very delicate membrane, attached to the brainbrain or the or the spinal cordspinal cord, , Within the Within the piapia mater are mater are capillariescapillaries responsible for nourishing the brain. responsible for nourishing the brain.

18/27

MeningesMeninges

http://academic.kellogg.cc.mi.us/herbrandsonc/bio201_McKinley/f16-2b_spinal_meninges__c.jpg http://trc.ucdavis.edu/biosci10v/bis10v/week10/cerebrospinal.gif

The brainThe brain

Lateralization of brain functions; Right and left hemispheres do not perform the same function:

Left hemisphere: language, math logic operations, processing of serial sequences of informationRight hemisphere: pattern recognition, face recognition, spatial relations, nonverbal ideation, emotional processing

The brainThe brain

http://academic.kellogg.cc.mi.us/herbrandsonc/bio201_McKinley/f15-10l_cerebral_hemisp_c.jpg 19/27

The brainThe brain


CerebrumCerebrum

Campbell, 2005

Cerebral cortexCerebral cortex

Campbell & Reece, 2005Campbell, 2008

ThalamusThalamusMain input center for sensory information Main input center for sensory information going to cerebrum.going to cerebrum.Incoming from all the sense is sorted out here Incoming from all the sense is sorted out here and sent to appropriate part of the brain.and sent to appropriate part of the brain.Also receives input from the cerebrum and Also receives input from the cerebrum and other part of the brain that regulate emotion other part of the brain that regulate emotion and arousal.and arousal.

20/27

HypothalamusHypothalamusOne of the most important brain region in One of the most important brain region in homeostatic regulation.homeostatic regulation.BodyBody’’s thermostat, hunger and thirst centers.s thermostat, hunger and thirst centers.Other basic survival mechanisms: breathing, Other basic survival mechanisms: breathing, blood pressureblood pressureSexual and mating behavior.Sexual and mating behavior.Pleasure.Pleasure.Fight or flight response.Fight or flight response.

MidbrainMidbrainContains centers for the receipt and Contains centers for the receipt and integration of several sensory information.integration of several sensory information.Then sends the sensory information to the Then sends the sensory information to the forebrain.forebrain.Mammals use this part of the brain only for Mammals use this part of the brain only for eye reflexes.eye reflexes.

http

://a

cade

mic

.kel

logg

.cc.m

i.us/

herb

rand

sonc

/bio

201_

McK

inle

y/f1

5-22

a_ce

rebe

llum

_mid

s_c.j

pg

HindbrainHindbrain HindbrainHindbrainMedulla:Medulla:

Centers for visceral functions: breathing, heart Centers for visceral functions: breathing, heart beating, swallowing, vomiting and digestion.beating, swallowing, vomiting and digestion.

Pons:Pons:Centers for breathing regulation.Centers for breathing regulation.

Cerebellum:Cerebellum:Learning and remembering motor responses: Learning and remembering motor responses: providing autonomic coordination of movements providing autonomic coordination of movements and balance.and balance.

21/27

BrainstemBrainstem

http://academic.kellogg.cc.mi.us/herbrandsonc/bio201_McKinley/f15-20a_pons_longitudin_c.jpg

BrainstemBrainstemAlso called the Also called the ““lower brainlower brain””..Three parts of the brain:Three parts of the brain:

Medulla oblongataMedulla oblongataPonsPonsMidbrainMidbrain

Functions in homeostasis, coordination of Functions in homeostasis, coordination of movements, conduction of information to movements, conduction of information to higher brain center.higher brain center.

Spinal cordSpinal cord

http

://t

rc.u

cdav

is.ed

u/bi

osci1

0v/b

is10v

/wee

k10/

spin

alcor

dstru

c.gif


http

://w

ww

.mer

ck.co

m/m

edia/

mm

he2/

figur

es/f

g076

_2_2

.gif

22/27

Spinal cordSpinal cordht

tp:/

/bio

web

.usc

.edu/

cour

ses/

2004

-spr

ing/

docu

men

ts/b

isc22

1-ba

udry

_lec

ture

29.p

df

Main pathway Main pathway connecting the connecting the brain and brain and peripheral peripheral nervous system.nervous system.Several reflex Several reflex reactions.reactions.Central canal.Central canal.Gray matter Gray matter (inside).(inside).White matter White matter (outside).(outside).


http

://b

iow

eb.u

sc.ed

u/co

urse

s/20

04-s

prin

g/do

cum

ents

/bisc

221-

baud

ry_l

ectu

re29

.pdf

http://www.becomehealthynow.com/images/organs/nervous/sp_cord_section.jpg


http://academic.kellogg.cc.mi.us/herbrandsonc/bio201_McKinley/f16-4_neuron_pathways_a_c.jpg

Peripheral nervous systemPeripheral nervous system


Cranial nervesCranial nervesOriginated in the brainOriginated in the brainInnervate organs of head Innervate organs of head and upper bodyand upper body12 pairs in mammals12 pairs in mammals

Spinal nervesSpinal nervesOriginated in spinal cord.Originated in spinal cord.Innervate in the entire Innervate in the entire bodybody31 pairs in mammals.31 pairs in mammals.

Both contain sensory Both contain sensory and motor neurons.and motor neurons.

23/27

Cranial nervesCranial nerves

http

://a

cade

mic

.kel

logg

.cc.m

i.us/

herb

rand

sonc

/bio

201_

McK

inle

y/f1

5-24

l_cr

anial

_ner

ves_

c.jpg

I.I. Olfactory*Olfactory*II.II. Optic*Optic*III.III. OculomotorOculomotorIV.IV. TrochlearTrochlearV.V. TrigeminalTrigeminalVI.VI. AbducensAbducensVII.VII. FacialFacialVIII.VIII. Auditory*Auditory*IX.IX. GlossopharyngealGlossopharyngealX.X. VagusVagusXI.XI. Spinal accessorySpinal accessoryXII.XII. HypoglossalHypoglossal

Cranial nervesCranial nerves

http

://w

ww

1.ap

psta

te.ed

u/~

clar

khm

/sw

allow

_dist

ance

/im

ages

/cra

nial%

20ne

rves

.jpg

I.I. Olfactory*Olfactory*II.II. Optic*Optic*III.III. OculomotorOculomotorIV.IV. TrochlearTrochlearV.V. TrigeminalTrigeminalVI.VI. AbducensAbducensVII.VII. FacialFacialVIII.VIII. Auditory*Auditory*IX.IX. GlossopharyngealGlossopharyngealX.X. VagusVagusXI.XI. Spinal accessorySpinal accessoryXII.XII. HypoglossalHypoglossal

Spinal nervesSpinal nerves31 pairs:31 pairs:

8 cervical8 cervical12 thoracic12 thoracic5 lumbar5 lumbar5 sacral5 sacral1 1 coccygealcoccygeal

http://academic.kellogg.cc.mi.us/herbrandsonc/bio201_McKinley/f16-1a_gross_anatomy_of_c.jpg

Peripheral nervous systemPeripheral nervous system

Campbell & Reece, 2005 24/27

http://academic.kellogg.cc.mi.us/herbrandsonc/bio201_McKinley/f14-2_functional_organi_c.jpg

Peripheral nervous systemPeripheral nervous system Autonomous nervous systemAutonomous nervous system

http://academic.kellogg.cc.mi.us/herbrandsonc/bio201_McKinley/f18-2_components_of_the_c.jpg

SymSym--parasympathetic nervesparasympathetic nerves


Act on body Act on body organs with organs with opposing opposing effects.effects.

http

://a

cade

mic

.kel

logg

.cc.m

i.us/

herb

rand

sonc

/bio

201_

McK

inle

y/f1

8-5_

over

view

_of_

para

s_c.j

pg

Para

sym

path

etic

divi

sion

Para

sym

path

etic

divi

sion

25/27

http

://a

cade

mic

.kel

logg

.cc.m

i.us/

herb

rand

sonc

/bio

201_

McK

inle

y/f1

8-6_

over

view

_of_

sym

pa_c

.jpg

Sym

path

etic

div

ision

Sym

path

etic

div

ision

SymSym--parasympathetic nervesparasympathetic nerves

http://academic.kellogg.cc.mi.us/herbrandsonc/bio201_McKinley/table18-2_comparison_of.jpg

http

://a

cade

mic

.kel

logg

.cc.m

i.us/

herb

rand

sonc

/bio

201_

McK

inley

/f18

-4_a

nato

mic_

diffe

ren_

c.jpg

Acetylcholine

AcetylcholineNorepinephrine

Acetylcholine

26/27

Arousal and energy generation in response to Arousal and energy generation in response to stress:stress:

The heart beats faster.The heart beats faster.The liver converts glycogen to glucose.The liver converts glycogen to glucose.Bronchi of the lungs dilate and support increased Bronchi of the lungs dilate and support increased gas exchanged.gas exchanged.Digestion is inhibited.Digestion is inhibited.Secretion of adrenaline from adrenal medulla is Secretion of adrenaline from adrenal medulla is stimulated.stimulated.

Sympathetic nervesSympathetic nerves


Calming and returning to selfCalming and returning to self--maintenance maintenance functions:functions:

Decreases heart rate.Decreases heart rate.Constriction of bronchi in lungs.Constriction of bronchi in lungs.Stimulate digestion.Stimulate digestion.

Parasympathetic nervesParasympathetic nerves


27/27

Documents

2008-SCBI 122 Nervous system