prenatal development Flashcards
recapitulation theory
embryo goes through whole evolution of the human species before getting to current human form
3 stages of foetal development
1 geminal period (conception to implantation)
- the period of the embryo (implantation to 2 months)
- the period of the fetous (2 months to birth)
germinal period
4 day safter conception - divides
5th day - earliest physical differentiation occurs
embryological vs foetal
embryo = tissue differentiation
foetal = growth
at 4months
now psychological bc exhibiting behaviour
touch
hearing
movement
8 months
responds to movement, tactile stimuli and temperature changes
aneuploidy
fewer or more than normal no. of chromosomes
teratogens
substances that cause birth defects
effect organ systems differently
e.g. thalidomide and alcohol
Descaper and Spence
baby’s showed preference for familiar stories
endothermy
mammals survived nuclear winter because of this
warm blooded
can maintain body temperature
sensory capability of newborns
touch
balance
smell
taste
hearing - fragile at birth - lower frequencies
visions improves to 20/20 at about 6 months
3 types of reflexes
Clinging - Palmar, plantar grasp and Moro
Nursing - rooting, sucking
Locomotion - crawling, stepping
related to evolution - e.g. grasping in trees
vestigial
partially or wholly lost original function
anencephaly
‘without brain’
brain has not developed properly - still sometimes exhibit reflexes so reflexes must be lower brains stem activity
brain growth
400g in to 1300g
most brain growth is not inc neurons but increase in cells that support neurons ‘glia cells’
glia cells
- Provide structural support
- Maintenance
- Insulate neuronal axons with myelin
myelination
formation of fatty sheath around axons - speeds up transmission
CNS = oligodendrocytes lay down myelin sheaths, PNS = Schwann cells
CNS vs PNS cells that lay down myelin sheaths
CNS = oligodendrocytes
PNS = Schwann cells
synaptogenesis
formation of new connections between neurons
peaks at certain points of development
usually growth of existing neurons rather than generation of new ones
critical period
clear beginning and end where a certain thing must happen for development to occur
sensitive
period not as strictly defined, development LESS likely
Hubel and Weisal
sutured left eye of cats
allowed to develop
unsutured
close to 100% only responded to input in right eye
not predetermined by genetics to serve a function
could not reverse effect - critical window
binocular
cells activated from input from both eyes
(most were like this)
monocular
cells activated from either left or right eye