Chapter 4: prenatal development Flashcards
What is organogenesis?
Process of organ formation starting from 10 weeks
What are the three phases of prenatal development?
- Zygote: fertilization - 2w
- Embryo: 2-10w
- Fetus: 10w-birth
How long does it take for a fertilized egg to implant in the uterus? How is the egg called when it implants?
7 days, it’s called a blastula
What happens in week 2 of prenatal development?
Gastrulation = formation of 3 germ layers
What are the 3 germ layers and what is their future development?
- Ectoderm = skin, hair, nervous system
- Mesoderm = muscles, bones
- Endoderm = organs
What is a morula?
A ball of 16 cells with cell differentiation in the zygote stage
What happens in week 3 of prenatal development?
Neurulation –> formation neural plate –> neural groove –> neural tube
This is the formation of the CNS, where the neural tube is the spinal cord
Which germ layer is important in neurulation?
Ectoderm
When is the first primitive brain developed? Of which parts does it consist?
After 4 weeks, consists of midbrain and forebrain
What happens at 7-8 weeks?
Start of reflexes in spinal cord
What are 2 possible consequences if the neural tube fails to close?
- Open skull/anencephaly
- Open back/spina bifida
What is the forebrain, midbrain and hindbrain in embryo development?
Forebrain: cerebrum + diencephalon
Midbrain: midbrain (brainstem)
Hindbrain: pons + medulla
What is the timeline of cerebral development?
- 9 weeks: start development
- 3 months: mainly reflexive spinal responses
- 4 months: cells cerebral hemispheres migrate
- 6 months: cortex folds –> sulci/gyri
- Brain grows and develops 6 layers
- > 6months: matured cerebral cortex with enough cells, volume has to increase
How does the fetal brain grow after 6 months?
Mainly through synaptogenesis and myelination
What’s the difference between active and quiet sleep in fetuses? How does it develop from 34-38 weeks?
Active = movement, irregular heartbeat, responsive
Quiet = motionless, steady heartbeat
34 weeks: patterns of rest and activity
38 weeks: less active sleep because of brain maturing
Why is active sleep in fetal development important? State 2 reasons
- Stimulation neural networks for maturation nervous system
- Breathing movements important for lung development
Why do sulci and gyri develop? From which week does this start to happen?
Because the volume of our brain is too large, it folds
From 6 months onward
When is the biggest chance of miscarriage?
0-4w: 10%
4-8w: decrease of chance on miscarriage
When is the biggest risk for neural deviations? Why?
From week 3-8, because the CNS is formed through neurulation in that time
What is the rooting reflex? What is its function?
Reflex that causes newborn babies to respond to one of their cheeks being touched by turning head in that direction
Helps to find nipple
When does the first response to touch occur in prenatal development?
8 weeks
Why are the chemosensory senses (taste/smell) pretty well developed at birth?
Fetus can smell everything in amniotic fluid from 16 weeks and tastes the mother’s blood
What is the vestibular system? Where is it located?
System for balance and spatial orientation. It’s located in the vestibular apparatus in 3 canals in inner ear
How is the vestibular system developed in utero? How does this project to behavior after birth?
System is actively stimulated by movement of the mother.
After birth, a baby will be calm when rocking and letting it sleep
What is the kangaroo method and what is the evidence that it works?
Skin-to-skin contact for premature babies
- Helps development autonomic nervous system and vestibular system
- Positive influence on circadian rhythms
What is the timeline of the prenatal development of the eyes? Name 4 time points
5 weeks: optic cup from ectoderm
2 months: formation lens, eyelids, muscles, iris
5-7 months: opening eyes
16-23 weeks: eye movements
What is the function of the visual pathway? How does it develop?
Deals with transmission + interpretation of stimuli
9 weeks: optic nerve to neural tube
15 weeks: optic chiasm complete
5 months: 6 stripes in LGN for what/where/ movement/form/color/detail pathways
What is the striate cortex?
It’s responsible for all basic visual functions. The surrounding area is for perceptual processes/interpretation
Why is the visual system not fully developed at birth?
Little visual stimulation in the uterus
Describe the development of the ear until week 24 (7 steps)
- 6 weeks: inner ear + middle ear tube
- 7 weeks: external ear + ear drum
- 8 weeks: cochlea
- 10 weeks: sensory celss cochlea + 2 bones middle ear
- 14 weeks: vestibular system works + cochlea rolls up + connection auditory nerve to cochlea
- 20 weeks: 3rd bone in middle ear + hardening of bones
- 24 weeks: cochlear function + shape outer ear
When can the fetus detect acoustic stimulation? Which types of sounds are detectable?
23-25 weeks –> mostly low sounds
What is transnatal learning? Give an example
Learning that starts in prenatal period and is continued or remembered in postnatal period
At 35 weeks fetus learns habituation and dishabituation where there first was no dishabituation
What is the most important bridge for newborns from uterus to real life?
Maternal voice provides comfort and trust
When can newborns distinguish mother’s language from a foreign language?
Within 4 days
What does ‘perinatal’ mean?
The period just before and after birth
What are 2 characteristics of a critical period?
- Period for optimal specific development
- System is vulnerable for lesions
What are 5 types of risk factors?
- Age of parents
- Nutrition, drugs, alcohol, smoking
- Stress
- Mental disorders + medication
- Infections
What is the relation of the age of the father to prenatal development?
The older, the more risk for neurodevelopmental / psychiatric disorders and impairments in social function
Give an example of a cultural disease
Sickle cell anemia in afro-americans occurs much more often than in other ethnic groups
What are autosomal genetic disorders?
Disorders that result from mutation in a gene in one of the non-sex chromosomes
In which 5 cases (or combination of it) is prenatal supervision recommended?
- Prenatal care avoiders
- Pregnant women without permanent residence
- Pregnant women with psychiatric disorder / aggression
- Addiction problems
- Previous child that was supervised/removed from home
What is FAS and when does it occur?
Fetal alcohol syndrome
- Facial anomalies, growth delay, heart defects, mental disabilities
- 6% of children of alcoholic mothers
Severity depends on drinking behavior, genetic predisposition and mother’s nutrition
What are 6 risks of smoking in prenatal development?
- Preterm birth
- Fertility problems
- Heart defects
- Delay growth
- Increased risk miscarriage
- Placenta problems
What is ETS? How can this influence prenatal development?
ETS = environmental tobacco smoke
- Low birthweight, asthma, ADHD
What is an important confound in research on drugs and prenatal development?
Is it the drugs that have an impact on child development or is it genetic predisposition or is it mother’s behavior
What is a POP poli?
Centre for pregnant women with mental problems
With which health risks are low and high birthweight associated?
Low: cardiovascular disease
High: breast cancer
What were some consequences of the Dutch hunger winter for fetal development?
These children had an increased risk on schizophrenia, mood disorder and antisocial disorder
What are 2 risks of extreme maternal stress? What are benefits of some maternal stress?
- Low birth weight
- Prematurity
Some maternal stress:
- more mature information processing
- greater motor and mental maturity at age 2
What results did Kagan find in his research on heart rate during prenatal period?
Low heart rate during prenatal period predicts lower levels of crying at 4 months
What are consequences of infection with Zika-virus for fetuses?
Microcephaly: small skull with limited brain growth and organ defects
What is an ultradian rhythm? Give an example
Rhythms/cycles that repeat in less than a 24h period
Example: feeding
