Lecture 3a: Pregnancy and Physiological Changes Flashcards
When are follicles matured?
During ovulation
What is the release of a mature follicle (and the egg within it) triggered by?
a surge in luteinizing hormone (LH)
Where does a mature egg go once released?
Once released from ovary the egg goes into the fallopian tube
How many sperm make it to the egg cell (if intercourse at proper timing occurs)?
Only a few hundred of up to 300 million make it to the egg cell
What is a zygote?
When a sperm successfully penetrates the egg - genetically complete
What happens after a zygote is successfully made?
undergoes series of cell divisions called cleavage - divisions increase the number of cells not overall size of embryo (mitosis)
What 3 phases of cleavage does the zygote undergo?
2 cell stage, 4 cell stage, 8 cell stage
What does a zygote become once divided?
After several divisions, it is composed of about 16 cells. At this stage, it is referred to as a morula - 16 cell stage
When Does the Zygote Become an Embryo?
After 10 days
When is the morula formed?
Around 4 days after fertilization
What happens to the morula?
continues to divide, fluid begins to accumulate between the cells, marking the transition into a blastocyst
When does the blastocyst form?
Around 6 days after fertilization
What happens to the blastocyst cells?
More than 100 cells. Fills with fluid and cells seperate into 2 groups
What is the structure of a blastocyst?
Trophoblast = outer layer
Embryoblast (ICM) = cluster of cells inside the blastocyst
What happens to trophoblast cells?
develop into the placenta
What happens to the embryoblast cells?
develop into the fetus
When does implantation occur?
Around 10 days after fertilization
When does pregnancy begin?
At conception
What is EDD?
Estimated Date of Delivery
When is EDD?
Typically counted from first day of last menstrual period (LMP); 40 weeks from LMP or 38 weeks after conception
When is the first trimester?
Conception to 12th week
When is the second trimester?
13th to 28th week
When is the 3rd trimester?
28th to birth
What is considered pre-term? (premature)
less than 37 weeks
What is considered term?
37-42 weeks