1. Female Reproductive System

2. Basic Anatomy Ovary (gonads)
Follicles containing oocytes (immature egg cells)
Corpus luteum
Fallopian Tubes
Pathway from ovary to uterus – site of ideal fertilization
Uterus
Destination for fertilized egg to implant and be sustained
Vagina
Entry for sperm
Exit for baby

3. Basic Anatomy – The Brain
Pituitary Gland:
Releases Hormones
Hypothalamus:
Tests blood levels for various hormones and decides what should come next – sends signals to pituitary

4. Basic Hormones FSH - Follicle Stimulating Hormone
Secreted by the pituitary gland (both male and female)
Stimulates the follicle to form and grow (effect in female)
LH - Lutenizing Hormone
Causes ovulation (release of a mature egg) and causes the corpus luteum to form (effect in female)
GnRH - Gonadotropin Releasing Hormone
Secreted by the hypothalamus (at the base of the brain next to the pituitary gland) (both male and female)
Causes the pituitary gland to increase production of FSH (both male and female)

5. Cow’s Head

6. Follicle Stage Days 5-13 Increased FSH levels cause:
Follicle to enlarge
Follicle to produce more estrogen

7. Follicle Stage (cont) Increased estrogen levels cause
endometrium to thicken
hypothalamus (brain) to tell pituitary (also brain) to release more FSH and LH

8. Ovulation Around day 12-15 Peak levels of FSH and LH cause
Follicle to rupture
Egg is released into fallopian tube (about the diameter of a human hair)
Egg has 24 hours to be fertilized or it will die

9. Luteal Stage
Days 16-29
Peak of lutenizing hormone stimulates corpus luteum (Latin for yellow body) to form from empty follicle

10. Luteal Stage (cont)
Corpus luteum secretes some estrogen and, as it grows, increasing amounts of progesterone cause:
Endometrium wall to thicken
FSH and LH drop to see if pregnancy occurs (takes 6-7 days for zygote to travel and implant)

11. Basic Hormones (cont.) Estrogen Progesterone
Secreted by the follicle and the corpus luteum
Causes the outer lining of the uterus (endometrium) to thicken
Progesterone
Secreted by the corpus luteum
HCG - Human Chorionic Gonaditropin
Secreted by the implanted embryo
Causes progesterone levels to stay high and maintain a thickened uterine wall
Levels are detected by pregnancy tests – if it is there, then there is a pregnancy (no false positive but can get a false negative)

12. Pregnancy? If pregnancy occurs:
Embryo implants and placenta starts releasing HCG so mom’s body knows it’s pregnant
Initially, mom maintains progesterone and estrogen after month 3, baby does it on its own
This keeps endometrium wall thick and
Prevents hypothalamus from secreting GnRH which prevents the pituitary from producing FSH and starting all over.
Isabella at 1 week old
James at 1 week old

13. Menstrual Phase If no implantation has occurred
Corpus luteum breaks down
Progesterone drops
Days 1-5
Endometrium breaks down and is expelled
Hypothalamus detects low progesterone and estrogen and release GnRH
Pituitary releases FSH…..

15. Summary of Events

17. What do birth control pills do?
There are several different brands but the main categories work in one of two ways:
Keep estrogen at artificially high levels – simulating levels during pregnancy.
This stops the hypothalamus and therefore the pituitary from starting the cycle over and releasing an egg
No egg = no chance for pregnancy
(1/100 chance = 99% accuracy!)
Use progestin alone or with estrogen
Progestin makes it difficult for implantation to occur and for sperm to travel to the fallopian tubes.
Note: progestin is a synthetic version of progesterone and is similar in how it works
After 21 or so days, the hormones stop (placebo or no pill) and the body prepares for the next cycle by menstruating