L&D 2/2 Flashcards
What is differential brain development?
It takes different amounts of time for different parts of the brain to grow to their full size
By how much does the brain increase in size from birth to teenage-hood?
4x
What % of the body is the brain and what % of the O2 inhaled does it use?
2% and 20%
What % of an infant’s body weight is its head?
25%
How many neurones does the brain have at birth?
100 billion+
What are the 3 trimesters of prenatal development?
Zygote - 2wks
Embryo - 3-8wks
Foetus - 8wks-birth
What is the germinal stage?
Where the zygote is formed and implants in the uterus wall
What is the embryonic stage?
amniotic sac, placenta and umbilical cord develop
What are the 3 primary germ layers and what parts of the infant do they become?
endoderm - digestive system
mesoderm - muscles, skeleton
ectoderm - CNS
What is neurulation?
Where the neural tube (formed from the neural fold) forms the brain and the spinal cord
What is neurogenesis?
Where neurones are produced for specific functions
What forms the hindbrain, midbrain and forebrain?
The cranial end of the neural tube
When does neurogenesis and cell migration continue until?
6 months of gestation
How many neurones are added every minute in neural proliferation?
250,000
What is the foetal stage?
3months to 27wks 3m - all body parts present 5m - reflexes 6m - eyes open and close, sulci+gyri appear 22-26wks - viability
What are the 6 stages of brain development?
- neurogenesis
- migration
- differentiation
- aggregation - formation of specialised regions by neurones
- synaptogenesis
- Competition among synapses - synaptic pruning
What is the last thing to develop in a foetus?
The cortex
What are the 3 milestones of prenatal development?
12wks - breathing established
23wks - sleep-wake cycle established
30wks - 70%-80% REM sleep
What are the milestones of prenatal motor development?
7wks - movement detected by ultrasound 8wks - startle response 9wks - arm and leg movements 10wks - head movements, hand-face contact 12wks - move fingers independently 14wks - hand rotation 15wks - 15 different movement patterns 16wks - movements felt by mother 18wks - eye movements 17-24wks - quiescent period (no movement) 24wks - thumb sucking 26wks - eyes open
What is teratology?
Study of congenital abnormalities and abnormal formations in foetuses
What is a teratogen?
An agent that causes developmental deviations
Give a few examples of teratogens and their effects
drugs (aspirin - low IQ, poor motor control, caffeine - risk of miscarriage, heroine/cocaine - addicted babies)
smoking (spontaneous abortion, prematurity, low weight)
disease
radiation (cell death, chromosome injury)
metals (lead, mercury)
parental factors (age - downs’ syndrome, diet, emotional state)
How does the Zika virus affect foetuses?
can cause microecephaly, pre-term birth and miscarriage
What is microecephaly?
bellow average head size ( less than 31.5-32cm at birth)
poor feeding
seizures
developmental delay
What is lissencephaly?
‘smooth brain’ - lacking gyri and sulci
caused by defective neural migration due to viral infection OR genetic anomaly
seizures
developmental disabilities
What if foetal alcohol syndrome? What differnce does it make if taken in 1st trimester vs. 3rd?
distinct facial features CNS damage learning disabilities 1st trimester - impaired brain cell organisation 3rd trimester - impaired brain function
What did Kelly et al. (2009) say about mild drinking during pregnancy?
It could have positive effects (1-2 units p/w)
What is the deal with Thalidomide?
Drug given to help with morning sickness in 1950s-60s BUT
inhibits blood vessels around day 24-28 causing limb deformation
~10,000 cases in 46 countries