Chapter 4 - Prenatal Devel. and Birth Flashcards
(136 cards)
what are the 3 stages of prenatal development
period of zygote, embryo, and fetus
how long does the period of the zygote begin and last
begins with fertilization and lasts about 2 weeks (when fertilized egg implants itself in wall of uterus)
what is a fertilized egg called
zygote
what is the period of zygote mainly characterized by
rapid growth through cell division
in zygote period, how often does cell division occur
every 12 hours
by the end of the first week, what happens to the zygote and what is next
recheas the uterus
-implantation
what is implantation, how long does it take and what does it trigger
burrowing of zygote into uterine wall and connects to the mothers blood vessel
-takes about a week
-triggers hormonal changes that prevent menstruation
what is the germ disc of a zygote
small cluster of cells near center that eventually develops into the baby
what is the layer of cells of the zygote closest to the uterus called
placenta
what marks the end of the period of the zygote
implantation and differentiation of cells
when does the period of the embryo begin and end
once zygote completely embeds istelf in uterine wall
-begins around 3rd week after conception and lasts until end of 8th week
what is the period of the embryo mainly characterized by
development of body structures and internal organ
what are the 3 layers that form in the embryo at the beginning of th eperiod and what will they become
-outer: ectoderm - hair, outer layer of skin and NS
-middle: mesoderm - msucles, bones, and circulatory system
-inner: endoderm - digestive system and lungs
in what period of prenatal development can you begin to see eyes, jaw, arm and legs
period of the embryo
where does the embryo rest inside the mother
amniotic sac
what is the purpose of amniotic fluid
to cushion embryo and maintain constant temperature
what allows nutrients, oxygen, vitamins, and waste products to be exchanged between mother and embryo
the villi from the umbilical blood vessels that lie close to the mothers blood vessel
what are the 2 important principles of grwoth in the period of the embryo
-cephalocaudal: growth from the top and extending downward
-proximodistal: growth from the center and extending outward
what is the longest phase of prenatal developmetn and how long does it last
period of the fetus
-from the ninth week after conception until birth
what is the period of the fetus mainly characterized by
child becomes much larger and its bodily systems begin to work
at what period of prenatal development can the mother start to feel the baby
period of the fetus
at 4 weeks after conception, during the fetus period, what main thing happens
-flat set of cells curls to form a tube
-at one end it swells to form brain
-rest forms spinal cord
describe the brain at the beginning of the fetus period
-has distinct structures and begun to regulate body functinoing
-all regions of brain grow especially cerebral cortex
what is the cerebral cortex
folded surface of the brain that regulates many important human behaviours