Embryology Flashcards

1
Q

what are the three layers of the derm layers?

A

ectoderm
mesoderm
endoderm

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2
Q

what layer of the term trilaminar plate forms the nervous system?

A

ectoderm

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3
Q

what layer of the term trilaminar plate forms the bone?

A

mesoderm

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4
Q

what layer of the term trilaminar plate forms the gut?

A

endoderm

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5
Q

what layer of the term trilaminar plate forms the lungs?

A

endoderm

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6
Q

what layer of the term trilaminar plate forms the epidermis ?

A

ectoderm

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7
Q

what layer of the term trilaminar plate is in contact with the yolk sac?

A

endoderm

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8
Q

at which week does the CNS start to appear?

A

3rd week

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9
Q

what is formed from the thickening of the ectoderm anterior to the primitive node?

A

neural plate

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10
Q

what causes the neural plate to form?

A

primitive node sends out signals

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11
Q

what are the thickened edges of the neural plate called?

A

neural folds

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12
Q

what day does the neural plate start to fold ?

A

day 20

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13
Q

where is the first area the neural tube starts to fuse?

A

in the middle

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14
Q

at what day does the anterior and posterior neuropore both close ?

A

day 27

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15
Q

what neuropore closes first?

the anterior or posterior

A

the anterior closes first at day 25

the posterior closes at day 27

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16
Q

what is another name for the anterior neuropore ?

A

the rostral

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17
Q

before the neural tube closes, is it in contact with amniotic fluid ?

A

yes

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18
Q

what is the depression down the neural tube called?

A

neural groove

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19
Q

what shape do the cells in the neural groove change from and to ?

A

columnar -> wedge shaped

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20
Q

what are the three main neural tube defects ?

A

Anencephaly
Encephalocoele
Spina bifida

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21
Q

what defect occurs during anencephaly ?

A

failure of the anterior neuropore closure

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22
Q

what would result in the anterior neuropore not closing?

A

the neural tube is in contact with the amniotic fluid so the skull and brain can’t form properly

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23
Q

can’t people with anencephaly survive?

A

no

- usually still birth

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24
Q

is anencephaly more common in males or females ?

A

x4 common in females

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25
Q

what defect results in encephalocoele?

A

when the rostral neuropore doesn’t close properly and cerebral tissue herniates through the skull defect

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26
Q

in what areas is the skull defect most common in encephalocoele?

A

occipital and fronto-nasal area

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27
Q

what common defects post birth does encephalocoele result in due to the areas of brain which is affected?

A

vision impairment and emotion and cognitive impairment

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28
Q

what do the degree of neurological deficits depend on ?

A
  • part of brain affected

- area of brain affected

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29
Q

out of the three most known neural tube defects which one is most common?

A

spina bifida

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30
Q

is anencephaly and encephalocoele common?

A

no they are rare

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31
Q

what defect results in spina bifida ?

A

defect in the closure of the caudal (posterior) neuropore and the vertebral arches don’t fuse

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32
Q

are there different subtypes of spina bifida ?

A

yes three main subtypes

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33
Q

what are the three sub types of spina bifida ?

A

meningocele
meningomyelocle
myeloschisis

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34
Q

which of the three subtypes of spina bifida are most severe?

A

myeloschisis

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35
Q

has the incidence of spina bifida been increasing or decreasing ?

A

decreasing

36
Q

state two reasons why spina bifida incidence is decreasing?

A
  • folic acid supplements

- prenatal screening

37
Q

what is the rarest type of spina bifida ?

A

meningocele

38
Q

what three tests can be done prenatal to test for spina bifida ?

A
  1. blood test for alpha fetoprotein (increased)
  2. amniocentisis
  3. ultrasound
39
Q

What three risk factors are there for neural tube defects?

A
  1. genetic predisposition
  2. nutritional
  3. environmental
40
Q

how many primary vesicles are there?

A

3

41
Q

what are the three primary vesicles called?

A

prosencephalon
mesencephalon
rhombencephalon

42
Q

what week do the primary vesicles form?

A

4th week

43
Q

what week do the secondary vesicles form?

A

5th week

44
Q

what are the three flexures in the neural tube are there?

A

cephalic
pontine
cervical

45
Q

what structures does the cephalic flexure divide?

A

midbrain and hindbrain

46
Q

what structures does the pontine flexure divide?

A

the two vesicles in the hindbrain

47
Q

what structures does the cervical flexure divide?

A

the hindbrain and spinal cord

48
Q

what structures are formed from the telencephalon ?

A

cerebral hemispheres, hippocampus, basal ganglia

49
Q

what structures are formed from the diencephalon ?

A

thalamus
hypothalamus
pituitary gland
pineal gland

50
Q

what structures are formed from the mesencephalon ?

A

superior and inferior colliculi

51
Q

what structures are formed from the metencephalon ?

A

cerebellum and pons

52
Q

what structures are formed from the myelencephalon ?

A

medulla

53
Q

what week does CSF start to be formed?

A

5th

54
Q

what produces CSF?

A

choroid plexus

55
Q

in which ventricle does the CSF drain into the subarachnoid space?

A

4th ventricle

56
Q

where does the CSF reabsorbed back into venous system ?

A

arachnoid villi

57
Q

is CSF continually being replaced?

A

yes

58
Q

what is the condition when there is a blockage in the ventricles and CSF can’t circulate properly?

A

hydrocephalus

59
Q

what ventricle is most commonly blocked during hydrocephalus ?

A

cerebral aquaduct

60
Q

what are some causes of hydrocephalus ?

A

genetic
prenatal viral infection
intraventricular haemorrhage
spina bifida cystica

61
Q

what cells are present as a single layer around the neural tube which go on to form neurons and glial cells?

A

neuroepithelial cells

62
Q

what four cells are produced from neuroepithelium in the CNS?

A

neuron
astrocyte
oligodendrocytes
ependymal cell

63
Q

which cell in the CNS is not produced by neuroepithelium ?

A

microglia

- which comes from mesenchymal cells

64
Q

what are the two types of astrocytes ?

A

protoplasmic

fibrous

65
Q

what is the function of astrocytes ?

A

maintains BBB and supports neurons

66
Q

which cells form the PNS?

A

neural crest cells

67
Q

state some structures the neural crest cells form?

A

dorsal root ganglia
sympathetic ganglia
parasympathetic ganglia

68
Q

at which month is the spinal cord the same length as the vertebrae?

A

3 months

69
Q

at birth what spinal vertebrae does the spinal cord finish at?

A

L3

70
Q

as an adult what spinal vertebrae does the spinal cord finish at?

A

L1

71
Q

what are the hills and depressions in the cerebrum called?

A
hills = gyrus 
depressions = sulci
72
Q

what are the hills and depressions in the cerebellum called?

A
hills = folia  
depressions = sulci
73
Q

what is the advantage of having sulci and gyri in the cerebrum?

A

increases surface area and hence more cells and information can be fitted in the small area of the brain

74
Q

what is the very rare disorder when sulci and grey don’t form on the brain?

A

lissencephaly

75
Q

what causes lissencephaly?

A

when there is defective neuronal migration

76
Q

what is polymicrogyria ?

A

when there are many small gyri

77
Q

what does polymicrogyria result in?

A

connection defects which results in neurological problems such as retardation, seizures and motor deficits

78
Q

what condition is caused by the zika virus ?

A

microcephaly

79
Q

what is the condition called when there is defected connection between the two hemispheres of the cerebrum ?

A

aegenesis corpus callosum

80
Q

what is the condition when there are CSF filled cysts in the cerebrum ?

A

porencephaly

81
Q

what condition results in large clefts or slits in the cerebrum ?

A

schizencephaly

82
Q

what condition results in the spinal cord being divided into two?

A

diastematomyelia

83
Q

what is a common cause of intellectual impairment in children?

A

maternal alcohol abuse

84
Q

why is the CNS vulnerable to defects form alcohol?

A

the CNS develops early in the 3rd week, therefore some women may not even realise they are pregnant so may continue drinking which could cause CNS defects

85
Q

what is the incidence of foetal alcohol syndrome per 1000?

A

1:1000

86
Q

what is the incidence of spina bifida per 1000?

A

1:1000

87
Q

as well as alcohol state some causes of intellectual impairment in children?

A
genetic (downs)
radiation 
infection 
birth trauma 
postnatal insults (meningitis)