Download Unit 11 p3

NOTES – UNIT 11 part 3: Fertilization and Birth:
Recall that the corpus luteum is secreting progesterone & estrogen. High levels of progesterone & estrogen
inhibit secretion of FSH while the egg is traveling through oviduct (no new follicles can develop).
– IF embryo does NOT implant in uterine lining by the end of this phase, a new menstrual flow phase
begins
• Disintegration of the Corpus Luteum reduces progesterone & estrogen which reduces blood
flow to the endometrium  the endometrium breaks down & passes out of the uterus
– IF embryo is present, embryo secretes HCG (hormone) which maintains the Corpus Luteum.
Therefore, estrogen & progesterone continue to be secreted and the endometrium is maintained
•
And estrogen & progesterone inhibit any more follicles while fetus develops
PREGNANCY TEST: looking for HCG in urine
FERTILIZATION & IMPLANTATION
● most fertilization occurs in the ____________________________
● cell division (mitosis) begins approx. 24 hours after conception
● after 3 days, embryo contains approx. 16 cells
● embryo reaches uterus approx. 7 days after fertilization & contains
approx. 100 cells (_______________________)
● implantation of blastocyst occurs within next 5 days
● for the first 2-4 weeks, embryo obtains nutrients directly from endometrium (____________________)
● in 2nd trimester, _____________________________________________________ to maintain pregnancy
-HCG maintained pregnancy early on by causing estrogen & progesterone secretion by Corpus
Luteum
HUMAN GESTATION: 3 trimesters
● 1st trimester: ________________________________________
–
At 8 weeks, embryo is called a fetus
–
5 cm long by the end of trimester
● 2nd trimester: hormone levels stabilize & placenta takes over progesterone production
–
Uterus & fetus growing!
–
Can feel __________________________________________
● 3 trimester: as fetus grows, activity decreases
rd
–
Mother’s abdominal ____________________________________________________
–
Complex interplay of local regulators (prostaglandins) & hormones (estrogen & oxytocin)
induces labor
BIRTH:
● _______________________________ levels during the last
weeks of pregnancy trigger formation of
___________________________________ in uterus
● Oxytocin secreted by fetus & posterior pituitary of mother stimulate
smooth muscles of uterus to contract
● Oxytocin stimulates _________________________ secretion by
placenta which __________________________________________
of uterus (positive feedback)
● Decreased levels of progesterone after birth remove inhibition from anterior pituitary which allows for
prolactin secretion
AFTER BIRTH:
● PROLACTIN stimulates milk production after 2-3 days
● Oxytocin controls ________________________________ from MAMMARY GLANDS (positive feedback)
Ectopic Pregnancy:
Symptoms:
•
Light vaginal bleeding
•
Nausea and vomiting
•
Lower abdominal pain
•
Sharp abdominal cramps
•
Pain on one side of your body
•
Dizziness or weakness
•
Pain in your shoulder, neck, or rectum
•
Will have a positive pregnancy test