pregnancy and embryonic development Flashcards
what occurs within the first five weeks of embryonic development?
- The inner cell mass forms three primary cell layers-endoderm, ectoderm and mesoderm
- The amniotic membrane forms
- Brain forms
- Liver is prominent
- Heart begins to form/beat
- limb buds begin to appear
what foetal development has occured by 3 months?
Blood cells formed in bone marrow
what foetal development has occured by 4 months?
Arms and hands fully shaped
what foetal development has occured by 5 months?
fine hairs covers body
what foetal development has occured by 6 months?
tooth buds evident
what foetal development has occured by 7 months?
All systems functional except respiratory system
what foetal development has occured by 8 months?
Accumulation of fat beneath the skin
what foetal development has occured by 9 months?
Eyes open + nose well formed
what is Amniotic fluid
- protects the embryo against physical injury by acting as a shock absorber
- maintain a constant temperature
how does blood flow from the Foetus to placenta?
umbilical arteries
how does blood flow from the placenta to fetus?
a single umbilical vein
blood flow from Mother to placenta?
diffusion
blood flow from placenta to mother?
diffusion
what is gestation?
time the feotus is in the uterus
lasts for 280 days
what is the first stage of labour?
dilation of the cervix
- Strong contractions get more frequent
- Cervix dilates
- Lasts about 8 to 9 hours
what is the second stage of labour?
stage of expulsion
- Lasts from 20 mins to 2 hours
- Baby born head first,
what is the third stage of birth
afterbirth
- Placenta detaches from the uterus and is delivered
how is a zygote formed and implanted?
- forms in the fallopian tube when sperm fertilizes the egg
- Undergoes mitosis
- Becomes a morula
= Becomes a blastocyst - Enters the uterus where for 2-3 days
- Forms an inner cell mass
- Attach to uterine wall to gain nourishment
- Inner cell mass forms three embryonic layers
what is formen ovale?
Hole in the heart between left and right atrium
- Closes at birth
- Allows blood to bypass the lungs
what is Patent foramen ovale (PFO)?
incomplete closure of the hole between to atria in newborns
what are the complecation of what is Patent foramen ovale (PFO)?
- shortness of breath
- heart palpitations
- bluish skin of baby
how is foetal blood stream kept separate from mothers?
- chorionic villi are surrounded by pools of mother’s blood and layers of cells separate the two blood supplies
what happens to foetal circulation after birth?
- Foramen ovale closes
- Extenstion of the umbilical vein closes at birth
- Ductus arteriosus closes
- Blood flow through ductus venosus decreases
what is Ductus venosus?
the foetal blood vessel that enables blood to bypass the liver
what is Ductus arteriosus?
the foetal blood vessel that enables blood in the pulmonary artery to bypass the lungs and flow directly into the aorta-closes
why does blood bypass the foetus lungs?
foetus’ lungs are fragile and can be damaged easily
what is a teratogen?
a substance that can cause mutations/physical defects in the embryo/foetus- can cause physical damage to the unborn child
how does alcohol affect foetal development?
- Teratogen
- Foetal Alcohol Syndrome (FAS)
- Undernourishment of foetus
- Malformations of foetus
how does smoking affect foetal development?
- Changes to baby’s brain and lungs
- Reduced oxygen supply
- Retarded growth and development
how does diet affect foetal development?
- Lack of folic acid can lead to spina bifida
- Lack of calcium can lead to bone deformities
- Listeriosis caused by eating contaminated food can lead to miscarriages
