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34 Cards in this Set
- Front
- Back
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What % of newborns have congenital CNS malformations?
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1%
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What % of infant deaths are due to CNS malformations?
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40%
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What do the majority of CNS malformations causing infant deaths consist of?
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Defective closure or rupture of the neural tube - 90%
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What are the other 10% due to?
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Abnormal neuronal and glial proliferation, migration, and organization.
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What are the 3 general periods of CNS development?
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1. Induction
2. Cell proliferation/migration 3. Cellular organization and architectonics |
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When is the induction period?
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From conception to 1.5 months gestation
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When is the period of cell proliferation and migration?
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From 2nd month gestation until 6 months postnatal
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When is the period of cell organization and architectonics?
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6months gestation to 2nd postnatal year
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What has happened by the end of the 1st week of gestation?
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Uterine implantation of the embryo
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What has happened by the end of the 2nd week of gestation?
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The 3 germ layers have formed
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What forms in the midline of the ectoderm at the end of the 2nd week?
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The neural plate
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What happens to the neural plate during week 3 of gestation?
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It deepens between lateral neural folds to form the neural groove.
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What do the lateral folds fuse to form?
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The neural tube with neural pores at each end
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What happens to the neural tube?
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It closes off the pores, diverticulates, and flexes.
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What are the 4 components of the neural tube after flexion?
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1. Forebrain: cerebrm/thalamus
2. Midbrain 3. Hindbrain: pons cerebellum and medulla 4. Spinal cord |
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What do the neural crest cells develop into? (6 things)
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-Dorsal roots
-Ganglia -Schwann cells -Melanocytes -Adrenal medulla -Mesenchymal tissues |
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What does the caudal cell mass at the lower end of the neural tube form?
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Conus medullaris
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What forms the vertebral bodies and arches around the neural tube?
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Mesodermal somites
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What is the Induction theory?
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The theory that neural axial development depends on induction by the adjacent germ layers and notochord.
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What will failure of dorsal induction lead to? When?
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Posterior midline defects - this should occur during weeks 3-4 of gestation.
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What will failure of ventral induction lead to? When?
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Anterior midline defects - this should occur during weeks 5-6
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What does "proliferation" in the proliferation/migration phase consist of?
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Proliferation of undifferentiated germinal cells in the neural tube in the periventricular region.
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What do the cells do after proliferating in the periventricular region?
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Migrate centrifugally in waves to form neurons and glia in the cortex and white matter.
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When does neuronal proliferation cease in the cerebellum?
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In the postnatal 6th month
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When is neural migration completed?
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By 1.5 years postnatal
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What happens to the surface of the brain during the completion of neural migration?
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Development of gyri/sulci - the surface becomes convoluted.
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When do the primary sulci form? Which sulci are these?
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-5th gestational month
-Central sulcus -Sylvian fissures |
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So what is the timeframe of the period of cell proliferation and migration?
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2nd month of gestation to the 6th month postnatal
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When is the period of cell organization and architectonics?
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6th month gestation to 2nd postnatal year
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What takes place in the period of cellular organization and architectonics?
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Construction of the brain - alignment and connection of neurons.
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How is functional interaction established in the brain?
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By formation of synapses
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What else happens to improve nerve impulse conduction during this phase?
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Myelination
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When does myelination begin and end?
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Begins at 6 mo gestation
Mostly done by 2 yrs postnatal All done by 4 yrs old |
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How long is neural plasticity present?
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Throughout life
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