Female Reproductive System

Female Anatomy

Female Reproductive System• Uterus (AKA: womb):

– protects zygote/developing embryo

• Ovaries:– Inside; found on each side

of uterus

Female Reproductive System• Uterus (AKA: womb):

– protects zygote/developing embryo

• Ovaries:– Inside; found on each side

of uterus – Produces Estrogen

1) develop female sexual characteristics

2) develop eggs 3) prepare uterus for

pregnancy

FSHLH

Estrogen

• Defined: Production of the egg cell (ovum)– In female ovaries

• During meiosis I: Cytoplasm distributed unequally

• After meiosis II:– 1 cell matures– 3 “Polar Bodies”

dissolve– Each egg has 23

chromosomes each

Meiosis 1

Meiosis 2

Oogenesis

oocyte

*Meiosis II isn’t complete until fertilization occurs!

C.L.

E Uterus

Ovary

What happens to the egg?

– Process controlled by hormones• Estrogen, Progesterone, LH, FSH

– Eggs are “housed” in follicles1. Egg matures2. Follicle ruptures, egg is released

– OVULATION3. Egg exits ovary fallopian tube uterus

– 5-7 days– Fertilization usually in

fallopian tube4. Ruptured follicle becomes

corpus luteum – Releases hormones for

zygote if egg is fertilized

Ovulation

Fertilized vs. UnfertilizedIf fertilized:• Zygote begins to divide as it

travels to uterus• Implants into uterus• Twins:

– Identical twins = same egg– Fraternal twins = 2 separate

eggs

If unfertilized:• Egg leaves uterus

– menstruation

Menstrual Cycle• Average = 28 days• three phases:

1. flow phase: • 1st 5-7 days of cycle• “tear down”

– Endometrium (lining of the uterus) sheds

Menstrual Cycle2. follicular phase:

• “rebuild” • ovulation occurs (~ day 14)

– Temperature spikes a little– Most fertile next few days!

» Able to get pregnant!

Menstrual Cycle3. luteal phase:

– Extra blood/nutrients for potential new baby – Corpus luteum forms

• Releases hormones if egg is fertilized

The menstrual cycle stops at menopause. – Age = mid 40’s- 50’s– decline in hormone levels

make cycles irregular– eventually, cycle stops

altogether

Menopause

Review1. Which hormone is primarily responsible for developing eggs?2. Which cellular process produces eggs?3. How many chromosomes are found in each egg?4. Explain the function of the following parts : ovary, fallopian tube, uterus.5. Summarize the 3 phases of the menstrual cycle. What is the main

function in each phase?6. Define ovulation. In which phase of the menstrual cycle does ovulation

occur?7. What does estrogen do? In what ways are the effects of testosterone on

males and estrogen on females similar?8. Describe how an egg is fertilized.9. Explain the difference between identical and fraternal twins.10. If twins are born, and one’s a girl and the other is a boy, are they

identical or fraternal? Explain.