9: Nervous system development Flashcards
When does the brain begin to develop?
3rd week
What are two factors affecting brain development?
Genetics
Environment
What is a metabolic disease which can cause developmental delay or regression?
PKU
Exposure to what environmental factors can affect brain development?
Alcohol, drugs
Nutrition in general
Viruses, bacteria
When is the embryonic period?
Conception to Week 9
When is the foetal period?
Week 9 to Birth (on average Week 40)
What are the two initial layers of an embryo?
Epiblast
Hypoblast
Cells migrate through what to form the mesoderm?
Primitive streak
What are the three layers remaining after cells have migrated through the primitive streak?
Epiderm
Mesoderm
Endoderm
Which germ layer develops into bone, muscle, cartilage and the vascular system?
Mesoderm
Which germ layer develops into the skin, hair, nails and nervous system?
Ectoderm
Which germ layer forms the skin, hair, nails and neural tissue?
Ectoderm
Which germ layer develops into the gut and respiratory system?
Endoderm
Why is it significant that the skin, hair, nails and brain develop from the same germ layer?
Neurocutaneous diseases e.g NF
What is the first neural structure to form?
Neural tube
What disorders occur if the neural tube doesn’t close properly during development?
Neural tube defects e.g spina bifida, anencephaly
What zone is found inside the neural tube?
What does the outside of the tube form?
Ventricular zone
Cerebral cortex, i.e the brain itself
The caudal part of the neural tube forms what?
Spinal cord
What is neural patterning?
Cells in the brain develop specific functions depending on their position
When is the foetal period?
Week 9 till birth
Why does the brain develop sulci and gyri?
Originally flat but needs to fit through birth canal, so folds to maximise surface area
Neurones ___ and then ___.
divide
migrate
Can neurons multiply once they have migrated?
No
Neurons migrate from the ___ of the brain to the ___.
ventricles to cortex
What are two types of process found in neurons which allow them to communicate with each other?
Dendrites
Axons (much bigger)
What percentage of neurons die off before birth?
50%
If division and migration are the important processes of the prenatal period, what is the important process in the postnatal period?
Myelination
What is myelin?
Fatty substances which insulates axons (allows nerve impulses to travel further and quicker)
What directions does myelination occur in?
Bottom to top
Back to front
Apart from myelination, what is required for the brain to develop in the postnatal period?
EXPERIENCE
i.e brain input
In the postnatal period, a lack of ___ deprives the brain of the input it needs to develop.
experience
Brain development is ___ by positive inputs.
enriched
What period of life is very important for brain development?
Adolescence
(10-19 years-ish)
What process describes the loss of neurons which aren’t used in order the maximise the efficiency of the brain?
Synaptic pruning
Why do your emotions and brain function change so much during adolescence?
Anatomical reorganisation
Supposedly…
oestrogen makes girls (more / less) stressed
androgen makes boys (more / less) stressed.
oestrogen - more
androgen - less
Are brain insults in the first weeks of gestation compatible with life?
No - foetus will spontaneously abort
What embryological structure causes major disease if it doesn’t form correctly?
Neural tube
Name two neural tube defects.
Anencephaly (no brain)
Spina bifida
What process, important for development in the postnatal period, may be disordered?
Myelination
What are three types of myelination disorder?
Hypomyelination (not enough)
Dysmyelination
Demyelination
What dietary problem has a huge impact on brain development?
Malnutrition
Malnutrition has an effect in which period of life?
All of them
prenatal, postnatal, adolescence, adulthood, old age
