organization and function of the nervous system

8/9/2019 Organization and Function of the Nervous System

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Enrico C. AguilaNovember 23, 2009


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P age 2

1. Define key terminologyin the study of nervoussystem anatomy.

2. Outline the organization

of structures in thenervous system.

3. List the differentstructures of the nervous

system


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Page

Front Ant e rior Rostr a l

Sid eLa te r a l

Ba ckP ost e rior Ca ud a l

TopSup e rior Dors a l

BottomInf e rior Ve ntr a l

Me dia l


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P age 5


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Cerebralhemispheres

Diencephalon Cerebellum Midbrain

Pons Medulla Spinal Cord


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P age 8

M eninges Pia mater Arachnoid mater Dura mater

S uspended in cerebrospinal fluidBones of the skull andvertebral column


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P age 9


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Br a inBr a in

For e br a in(P ros e nc e ph a lon)

For e br a in(P ros e nc e ph a lon)

Ce r e brumCe r e brum

Limbic Syst e mLimbic Syst e m

Tha la musTha la mus

Hypoth a la musHypoth a la mus

i br a in( ie nc e ph a lon)

i br a in( ie nc e ph a lon)

Re ticula r form a tionRe ticula r form a tion

Hin br a in(Rhomb e nc e ph a lon)

Hin br a in(Rhomb e nc e ph a lon)

Ce r e be llumCe r e be llum

P onsP ons

ed ullaMed ulla


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P age


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P age 2

Largest part of the brain2 cerebral hemispheres, connected by a mass of whitematter called the corpus callosum


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Compos e d of gr a y m a tte r (n e rve ce ll bodi e s)Compos e d of gr a y m a tte r (n e rve ce ll bodi e s)

Cort ex

Gyri ( gyrus) folds

Fissur e s th a t s e pa r a te the gyri from ea ch oth e r Fissur e s th a t s e pa r a te the gyri from ea ch oth e r

Sulci (sulcus)

Subdivisions of a ce r e br a l he misph e r e form e d by groups of gyriSubdivisions of a ce r e br a l he misph e r e form e d by groups of gyri

Lob e s


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Ce ntr a l cor e of whit e ma tte r cont a ining la r ge ma ss e s of gr a y m a tte r Ce ntr a l cor e of whit e ma tte r cont a ining la r ge ma ss e s of gr a y m a tte r

Ba s a l ga ng lia

Fa n sh a pe d coll e ction of n e rve fibe rsPa ss e s in th e white ma tte r to a nd from th e ce r e br a l cort ex a nd th e br a inst e mFa n sh a pe d coll e ction of n e rve fibe rsPa ss e s in th e white ma tte r to a nd from th e ce r e br a l cort ex a nd th e br a inst e m

Coron a r a dia ta

Conve r ge nc e of th e coron a r a dia ta in th e ba s a l ga ng liaConve r ge nc e of th e coron a r a dia ta in th e ba s a l ga ng lia

Inte rna l c a psul e

Ta ile d nucl e us on th e me dia l sid e of th e inte rna l ca psul eTa ile d nucl e us on th e me dia l sid e of th e inte rna l ca psul e

Ca ud a te nucl e us

Le ns sh a pe d nucl e us on th e la te r a l sid e of th e inte rna l c a psul eLe ns sh a pe d nucl e us on th e la te r a l sid e of th e inte rna l c a psul e

Le ntiform nucl e us

La te r a l ve ntricl e sThird ve ntricl eFourth v e ntricl e

La te r a l ve ntricl e sThird ve ntricl eFourth v e ntricl e

Ve ntricl e s


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Thalamus

Large egg-shaped massof gray matter that lieson either side of thethird ventricle

Large egg-shaped massof gray matter that lieson either side of thethird ventricle

Hypothalamus

Forms the lower part of the lateral wall and floor of the third ventricle

Forms the lower part of the lateral wall and floor of the third ventricle


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P age

N arrow part of the brain that connects the forebrain to thehindbraincomprises the tectum(or corpora quadrigemini),tegmentum, the ventricular mesocoelia (or "iter"), and the

cerebral peduncles, as well as several nuclei and fasciculi


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P age

Brainstem M edulla oblongata PonsC erebellum


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P age 8

C onical in shapeC onnects the pons to thespinal cordC ontains nuclei

S erves as conduit forascending and descendingfibers of the CNS


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P age 9

Located on the anteriorsurface of the cerebellum,inferior to the midbrainand superior to the

medullaC ontains a large number of transverse nerve fibersconnecting the 2 cerebellar

hemispheresAlso contains nuclei andascending and descendingfibers


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P age 20

Lies within the posteriorcranial fossa, posterior tothe pons and the medulla2 hemispheres connected by

a middle portion called thevermisC erebellar Peduncles: S uperior midbrain

M iddle pons Inferior - medulla


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P age 2

C erebellar cortex graymatterDentate nucleus gray

matter embedded in thewhite matter of thecerebellum


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P age 22

C ontinuous with themedulla31 segments give rise to 31

pairs of spinal nerve roots


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P age 23


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N ervous S ystemN ervous S ystem

SensorySensory(Afferent)(Afferent)DivisionDivision

P N S to C N SP N S to C N SContain receptorsContain receptors

Somatic SensorySomatic Sensory Visceral SensoryVisceral Sensory

Motor (Efferent)Motor (Efferent)DivisionDivision

C N S to the rest of bodyC N S to the rest of bodySends motor informationSends motor information

to effectorsto effectors

Somatic Motor Somatic Motor Autonomic Motor Autonomic Motor


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C oordinates all body functions, enabling a person toadapt to changes in internal and external environmentTransmits information throughout the body thruelectrical impulses

S tores, processes, retrieves informationReceives sensory inputS ends information for motor outputProtects the body through reflexes, maintaining body

homeostasisC omplex brain functions: memory, emotions, languageand speech, sleep and wakefulness, motor control


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C entral nervous system

sensoryinformation

withinafferentdivision

motor commands

withinefferentdivision

S omaticnervoussystem

Autonomicnervous system

parasympatheticdivision

sympatheticdivision

Peripheralnervous systemincludes

special sensoryreceptors somaticsensory receptors

visceral sensory receptors

Information processing

-smoothmuscle-cardiacmuscle-glands

skeletalmuscle


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N eurons

Cells that transmitinformation

All polarizedCan be classifiedaccording to the number of polesMay look different but

have common feature

Glial Cells

N eurogliaSupporting cells of the

nervous systemSurround neurons andhold them in placeSupply nutrients andoxygen to neurons

Insulate one neuron fromanother Destroy and remove thecarcasses of dead neurons


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Ne urons

Bipola r P s e udounipol a r Multipola r

Glia l Ce lls

Astrocyt e sOligod e ndrocyt e sMicrog liaSchw a nn C e lls


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P age 32


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P age 33

M ost basic unit of the nervous systemEnclosed in a single semi-permeable membrane calledplasmalemma

B asic st r uctu r e of a r ep r esentati v e neu r ondendrites cell body

(soma)a xon

synaptic terminals


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C ell bodyPerikaryon - N ucleus

N erve cell bodies in the C N SN erve cell bodies in the C N S

N ucleus

N erve cell bodies in the P N SN erve cell bodies in the P N S

Ganglia

Laminated sheets of nerve cell bodies on the surface of cerebrumand cerebellumLaminated sheets of nerve cell bodies on the surface of cerebrumand cerebellum

Cerebral and cerebellar cortex

Aggregations of nerve cell bodies in the brain and spinal cordAggregations of nerve cell bodies in the brain and spinal cord

Gray matter


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Axon

Single fiber extending toother parts of the nervoussystem (muscle/gland)Conducts impulses awayfrom the nerve cell bodyOne axon and may splitinto numerous terminal

branches as it nears thetarget structure.Responsible for efferent

processes

Single fiber extending toother parts of the nervoussystem (muscle/gland)Conducts impulses awayfrom the nerve cell bodyOne axon and may splitinto numerous terminal

branches as it nears thetarget structure.Responsible for efferent

processes

Dendrite

Branching processes thatreceive stimuli andconduct impulsesgenerated toward thenerve cell bodyResponsible for afferent

processes

Branching processes thatreceive stimuli andconduct impulsesgenerated toward thenerve cell bodyResponsible for afferent

processes


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Axon hillock - int eg r a te sIncomin g signa ls


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P age 3

a bundle of nerve fibers having a common origin, function and termination

TractTract

a small, anatomically distinct bundle of nerve fibers

FasciculusFasciculus

a bundle of fibers resembling an arm-like process or structure

BrachiumBrachium

a stem-like collection of nerve fibers connecting different areas in the C N S

PedunclePeduncle

pillar-like collection of nerve fibersColumnColumn

a ribbon or band of fibers

LemniscusLemniscus


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P age 38

Microscopic cord-like structure comprising a collection of nerve fibers that conveyimpulses between a part of the C N S and a region of the body

N erve N erve

N etwork or tangle of nerves

N erve plexus N erve plexus

Portion of a nerve by which it arises from the spinal cord

N erve root N erve root

N erve trunk N erve trunk

N erve cord N erve cord

Branch of nerves (a branch of connecting two nerves)

RamusRamus


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Lateral Cord

Medial Cord

Posterior Cord


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P age 0

Covers the central andperipheral nerve fibers

Myelin sheathMyelin sheath

Sheath formed by theSchwann cells outsidethe myelin sheath of the peripheral nerves.

NeurolemmaNeurolemma

Myelinated nerve fibersin the brain and spinalcord

White matter White matter


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P age

Bipolar Pseudounipolar Multipolar

StructureStructure

InterneuronsAfferent neuronsEfferent neurons

FunctionFunction

Golgi Type IGolgi Type II

SizeSize


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P age 2

Has two processes; one a xon,one dendrite

Bipolar Bipolar

Appear to have only oneprocess that bifurcatesHas a peripheral process anda central process that functionlike a xons

P seudounipolar P seudounipolar

Has numerous processes;usually one a xon and anumber of dendrites.

Multipolar Multipolar


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P age 3


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Sensory functionPropagate APs from sensory receptors basedon touch (pressure/stretch), taste, odor, sound,vision towardthe C N SSynapse with interneurons

Afferent N eurons

Association functionReceive and interpret APs from sensoryneuronsSynapse with motor neurons

Interneurons

Motor functionPropagate APs away from the C N SSynapse with effectors

Efferent N eurons


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P age 5

Cell bodyFor the Trunk and Extremities: Dorsal root ganglionFor the Face: Ganglia adjacent to Brainstem or nuclei within Brainstem

Afferent N euronsAfferent N eurons

Deeply imbedded within spinal cord and other C N S structuresForm connections between motor neurons, sensory neurons, and inputcoming down to the spinal cord from higher brain centersComprise 99.9% of the nervous system

InterneuronsInterneurons

Cell bodyFor the Trunk and Extremities: Spinal CordFor the Face: N uclei within Brainstem

Efferent N euronsEfferent N eurons


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P age

Golgi Type ILong axon that may reach upto one meter

in lengthForm the long fiber tracts in the brain andspinal cord

Golgi Type II

Short axons that end in the vicinity of the body

SizeSize


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P age

Astrocytes Astrocytes O ligodend r ocytesO ligodend r ocytes

Mic r ogliaMic r oglia Ependymal cellsEpendymal cells

Satellite cellsSatellite cells Schwann CellsSchwann Cells


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P age 8

ast r ocytesLa r gest and most nume r ous glial cells

---maintain blood-brainbarrier

---p rovide structural support

---absorb and recycleneurotransmitters

---from scar tissue after injury


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P age 9

oligodend r ocytesha v e smalle r cell bodies and fewe r

pr ocesses

---myelinate CNS a xons

myelin (multilayered membrane sheath)

nodes (nodes of Ranvier)inte r nodes

---provide structural framework


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P age 50

mic r ogliaaccounts fo r 5% of the C NS glial cells; the

p r ocesses ha v e many fine b r anches

---remove cells debris,wastes, and pathogens


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P age 5

Ependymal cellsVent r icles of the b r ain and cent r al canal of the S C a r e lined by

ependyma.

C uboidal o r columna r shaped; ha v e slende r p r ocesses

---assist in producing,circulating, andmonitoring of cerebrospinal fluid


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P age 52

Satellite cells

neu r on

Su rr ound the neu r on cell bodies in pe r iphe r alganglia.

---regulate nutrients for neurons andganglia


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Schwann cells

Myelinated axon

Unmyelinated axon

Fo r mation of myelin

---surround all a xons whether its unmyelinated or myelinated

---responsible for myelination of peripheral a xons

organization and function of the nervous system

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