DEVELOPMENT OF THE NERVOUS SYSTEM

Question 1

what are the 4 stages of nervous system development?

Answer 1

gastrulation
neurulation
nervous system patterning
neurogenesis

Question 2

what is the neural plate?

Answer 2

A thickening of ectodermal layer created by responses to growth factors released from the notocord

Question 3

what cell types form the components of the peripheral nervous system?

Answer 3

neural crest cells

Question 4

what day does the anterior neurophore close?

Answer 4

day 25

Question 5

what day does the posterior neurophore close?

Answer 5

day 28

Question 6

failure of the anterior neurophore to close leads to…

Answer 6

anencephaly

anencephalocele

Question 7

failure of the posterior neurophore to close leads to…

Answer 7

spina bifida

Question 8

what percentage of neural tube defects are related to folate?

Answer 8

70%

Question 9

what factor is secreted by the floorplate cells of the neural tube?

Answer 9

sonic hedgehog

Question 10

what factor is secreted by the roof plate cells of the neural tube?

Answer 10

BMP

Question 11

sonic hedgehog is responsible for the formation of which type of neurone?

Answer 11

motor

found in highest concentrations at ventral end of neural plate

Question 12

BNP is responsible for formations of which type of neurone?

Answer 12

sensory

found at highest concentrations at dorsal end of neural plate

Question 13

what type of embryonic cells give rise to the cerebrum?

Answer 13

Telencephalon

Question 14

what type of embryonic cells give rise to the hind brain?

Answer 14

Mesencephalon

Question 15

how is the nervous system developed along the anterior / posterior axis?

Answer 15

FGF - secreted by cells in the stem zone
Retinoic acid - made by somites in response to FGF

concentration gradients of both molecules determine differentiation potentials of cells in that local area

Question 16

how are the cerebral hemispheres divided during embryogenesis?

Answer 16

Via gradients of sonic hedgehog and FGF

Question 17

what is the function of hox genes in nervous system development?

Answer 17

help pattern the anterior - posterior axis

combinations of hox genes are turned on and off in response to different morphogen gradients

Question 18

Par3, Par6 and aPKC are all types of which family of proteins?

Answer 18

Apical base proteins

Question 19

what is apical aposition?

Answer 19

The process by which neural progenitor cells undergo differentiation into neurones, by losing their apical tip proteins

Question 20

what is craniorachischisis?

Answer 20

severe type of NTD in which both the brain and spinal cord fail to close

Question 21

what is encephalocele?

Answer 21

sac-like protrusions of meninges through a hole in the skull (recognised in a picture as a big mass coming off a babies head)

Question 22

at resting membrane potential, the membrane is very permeable to which ion?

Answer 22

K+

Question 23

which ion is responsible for the setting of the resting membrane potential?

Answer 23

K+

Question 24

what cell types are responsible for production of CSF?

Answer 24

choroid plexi of epindymal cells

Question 25

what percentage of CSF is produced by the lateral ventricles?

Answer 25

70%

Question 26

what percentage of CSF is produced by the third ventricle?

Answer 26

20%

Question 27

what percentage of CSF is produced by the fourth ventricle?

Answer 27

10%

Question 28

what is the recommended daily doseage of folic acid 3 months before and for the first 3 months of pregnancy?

Answer 28

400ug/day

Question 29

what are the consequences of too much folate in the diet?

Answer 29

folate transporter in choroid plexus blocked can lead to early onset dementia

Question 30

what is the average volume of CSF in an adult?

Answer 30

140-270ml

Question 31

how much CSF is produced per day in an adult?

Answer 31

600-700ml

Question 32

what is tethered spinal cord syndrome?

Answer 32

complication of open SB in which cauda equina becomes entangled within spinal cord coverings, causes paralysis as growth stretches spinal cord

Question 33

in the case of a meningomyelocele, what substance is damaging the nerves exposed in the cele?

Answer 33

Amniotic fluid - foetal urine

Question 34

what percentage of pregnancies are insensitive to folate?

Answer 34

33% (one third)

Question 35

what percentage of spina bifida cases go on to develop hydrocephalus?

Answer 35

50%

Question 36

which two genes are functionally analogous to the hox genes in terms of patterning of cerebral development?

Answer 36

Emx and Otx

Question 37

at approximately what day does the cerebral cortex start to develop?

Answer 37

week 8

Question 38

why is CSF drainage critical to normal cerebral functioning?

Answer 38

we need to drain around 400ml per day to maintain constant level of CSF

Question 39

why is drainage of CSF described as an active process?

Answer 39

ependymal cells are a type of simple columnar glial cell that line the ventricles. They waft CSF out of the ventricles into sub arachnoid space. Lack of ependymal cells can produce congenital hydrocephalus

Question 40

what is the difference between dietary folate and folic acid?

Answer 40

dietary folate > 5-methyl-THF folic acid > Dihydrofolate methyl group in dietary folate used for DNA methylation. folic acid doesn't have that!

Question 41

along with folate, which vitamin is needed for efficient folate function?

Answer 41

Vitamin D