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7/31/2019 Slides SN1

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O Desenvolvimento

do Sistema Nervoso


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Funo

receber informaes sobre as variaes externas e

internas e produzir respostas a essas variaes

atravs dos msculos e glndulas. a memria, que corresponde a capacidade de

armazenar informaes e depois resgat-las, o

aprendizado, o intelecto, o pensamento e a

personalidade.


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Organizao do Sistema NervosoSistema Nervoso

Sistema Nervoso Central Sistema Nervoso Perifrico

Encfalo Medula espinhal Diviso Aferente Diviso Eferente

NeurniosSensitivos

Somticos

NeurniosSensitivos

Viscerais

SistemaNervoso

Autnomo

SistemaNervoso

Somtico

Parte Simptica Parte Parassimptica


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Organizao do Sistema Nervoso


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Estrutura de um neurnio:

Corpo Celular

Ncleos

Centros

Gnglios

Componentes do Sistema Nervoso

Neurnios:

Unidade Morfofuncional do SN

No se multiplicam aps o nascimento, exceto os neurnios do bulbo

olfatrio, cerebelo e epitfalo olfatrio.


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Neurnio


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Pregas neurais

Sulco neuralTubo neural

O Tubo neural Se diferencia em

SNC, que consiste em encfalo e

Medula espinal

A Crista neural d origem s

clulas formadoras da maior parte

do SNP e SNA, constitudos pelos

gnglios cranianos, espinhais e

autnomos.


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Fechamento do

tubo neural em

ambos os sentidos

Neurporo ceflico 25 dia

Neurporo caudal

27 dia

Cristas neurais


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A, Dorsal view of an embryo of

about 23 days,

B, Lateral view of an embryo ofabout 24 days, showing the

forebrain prominence and

closing of the rostralneuropore.

C, Diagrammatic sagittal

section of this embryo, showing

the transitory communicationof the neural canal with theamniotic cavity (arrows).

D, Lateral view of an embryo of

about 27 days. Note that the

neuropores shown in B are

closed.


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Seco diagramtica sagital de embrio mostrando a comunicao

transitria do canal neural com a cavidade amnitica (setas)

A abertura ceflica o neurporo rostral, ou anterior, se fecha em tornodo 25 dia, o neurporo caudal, ou posterior, se fecha dois dias maistarde.


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As paredes do tubo neural se espessam, formando oencfalo e a medula espinhal.

O canal neural do tubo neural converte-se no sistemaventricular do encfalo e no canal central da medulaespinhal.


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Histognese dasClulas do SNC

After further

development the

multipolar neuroblast(lower left) becomes a

nerve cell or neuron.

Neuroepithelial cellsgive rise to all neuronsand macroglial cells.

Microglial cells are

derived frommesenchymal cellsthat invade the

developing nervous

system with the blood

vessels


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Tubo Neural

Extremidade ceflica

Hemisfrios cerebrais

encfalo

Anterior ou prosencfalo Mdio ou mesencfalo Posterior ou rombencfalo

Mesencfalo adulto

(tegumento, teto e

pednculosceflicos

Ponte, cerebelo e medula

(bulbo)

Tele e diencfalo

tlamo e hipotlamo

Meta e mielencfalo


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telencfalo diencfalo mesencfalo metencfalo mieloencfalo


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ENCFALO

VESCULAS ENCEFLICAS PRIMITIVAS

(1)O prosencfaloou encfalo anterior

(2)O mesencfaloou encfalo mdio

(3)O rombencfaloou encfalo posterior


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Diagrammatic sketches of the brain vesicles, indicating the adult derivatives of their walls and

cavities. *The rostral part of the third ventricle forms from the cavity of the telencephalon; most

of this ventricle is derived from the cavity of the diencephalon.

Vesculas pticas

Torna-se cada vez mais delgado

Organizao do sistema nervoso

A partir da 6semana


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Vista lateral das vesculas enceflicase parte alta da medula espinhal de

embrio de quatro semanas


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A, Schematic lateral view of an

embryo of about 28 days, showing

the three primary brain

vesicles: forebrain,midbrain, and hindbrain. Twoflexures demarcate the primary

divisions of the brain. B,

Transverse section of this embryo,

showing the neural tube that will

develop into the spinal cord in thisregion. The spinal ganglia derived

from the neural crest are also

shown. C, Schematic lateral view

of the central nervous system of a

6-week embryo, showing the

secondary brain vesicles and

pontine flexure. The flexure (bend)occurs as the brain grows rapidly.

O dobramento na 4 semana

importante para a modelagem do

sistema nervoso

Flexura cervical

Flexura ceflica


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FLEXURAS ENCEFLICAS

Flexura Cervical:Entre o rombencfalo e a medula espinal

Flexura Ceflica:No mesencfalo

Flexura Pontina: Entre o metencfalo e o mielencflo


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Esquema mostrando a formao das flexurasceflicas, cervical e pontina


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Rombencfalo

Podem ser claramente distinguidas as placas alar ebasal, separadas pelo sulco limitante.

Contm ncleos

motores

Mielencfalo

Colunas de ncleos (agregadosde corpos celulares neuronais noencfalo) viscerais aferentes(indo p/ o encfalo) eeferentes (saindo do encfalo).


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XII- (Hipoglosso)- MotorXI- Acessrio (Motor); X-vago(misto)IX-Glossofarngeo(misto).

A placa do teto do mielencfalo, est constituda por uma nica camada declulas ependimrias, recobertas externamente pela pia-mter(mesnquimavascular). Essas estruturas constituem o plexo coride, produtor do lquido

cefalorraquidiano.


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Colculos superiores

Colculos inferiores

Centros de Reflexosauditivos

Centro deReflexos visuaisOs Colculos formam-se por

intensa proliferao de clulasdo manto que migram para zona

marginal

Os ncleos do III nervo craniano oculomotor- a partir das placasbasais, localizam-se ao nvel dos

colculos superiores

Os ncleos do IV nervo craniano-troclear a partir das placasbasais, localizam-se ao nvel doscolculos inferiores

Mesencfalo


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Vista externa do encfalono fim da quinta semana

Hemisfrios

cerebrais crescem

e cobrem

diencfalo,

mesencfalo e

rombencfalo


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A, Sketch of the developing brain at the end of the

fifth week. C Sagittal sections of the hindbrain at

6 and 17 weeks, respectively, showing successive

stages in the development of the pons andcerebellum.


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Formao da medula espinhal

O tero caudal da placa e do tubo neural representa a futuramedula espinhal.

Diagrama ilustrando o desenvolvimento da medula espinhal


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Formao das Meninges da Medula Espinhal

A dura-mter do mesnquima mesodermaque envolve o tubo neural.

As Leptomeninges pia-mter e a aracnideoriginam-se das clulas das cristas neurais.

Durante a quinta semana, comea a formar-se um

fluido cerebro

espinhal (FCS, lquor), que podeconstituir um meio nutritivo para as clulas epiteliais

dos tecidos neurais.


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Sistema

Nervoso

Perifrico


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Pregas neurais

Sulco neuralTubo neural

O Tubo neural Se diferencia em

SNC, que consiste em encfalo e

Medula espinal

A Crista neural d origem s

clulas formadoras da maior partedo SNP e SNA, constitudos pelos

gnglios cranianos, espinhais e

autnomos.


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Diagrams showing some

derivatives of the neural

crest.

Neural crest cells also

differentiate into the cellsin the afferent ganglia of

cranial nerves and many

other structures The

formation of a spinal

nerve is also illustrated.


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Os nervos cranianos podem ser subdivididos com base em suaf i b i l i


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funo ou em sua origem embriolgica.

motor

Sensitivo

O vago misto,

predominantementemotor


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Anomalias

Congnitas do

Sistema Nervoso


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3 a cada mil nascimentos

Geralmente devido a fatores multifatoriais

Tipos

Estruturais

Distrbios na organizao das clulas

Erros de metabolismo

Diagnosticados por alto nvel de alfa-fetoprotena no lquido

amnitico ou por ultrasson


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Schematic illustrations

explaining the

embryological basis ofNTDs. Meroanencephaly -

partial absence of the

brain - results from

defective closure of the

rostral neuropore, and

meningomyelocele results

from defective closure of

the caudal neuropore.

Defeitos de fechamento

do tubo neural


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female child with a hairy patch in

the lumbosacral region, indicating

the site of a spina bifida occulta

Photographs of infants with spina bifida

cystica. A, Spina bifida with

meningomyelocele in the lumbar region.

B, Spina bifida with myeloschisis in the

lumbar region. Note the nerve

involvement has affected the lower limbs.


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Photograph of the back of a newborn with a large lumbar meningomyelocele. The

neural tube defect (NTD) is covered with a thin membrane. (Courtesy of Dr. AE

Chudley, Section of Genetics and Metabolism, Department of Pediatrics and Child

Health, Children's Hospital and University of Manitoba, Winnipeg, Manitoba,

Canada.).


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Photograph of a 19-week female fetus showing an open

spinal defect in the lumbosacral region (spina bifida with

meningomyelocele). (Courtesy of Dr. Joseph R. Siebert,

Children's Hospital and Regional Medical Center, Seattle,

Washington.).

A, Photograph of a human embryo of about 30 days. The

white arrow indicates the site of the NTD resulting from

failure of closure of the caudal neuropore. Normally this

neuropore is closed by day 28. B, Photomicrograph of a

transverse section through the NTD. The black arrow

indicates an abnormal fold of neural tissue extending over

the left side of the embryo. It appears that this overgrown

neural fold has prevented closure of the neural tube.

Meningoencefalocele


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Schematic drawings illustrating cranium bifidum (bony defect in cranium) and various types of

herniation of the brain and/or meninges. A, Sketch of the head of a newborn infant with a large

protrusion from the occipital region of the cranium. The upper red circle indicates a cranial

defect at the posterior fontanelle. The lower red circle indicates a cranial defect near the

foramen magnum. B, Meningocele consisting of a protrusion of the cranial meninges that is

filled with cerebrospinal fluid (CSF). C, Meningoencephalocele consisting of a protrusion of part

of the cerebellum that is covered by meninges and skin. D, Meningohydroencephalocele

consisting of a protrusion of part of the occipital lobe that contains part of the posterior horn of alateral ventricle.

Meningoencefalocele


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Photograph of an infant with a large meningoencephalocele in the occipital area.


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Sonogram of a normal fetus at 12 weeks' gestation (left) and a fetus at 14 weeks'

gestation showing acrania and meroanencephaly (right).


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Photograph of an infant with

microcephaly, showing the typical

normal-sized face and small calvaria.

Microcefalia condio

relativamente incomum

Subdesenvolvimento do

encfalo e do crnio

Pode resultar de fechamentoprematuro das suturas

cranianas

Etiologia geralmente incerta


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, Photograph of an infant with hydrocephalus and bilateral cleft palate. B and C, Photographs showing the

brain of a 10-year-old child who had developed hydrocephalus in utero as a result of aqueduct stenosis. The

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