prenatal behaviour Flashcards
how are gametes produced?
through meiosis
what happens in the union of gametes? (2)
each gamete has half the genetic material of all other normal cells (due to meiosis process)
when they come together the zygote has a complete set of human genetic material
what are the 3 stages of prenatal development?
germinal, embryonic, fetal phases
what happens in the germinal stage of prenatal development? (4)
- conception-2 weeks
- zygote implanted in uterine wall
- rapid cell division through mitosis - zygote doubles its number of cells roughly twice a day
- development of twins in this stage
how do twins develop during the germinal stage?
- Mz originate from splitting in half of the inner cell mass, resulting in the developing of genetically identical individuals
- Dz originate when two eggs are released into the fallopian tube at the same time and are fertilised by different sperm
what happens in the embroyonic stage of prenatal development? (2)
- 3rd-8th weeks
- develop of organs and systems through processes of cell division, cell migration, cell differentiation, cell death
embroyonic stage: what are the 4 processes of development used in this stage
- Cell division – results in the proliferation of cells
- Cell migration – movement of cells from point of origin to other locations in embryo
- Cell differentiation – transformation of stem cells into specialised
- Cell death – apoptosis
embroyonic stage: how does the embryo’s support system develop during this stage? (2)
- neural tube – formed from top layer of differentiated cells in the embryo – eventually becomes brain and spinal cord
- support system - placenta (allows exchange of materials between bloostream of foetus and mother) and umbilical cord (tube containing blood vessels that travel from the placenta and foetus)
what happens during the fetal stage of prental development? (4)
- 9th week – birth
- Continued development of physical features and rapid growth of body
- Receives antibodies from mother in last month of pregnancy
- Increasing level of behaviour, sensory experience and learning
fetal stage: what are the 2 main methods the foetus is protected during this stage?
- Placental membrane – barrier against infectious agents
- Amniotic sac – membrane filled with fluid that gives a protective buffer for foetus and helps regulate temperature
fetal behaviour: how does fetal behaviour develop during this stage? (5)
- Spontaneous movement from about 5 weeks and hiccups often occur at 7 weeks (practice of burping reflex)
- around 18-19 weeks (slightly before fetal stage) most arm movements are hand to mouth
- By 12 weeks – most movements will match the movements that will occur after birth (postnatal continuity):
- Swallowing amniotic fluid promotes development of palate and maturation of digestive system
- Movement of chest wall and pulling in and expelling small amount of amniotic fluid aiding respiratory system becoming functional
fetal behaviour: how does the fetal rest-activity cycle develop during this stage? (3)
- Becomes more stable during second half of pregnancy
- Circadian rhythms apparent
- Near end of pregnancy the foetus’ sleep and wake states are similar to those of the newborn
fetal behaviour: how does the fetal sensation and perception develop during this stage? (4)
- Sensory structures present relatively early in prenatal development and play a vital role in fetal development and learning
- Foetus experiences tactile simulation and tastes and smells the amniotic fluid
- Responds to sound around 6th months of gestation
- Foetal visual experience - recent evidence shows preference for “faces” in the fetus (Reid et al., 2017) without the need for postnatal exposure
what has research demonstrated about foetal learning/habituation? (3)
- Around 30-32 weeks of gestation, foetus decreases responses to repeated stimuli – habituation
- Newborn infants been shown to recognise rhymes and stories before birth
- Newborns also prefer smells, tastes, and sound patterns that are familiar because of prenatal exposure
what are teratogens?
environmental agents that have the potential to cause harm during prenatal development
when are teratogens most dangerous to a foetus?
many agents only cause damage if exposure occurs during a sensitive period in development (i.e if the teratogen attacks the area which is currently under development)
what 2 key factors influence how dangerous a teratogen is to a foetus?
- Amount and length of exposure to the teratogen is also key – most terogens show a dose-response relation meaning increased exposure = likely bigger issues
- Individual difference also effect influence of teratogens
why is it so difficult to identify their teratogents/their effects?
may be a combination of teratogens impacting the mother at once (e.g polluted environment, poorer diet etc) and sleeper effects (impact of agents not apparent for many years) meaning they’re harder to recognise
