Development of nervous system Flashcards
1
Q
What is a brief summary of the nervous system developmental phases
A
- fertilised egg (zygote)
- day 4: morula
- day 5: blastocyst
- day 13-19: gastrulation (formation of groove - ectoderm, mesoderm, endoderm) neural plate
- day 20: uneven rates of cell division from neural groove
- day 22: neural tube, neurulation
- day 24: 3 divisions forebrain, mid + hind
- 3-4 weeks: bend in tube -cervical flexure
- 6 months: ridges in cortex apparant
- 9 months: similar to adult brain
2
Q
Which germ layer does the NS develop from?
A
ectoderm
3
Q
How does a tube become a brain?
A
-channel between spinal cord and brain partially closes, fluid pumped in, brain swells, hydrostatic pressure, differential rates of cell growth
4
Q
How many neurons do humans generate per minute during peak cell proliferation?
A
250,000
5
Q
Where do neurons come from?
A
- during gastrulation, cells in ectoderm around midline receive chemical signal
- forms notochord
- some develop into neural precursor cells
- neural stem cells divide
- migration using growth cones
- differentiation
6
Q
types of axonal growth cones
A
diffusible agents: chemoattractants/chemorepellants
non-diffusible: contact attractants/repellents
7
Q
the majority of neurons that compose the adult brain are presented as early as…
A
7th prenatal month
