Fertilization and Pregnancy Flashcards
What happens during fetilization
during intercourse millions of sperm travel through the cervix and uterus to the egg in the fallopian tube, only one sperm attaches and sues with a mature ovum producing a zygote
Zygote
First cell formed after fertilization containing a complete set of DNA from both parents
Prenatal trimesters
three month periods of development
What happens to cell after fertilization
4-6 days after fetilization the zygote divides(mitosis) repeatedly to form a morula(16cells) the morula froms a blastocyst
Morula
(16 cells) a solid ball of cells
Blastocyst
A hollow ball of cells that will implant in the uterus
Implantation
The blastocyst attaches to the uterine wall(endometrium)
Cleaage
Repeated mtotic division of the zygote
Reason for embryos failing to complete cleavage or gastrulation
-Genetic mutations
-Hormonal imbalances
-Failure to implant properly in the uterus
Grastrulation
A process where the blastocyst transforms into a structure with three germ layers
What happens with fraternal twins(Dizygotic)
Two seperate eggs are released and fertilized by two different sperm
What happens with identical twins(monozygotic)
A single fertilized egg splits into two cell masses( those twins have idential DNA)
High levels of progesterone and estrogen
Maintain endometrium, prevent uterine contractions, and stop ovulation so no new eggs are released
HCG(human chorionic gonadotropic)
Produced by the placenta, keeps the corpus luteum active in the first 3 months, after 4 months placenta produces estrogen and progesterone
Gastrulation
The embryo forms three germ layers that develop into different body parts
What are the three germ layers that will develop into body parts
1.Ectoderm(the outer layer)-Nervous system, skin, hair, eyes
2.Mesoderm(the middle layer)-Muscles, bones, heart, blood vessels
3.Endoderm(inner layer)-Digestive system, lungs, liver
Neurulation
The process where the neural tubes form that tube developes into the brain and spinal cord
Folic acid
A vitamin that prevents birth defects in the brain and spine
The placenta
Formed by the fused cells of the fetus and endometrium, supplied with blood vessels to transport nuteriens and oxygen. The finger like projections(Chorionic villi) ensure the fetus has many exposed blood capillaries
Umbilical Cord
COnnects fetus to placenta formed from the allantois layer
Chorionic villi
tiny finger like projections in the placenta that allow for nutrient exchange
Allantois
An early fetal structure that later forms the umbilical cord
Major layers of blastocyst(outside embryo)
1.Chorion-outer layer
2.Amnion-inner layer
3.Allantois
4.Yolk Sac
Chorion
outer layer that produces HCG, thickens placenta and forms from the trophoblast
