Development of NS

Question 1

When does the development of the nervous system begin?

Answer 1

3rd week post-conception

Question 2

How do genetics influence the development of the NS?

Answer 2

Sequence
Dendritic and axonal development
Interconnections and development of receptors and NTs

Question 3

What environmental factors may influence the development of the NS? (hint - two groups)

Answer 3

Intrauterine - PICU, alcohol, CMV, Rubella, placental function
Extrauterine - nutrition, toxins, emotional and social factors, drugs and alcohol

Question 4

What are the phases of NS development?

Answer 4

1. Embryonic (conception to week 9)
2. Foetal (week 9 to 40/42
3. Postnatal (til adolescence)

Question 5

What is the process by which the embryo goes from two layered to three layered?

Answer 5

Gastrulation (embryonic stage of development)

Question 6

What are the components of the two layered embryo?

Answer 6

Epiblast
Hypoblast

Primitive streak and node

Question 7

What direction does the migration of cells from the two layered embryo occur?

Answer 7

caudally

Question 8

What are the layers of the embryo at the end of gastrulation?

Answer 8

1. Ectoderm
2. Mesoderm
3. Endoderm

Question 9

What structures and derived from the Ectoderm layer?

Answer 9

Skin
Nails
Hair
Neural

Question 10

What structures are derived from the mesoderm layer?

Answer 10

Bone
Muscle
Cartilage
Vascular

Question 11

What structures are derived from the endoderm layer?

Answer 11

Respiratory and GI systems

Question 12

When roughly does the formation of the neural tube from the neural plate occur?

Answer 12

days 20-27

Question 13

What are the main occurrences in the foetal development phase?

Answer 13

Lissencephalic –> Sulcal and Gyral
Neuronal Migration to form 6 cortex layers
Networking

Question 14

Describe how the brain goes from lissencephalic to sulcal and gyral

Answer 14

Week 8-26 - formation of primary sulci
Week 30-35 - secondary
Week 36-postnatal - tertiary

Question 15

What are the main components formed for networking during the foetal phase?

Answer 15

Axons (takes signals from the neural cells)

Dendrites (delivers signals to the neural cells)

Question 16

What are the main occurrences during postnatal development?

Answer 16

Neuronal cell death
Myelination (mainly first two years)
Experiences - evolve 4 components of brain
Reorganisation at teenage years very important

Question 17

What occurs during myelination?

Answer 17

oligodendrocytes wrap around axons and form myelin sheaths to increase axonal conductivity and integrity.

Question 18

What direction does myelination occur?

Answer 18

top to bottom and back to front

Question 19

Why does reorganisation occur during teenage years?

Answer 19

Gonadal hormones - brain is full of steroid receptors

Question 20

What happens during the reorganisation in teenage years?

Answer 20

Emotional and cognitive changes
Synapse elimination
Increase in white matter
Change in NTs

Question 21

What is anencephalopthy?

Answer 21

Failure of formation of neural tube from neural plate.

Incompatible with life.

Question 22

What is Holoprosencephalopthy?

Answer 22

Failure of vesicle formation from neural tube.

Can be lobar, semilobar or alobar.

Question 23

What are the three types of myelination disorder?

Answer 23

Hypomyelination
Dismyelination
Demyelination

Question 24

Give an example of a demyelination disorder.

Answer 24

Pelizaeus Merzbacher - PLP1