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RB Y2 Child Health > Development of Neurons > Flashcards

Development of Neurons Flashcards

1
Q

when does human brain development begin

A

3rd post conception week

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2
Q

what factors influence the intrauterine environment

A

maternal health and disease

insults which may be continuous/episodic throughout pregnancy (eg alcohol, cytomegalovirus)

placental function and foetal nutrition

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3
Q

what factors influence the extrauterine environment

A

physical factors eg nutrition

emotional and social factors

exposure to alcohol, drugs etc

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4
Q

when is the embryonic period

A

conception to week 9

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5
Q

describe the development during the embryonic period

A

at first there is a 2 layered embryo - epiblast and hypoblast (epiblast becomes us and hypoblast forms sac, placenta and cord etc)

epiblast forms primitive streak and primitive node

cells migrate through streak and then rostro-caudal migration

this is determined by nodal signalling

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6
Q

gastrulation

A

results in the development of a 3 layered embryo (germ layers)

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7
Q

describe the development of the 3 germ layers

A
  • Ectoderm – skin, nails, hair and neural tissue
  • Mesoderm – muscle, bone, cartilage and vascular system
  • Endoderm – gut and respiratory system
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8
Q

when does the neural tube form

A

day 20-27

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9
Q

describe the formation of the neural tube

A

neural progenitor cells form the neural plate, which forms the neural groove and then neural tube

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10
Q

describe the further development of the neural tube

A

neural progenitors line the inside of the tube - form the ventricular zone

hollow centre of the tube becomes ventricular system and central channel of spinal cord

anterior/rostral tube becomes the brain

caudal tube becomes the spinal cord

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11
Q

define neural patterning

A

cells acquire distinct identities according to their specific spatial positions

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12
Q

describe neural patterning in the mature neocortex

A

the mature neocortex has distinct functional and strucutral areas, and genes are expressed differently in these areas

there is continuous and complex refinement

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13
Q

give an example of neural patterning in the mature neocortex

A

signalling molecules Emx2 and Pax6

  • a high concentration of Pax6 and low of Emx2 inducecs progenitor cells to differentiate into motor neurons
  • the converse induces visual cortical neurons
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14
Q

when is the foetal development period

A

week 9 to 40/42 (term)

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15
Q

how is the brain initally formed in the foetal development period

A

smooth in contour - lissencephalic

gradually develops sulci and gyral pattern

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16
Q

why is the development of gyri and sulci required

A

to accomodate the proliferating neuronal populations

17
Q

describe the division of the NPC in the ventricular zone

A

divide intially symmetrically then asymmetrically

  • In symmetrical cell division, both daughter cells are progenitor (stem) cells
  • In asymmetrical cell division, one progenitor (stem) cell is produced and one neuron (cannot divide further)

progenitor cells remain in VZ and continue to divide, and neurons migrate to their place in the developing neocortex

18
Q

what are the 3 ways in which neurons migrate to the cortex from the ventricular zone

A

somal translocation

radial glial guides

tangetial migration and signalling pathways

they end up in an orderly 6 layered structure with an inside out arrangment of migrated neurons

19
Q

what do neurons develop once they reach their target cortical regions

A

axons - longer and communicate with other neurons

dendrites - gather information and transmit to neurons

20
Q

programmed neuronal cell death

A

babies are made with all the neurons they need- half of these will die (apoptosis), mostly prenatally

21
Q

synaptic exuberance

A

development of connections between the neurons

22
Q

synpatic pruning

A

axons and dendrites

process of synapse elimination that occurs

23
Q

oligodendrocytes

A

form myelin sheaths in the CNS

(schwann cells in the PNS)

24
Q

post natal development

A

limited neuronal proliferation from the VZ

  • olfactory bulbs
  • dentate gyrus of the hippocampus
  • oligodendrocytes

myelination

25
Q

when does myelination occur

A

post natally

26
Q

myelination

A

OPC develop processes which wrap around axons to form myelin sheaths

  • increase axonal conduction rates

also maintain axonal integrity, survival, neuronal size and axonal diameter

27
Q

when does myelination mainly occur

A

first 2 years of life

ongoing into 20s

28
Q

why is there an increased risk to health during adolescence

A

risk taking behaviour and extreme emotions

29
Q

effect of hormones on development of the brain during adolescence

A

Pubertal hormones affect brain restructuring and result in permanent reorganization

Hormones have different effects on the HPA axis in males and females:

  • Oestrogens make girls more prone to stress
  • Androgens are supposed to make boys more resilient to stress
30
Q

how is the nerichment and deprivation effect illustrated

A

monocular visual deprivation:

  • This is associated with altered patterns of organization within the primary visual cortex
  • When both eyes are stimulated pathways known as ocular dominance columns develop equally
  • If one eye is blocked, the bands/columns representing the deprived eye shrink and the inputs from the active eye invade and subsume territory in the PVC normally occupied by the blocked eye
  • Squint development
31
Q

what is faults in neural tube formation associated with

A

spina bifida and anencephaly

32
Q

what is failure of the brain vescile to form called

A

holoprosencephaly

33
Q

PLP1 related disorders

A
  • The PLP1 gene encodes a transmembrane proteolipid protein, the predominant myelin protein present in the CNS. It is responsible for compaction, stabilization and maintenance of myelin sheaths, oligodendrocyte development and axonal survival
  • Located on the X chromosome (X-linked inheritance)
  • Mutations in the PLP1 gene cause a spectrum of disorders, Pelizaeus-Merzbacher is the most severe
  • Presents in infancy/early childhood with nystagmus, hypotonia and cognitive impairment. Progresses to severe spasticity and ataxia
  • Shortened life span
  • Spastic paraparesis 2 manifests as spastic paraparesis with/out CNS involvement and usually normal life span
34
Q

impact of malnutrition on brain development

A

impact on brain growth and volume

impact on myelination

a lack of energy and deprivation leads to a lack of post natal stimulation and experiences

RB Y2 Child Health (1 decks)

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