gestation Flashcards
embryonic period-week 1
-first eight weeks of development
-fertilization
-zygote
-morula
-blastocyst
fertlization
merging of genetic information from sperm cell and oocyte
zygote
fertilised egg divides into two cells
morula
cluster of cells by day 4
blastocyst
32 cell mass with fluid-filled cavity
embryonic period-week 2
-chorion becomes a principle part of the placenta
how does the placenta protect the embryo from the mother’s immune system
-secreting proteins to block mother’s antibodies
-producing T cells (leukocytes) to suppress mother’s immune response
embryonic period-week 3
-gastrulation
-neurulation
-angiogenesis
gastrulation
embryonic disc splits into three germ layers:
1. ectoderm
3. mesoderm
3. endoderm
ectoderm becomes…
- digestive system
- liver
- pancreas
- lungs (inner layers)
mesoderm becomes…
- circulatory system
- lungs (epithelial layers)
- skeletal system
- muscular system
ectoderm layer
- hair
- nails
- skin
- nervous system
neurulation
cellular components of the nervous system start to form (neural crest, tube and plate)
angiogenesis
the formation of blood vessels
embryonic period-week 4-8
-organogenesis
-embryonic folding
organogenesis
major organs developing
embryonic folding
embryo folds into a 3D cylinder in week 4, bone formation, major blood vessels and blood cells start to form
embryonic period-week 9-36
-tissues and organs grow and differentiate
by week 12
the placenta divides into feotal (chorion) and maternal portions
what does the placenta do?
-stores and diffuses nutrients
-excretes wastes into maternal blood
-mediates exchange of oxygen, carbon dioxide and hormones between mother and fetus
feotal circulatory system
-umbilical cord
-umbilical vein
-umbilical arteries
-shunt
umbilical cord
contains one umbilical vein and two umbilical arteries
umbilical vein
carries blood (full of nutrients and oxygen) to the fetus
umbilical arteries
carries blood (full of waste and carbon dioxide) from the fetus to the placenta
shunt
anatomical diversion to bypass immature organs, present in the heart and liver
week 12
-bone formation
-heartbeat detected
-gender determined
-brain expansion
-movement begins
-urine secreted
week 16
-meconium (faeces) accumulate in the intestines
-lower limbs strengthen
-body systems develop rapidly
week 20
-growth slows down
-brown fat forms
-movements felt by mother
-waxy coat and hair protects skin
week 24
-weight gain
-pink and wrinkled skin
-can survive now if prematurely born
week 28
-eyes open
-subcutaneous (under the skin) formed
-red bone marrow produces red cells
-lung and nervous systems can control breathing/blood temperature
-‘practise’ breathing
week 32
-smooth skin
-upside down position
-8% fat
week 36
-abdomen circumference bigger than the head
-growth slows down further
-16% body fat
prenatal diagnostic tests
-fetal ultrasonography
-amniocentesis
-abnormalities
-chronic villus sampling
-maternal alpha-fetoprotein (AFP)
fetal ultrasonography
can detect
-fetal age
-position
-confirm pregnancies (or multiple pregnancies
amniocentesis
-analyse amniotic fluid
-analyse feotal cells for genetic abnormalities
-by using a needle guided by ultrasound
chorionic villus sampling
-analyse amniotic fluid
-analyse feotal cells for genetic abnormalities
-reveal genetic abnormalities
maternal alpha-fetoprotein (AFP)
-uses a blood sample from the mother
-detects if AFP is present after 16 weeks
-indicates neural tube defect
