2 prenatal development Flashcards
Who observed the stages of prenatal development in chicks?
Aristotle
Where does fertilisation take place?
Fallopian tubes
Who lives longer boys or girls?
More boys at conception than girls (120/50:100)
only 106:100 at birth
gets closer over life until women take over
Boys are more vulnerable to miscarriage and illnesses/learning disabilities than women
When is the germinal phase?
Conception to 2 weeks
-lasts until zygote becomes implanted into uterus and rapid cell division takes place
When is the fetal phase?
9th week till birth
What happens during fetal phase?
- continued growth of physical structures
- rapid growth of body
- increasing levels of behaviour
- sensory experiences
- learning
- the baby receives antibodies from the mother across the placenta
When is the embryonic phase?
3-8 weeks
What happens during the embryonic phase?
- Major development in all systems and organs
- cell differentiation
- apoptosis
- cell migration
- cell division
- hormones involved
How are monozygotic twins formed?
through the splitting of the inner cell mass
What happens after implantation?
embryonic stage:
the inner cell mass becomes the embryo and the surrounding cells form the support network (placenta and umbilical chord).
A U-shaped groove forms from the top layer of undifferentiated cells which later becomes the spinal cord and brain
How is the foetus protected?
- placental barrier protects the foetus from some infectious agents
- amniotic sac acts as a buffer
- amniotic fluid helps to regulate temperature
Behaviour in the foetal stage:
-At 5 weeks hiccups
-7 weeks movement begins though they start out uncoordinated and jerky
-18 weeks most arm movements are hand to mouth
By 12 weeks most behaviours that will be present at birth are present such as:
-swallowing (small amounts of amniotic fluid to aid with maturation of palette and the digestive tract
-breathing - lungs are pulled in and out to move small amounts of amniotic fluid through to aid development of lungs
-bladder and kidneys - small amniotic wee’s
When do sensory structures develop in the foetus?
relatively early
When do they start responding to sound?
At least 6 months
At what age do foetuses habituate and what to?
- 32 weeks
- can recognise stories and rhymes read to them prenatally
- sound
- taste
- smell
- at 9 months can already differentiate between sounds (babi and biba)
