Embryology of CNS & PNS Flashcards
developing egg
oocyte
cellular process that replicates chromosomes and produces two identical nuclei in preparation for cell division
mitosis
gastrulation
formation of germ layers
formation of endoderm and ectoderm
by 2nd week
mesoderm bw/ ect and end
by 3rd week
future center where the sc and bs line up
notocord
where does the CNS form from
neural fold, deepens and pinches off form the outside
what is the neural fold made of
tube of ectoderm
creates the outer skin layers, nervous system and sense organs
ectoderm
are the outer and inner ear made of ectoderm?
YES
Makes skeletal structures, circulatory structures, meninges, notochord, reproductive organs and cartilage
mesoderm
what are the ossicles and temporal bone made of
mesoderm
what do we have in avs that uses air?
ET (air to nasopharynx), middle ear and mastoid air cells
air filled spaces for tubes related to our ear come from endoderm
makes the digestive canal and respiratory organs (viscera)
endoderm
what are the middle ear, mastoid cavities and ET made of?
endoderm
can genetic issues only affect one germ layer and not the others
yes
when is it called an embryo
first 8 weeks
when does it turn to a fetus
when it forms human type shape
what occurs in the 3rd week of CNS development
ectoderm neural placode, folds, then groove at dorsal midline
how does the neural tube fuse?
zips in both caudal and rostral directions
which end of the neural tube fuses first
rostral does 2 days before caudal
what is the superior opening of the neural tube
cranial/rostral neuropore
what is the inferior opening of the neural tube
caudal neuropore
crest cells left behind by each neural fold makes
form things in PNS (sensory neurons of dorsal root ganglia, some CN’s, schwann cells, etc.)
what are ectodermal placodes
specialized regions of cranial ectoderm that create special sense organs and majority of the sensory neurons in the head
separates the neural tube into dorsal half and ventral half
sulcus limitans
primarily sensory
alar/dorsal plate (dorsal horns)
derivatives are motor
basal/ventral plate (ventral horns)
do alar and basal separation continue in the BS?
yes
sensory area of skin supplied by a single afferent spinal nerve and by afferents of cranial nerve V
dermatome
failure of caudal neuropore to close
spina bifida
spina bifida can lose
sensory and motor function at and below level of lesion
what is the least severe type of SB
Oculta
this SB is marked with a tuft of hair over it
oculta
is SB Oculta protected?
no, vertebrae is not covering the area just skin
which sb has meninges that protrude out in a saclike cavity over the defect
SB Meningocele
bulge of csf and dura in this SB
meningocele
sc and meninges protrude out in a saclike cavity over the defect
myelomeningocele sb
what is the difference between myelomeningocele and meningocele sb?
there is a larger gap b/w vertebrae, more CSF and dura present in the saclike cavity and the sc is also in it
which SB do we see the most deficit in motor and sensory function?
myelomeningocele because because they don’t transmit info properly and can get very damage being outside of the bony cavity
what can prevent sb?
diet and health of mom, no toxicity
what accomponies myelomeningocele?
arnold-chiari malformation
Herniation of cerebellum and caudal brainstem through the foramen magnum and may obstruct the flow of cerebrospinal fluid, producing hydrocephalus.
arnold-chiari malformation
what is the opening between the skin and meninges?
dural sinus, can be surgically repaired
how does crania bifida form
when rostral neuropore fails to close
can crania bifida children survive?
no, not conducive for post natal life
a result of this is anencephaly
crania bifida
are we able to detect and prevent neural deficits?
dietary supplements can reduce cases of SB and crania bifida
we can detect neural tube defects through ultrasound or other prenatal tests
Sufficient folic acid is needed in the maternal diet
this can occur before women know they are pregnant
neurulation (formation of nervous system)
where future bs meets future sc
cervical flexure
at level of future midbrain, remains as bend bw axis of brainstem and axis of cerebrum in adult CNS
cephalic flexure
on poster/dorsal surface in area of pons and 4th ventricle
pontine flexure
forebrain
prosencephalon
encephalon
brain
what are the divisions of prosencephalon
telencephalon & diencephalon
cerebrum/cerebral hemispheres & lateral ventricles
telencephalon
thalamus and surroundings and 3rd ventricle
diencephalon
midbrain and cerebral acqueduct
mesencephalon
hindbrain
rhombencephalon
what are divisions of thombencephalon
metencephalon and myelencephalon
cerebellum and pons and part of 4th ventricle
metencephalon
medulla and part of 4th and central canal
myelencephalon
no brain
anencephaly
how are ventricles formed
by the cavity of the neural tube
abnormality of cns with partial/incomplete development of prosencephalon (forebrain) and there is no separation of R and L diencephalon and telencephalon structures
holoprosencephaly
single midline eye abnormality
holoprosencephaly
is holoprosencephaly fatal?
yes
what is the nervous system highly impacted by
genetic changes
what percent do diseases increase to if neuromuscular system, eyes and ears are included
80-90%
single mutant gene
it is transmitted from one or two people to the offspring
monogenic disorder
single mutant gene and there is an outside of the body environmental factor
exogenous environmental factors
mutlifactorial disorder
Excess, lack or structural alteration of one or more of the 23 pairs of chromosomes
- e.g., Down syndrome (trisomy 21)
nonmendelian chromosomal aberrations
alteration in mitochondrial DNA
- nonmendelian; mainly maternal transmission
- affects enzymes of mitochondria
mitochondrial transmission of disease
how do newborns nervous systems function
at the brainstem-spinal level
higher centers are not yet myelinated
what functions do we monitor in infants?
control of respiration
control of body temp
regulation of thirst, fluid balance and appetite
what are examples of drive related behaviors
rooting, sucking, swallowing, grasping etc.
describe the moro reflex
called a startle reflex because it usually occurs when a baby is startled by a loud sound or movement. In response to the sound, the baby throws back his/her head, throws out his/her arms and legs, cries, then pulls his/her arms and legs back in. Sometimes, a baby’s own cries can startle him/her - initiating this reflex. The Moro reflex lasts until the baby is about 5 to 6 months old
inability to break down ganglioside which accumulates in neurons causing them to swell, burst
lysosomal storage disease
tay sachs disease
inability to break down sphingomyelin which accumulates in neurons causing them to swell & burst
neimann pick disease type a
list some symptoms of NPD Type A
seizures, hypersensitivity to touch, sudden loss of muscle tone, progressive loss of early motor skills
what is the survival rate for NPD T-A
death by 2-4 yrs
inability to metabolize cholesterol and other lipids properly
* excessive lipids in the brain
NPD T-C
what is the survival rate for NPD T-C
mid to late teens
signs of NPD T-C
learning difficulties and progressive dementia
seizures
tremors
inability to metabolize phenylalanine
phenylketonuria
what is the survival rate of hurler syndrome
early teens due to heart disease
damage of hear valves and heart murmurs are common
hurler syndrome
is there treatment for neonatal metabolic diseases?
dietary restriction of specific amino acids
* oral supplementation of specific vitamins
* bone marrow transplant to supply stem cells to make missing enzyme/s
what is the importance or difficulty with genetic metabolic disorders?
Or what makes them so severe and hard to treat?
because their at the cellular level where something like the lysosomes dont have the right enzymes to
to break things down and as cells die and they cannot be replaced fast enough causing function
to decrease to the point of usually not a full life past childhood.
