Case 1 - NT defects and bipolar

Question 1

what are the the germ layers formed during gastrulation?

Answer 1

ectoderm
mesoderm
endoderm

Question 2

what does the ectoderm become?

Answer 2

skin and NS

Question 3

what does the mesoderm become?

Answer 3

connective tissue, bones and muscles

Question 4

what does the endoderm become?

Answer 4

lining of internal organs, GI tract and airways

Question 5

which germ layer if the neural plate derived?

Answer 5

ectoderm

Question 6

what induces the formation of the neural plate?

Answer 6

notocord

Question 7

what are the two openings called in the anterior and posterior neural tube? and at what point do they close?

Answer 7

neuropores
anterior - 25 days
posterior - 28 days

Question 8

what do neural crest cells differentiate into?

Answer 8

peripheral CNS

Question 9

which germ layer is the notocord derived from?

Answer 9

mesoderm

Question 10

what does the notocord eventually become?

Answer 10

nucleus pulposus of the intervertebral discs

Question 11

what germ layer are the somites derived from? and what do they become?

Answer 11

mesoderm - axial skeleton

Question 12

what two substances determine the dorsoventral axis of the neural tube?

Answer 12

SHH - from notocord - then floor cells

BMP - from epidermis - then roof plate cells

Question 13

what transcription factors are turned on by BMP? and what cell identities do these promote?

Answer 13

PAX 6/7 - sensory neurons

Question 14

what transcription factors are turned on by SHH? and what cell identities do these promote?

Answer 14

Olig 2 - motor neurons

Question 15

in what region does closing of the neural tube occur first?

Answer 15

cervical region

Question 16

a failure of the neuropores to close can result in which two neural tube defects?

Answer 16

anterior - anencephaly

posterior - spina bifida

Question 17

what two diffusible molecules (morphogens) are essential for the setting up of the anterior posterior axis?

Answer 17

FGF

retinoic acid

Question 18

where do neural progenitor cells differentiate?

Answer 18

apical surface (inner surface) of the neural tube

Question 19

in the later stages of development, neural progenitor cells switch to stem cell mode divisions - one daughter cell will remain a progenitor cell, what will the other cell become?

Answer 19

a neuron

Question 20

true or false - progenitor cells are polarised?

Answer 20

true

Question 21

what is critical for the correct placement of neurones and formation of normal tissue architecture?

Answer 21

acute loss of apical polarity of neural progenitor cells

Question 22

Where are the primary cilium and centrosome located in neural progenitor cells?

Answer 22

apical pole

Question 23

apical abscission of what leads to the differentiating neuron leaving the cell cycle?

Answer 23

primary cilium at the apical pole

Question 24

how does a pioneer axon reach its target?

Answer 24

responding to guidance cues

Question 25

Hoe many types of chiari malformation are there?

Answer 25

4 types
1 - only spinal cord and a possible a small amount of cerebellum (cerebellar peduncles) - most common - usually benign
2 - both spinal cord and cerebellum protrude into foramen magnum
3 - rare and most serious - cerebellum and brainstem stick out or herniate through an abnormal opening in the back of the skull
4 - incomplete or underdeveloped cerebellum

Question 26

name 4 distinctions between brainstem-spinal cord development and development of the cerebral cortex?

Answer 26

1. notocord does not control cerebral development
2. genetics - hox genes not expressed in head end, Emx and Otx only present in head end
3. Timing BS and spinal cord develop first
4. fluid system - high volume of CSF produced within cerebral cortex

Question 27

How is CSF involved in the migration of neurones in the cortex?

Answer 27

CSF externalises and reelin is expressed which promotes the migration of radial glial cells which new neurones require for their migration into the cortex

Question 28

What can greatly increase the chances of a NT defect?

Answer 28

lack of folic acid (vitamin B) in mother diet

Question 29

what are the types of spina bifida?

Answer 29

1. spina bifida oculta - dimple or tuft of hair above the defect
2. closed neural tube defects
3. meningocele - meninges and spinal fluid however no neural tissue
4. myelomeningocele - spinal cord/neural elements are exposed though opening in the spine - most severe

Question 30

what condition is commonly linked to spina bifida?

Answer 30

hydrocephalus - too much CSF

Question 31

what is the pharmacologically active component of sodium and semisodium valproate?

Answer 31

valproic acid

Question 32

At what age are people presumed to have the capacity to consent to medical treatment?

Answer 32

16

Question 33

what exceptions to the mental capacity act apply to 16-17 yos?

Answer 33

cannot make lasting power of attorney

cannot make an advanced decision to refuse treatment

Question 34

what are the 5 principals of the mental capacity act?

Answer 34

1. assume capacity
2. all practical support
3. unwise decision
4. best interests
5. least restrictive

Question 35

what is used to diagnose spina bifida - prenantally?

Answer 35

• during second trimester, maternal serum alpha fetoprotein (MSAFP) - abnormally high levels in mother blood stream indicates an open NTD
• ultrasound
• amniocentesis

Question 36

what causes the lemon sign?

Answer 36

decrease in intraspinal pressure in neonates with spina bifida - causing the brain to shift downwards - decreasing intracranial pressure - which pulls on the frontal bones (scalloping them in)

Question 37

what are the 5 primary brain regions and what are their derived structures

Answer 37

Forebrain:
-- telencephalon - cerebrum
-- diencephalon - thalamus and thalamic nuclei
Midbrain:
-- mesencephalon - midbrain
Hindbrain:
--metencephalon - pons and cerebellum
-- myelencephalon - medulla