1. Menstruation or Pregnancy
Human Reproduction II
Menstruation or Pregnancy

2. S1-1-09 Describe the structure and function of the male and female reproductive systems.
S Outline human development from conception through birth.
Vocabulary & People 
Ovulation Menstruation Fertilization
Zygote Embryo Fetus

3. The “egg(s)” is also know as an oocyte(s) or an ovum (ova)
Follicle – cells surrounding the egg inside
(becomes corpus luteum)
The “egg(s)” is also know as an oocyte(s) or an ovum (ova)
Ovulation:
Release of ovum from a follicle in the ovary as a response to a hormonal signal (brain - LH).
Menstruation:
Monthly cycle of changes that occur in the ovaries and uterus - including ovulation.
Ovulation occurs around the day of cycle

4. Ovulation
Endometrium: the inside of the uterus – the part that prepares for the baby – also called endometrial lining
Menstruation

5. All hormones at low levels
Menstrual Cycle consists for four steps:
approximately 28 days before repeating
STEP
Key Hormone
DAY
Brain triggers development of a follicle
Building up endometrium
FSH
Estrogen
1 - 13
Follicle releases ova (egg) – ovulation LH
Corpus Luteum forms
Endometrium is maintained
Progesterone
No fertilization – menstruation
Endometrial lining and ova are expelled
All hormones at low levels
Notice: two hormones made by the “shell ”– estrogen and progesterone – work to prepare the uterus for a fertilized egg

6. Female Menstrual Cycle
Pituitary
gland
Brain Hormone
Levels LH
FSH
FSH 7 14 21
28 days
Notice: the shedding of the endometrium ends and begins the diagram - it’s a continuous CYCLE
Ovarian
Cycle
Regression
Sex Hormone
Levels
Estrogen
Progesterone 7 14 21
28 days
Endometrial
changes 7 14 21
28 days

7. Fetal Development

8. Egg and sperm meet in the oviduct - Fertilization.
Nuclei join to produce a single diploid cell called a zygote
Zygote implants into the endometrium and releases hormones to maintain the lining
Remember: the sex is determined by the male - X or Y sex chromosome in the sperm

9. MEIOSIS– MALES x x x x y y y y x y Female sperm Male sperm DIPLOID 2n
46 Chromosomes x y
HAPLOID 1n
Female sperm
Male sperm

10. MEIOSIS– FEMALES x x x x x x x x x x Female egg DIPLOID 2n
46 Chromosomes x x
HAPLOID 1n
Female egg

11. x x x y x x y x
Female zygote
Male zygote

12. There are 2 stages of “baby” development:

13. Once implanted – called an embryo
Embryo Stage (the first 8 weeks)
Zygote implants in endometrial lining and begins to
grow (divide) by mitosis.
Once implanted – called an embryo
Congrats! You are now officially pregnant
Cleavage: the process of mitotic divisions that change zygote into a multicellular embryo.

14. Once bone forms - called a fetus (until born)
2. Fetus Stage (after 8 weeks till birth)
Developing embryo forms bone cells around the ninth week of pregnancy.
Once bone forms - called a fetus (until born)
Placenta - exchanges waste and nutrients through umbilical cord.
Amnion – protective sac filled with fluid.

15. Pregnancy can also be divided in 3 trimesters:
1st trimester – conception to 3rd month
development of all body systems and organs
fetus is particularly sensitive to alcohol/drugs
sex can be determined
1st trimester

16. 2nd trimester – 4th to 6th months
period of rapid and continuous growth
Only brain and lungs still developing
embryo movements can be felt
2nd trimester

17. 3rd trimester – 7th to 9th (birth) month
fetus kicks, stretches and moves freely
Eyes sense light, fingerprints have formed
At end – fetus weighs 3300 grams, 35 cm long
3rd trimester

18. And then, before you know it...

19. CAN YOU ANSWER THESE QUESTIONS? S1-1-09:
What parts make up the male and female sex systems and what is the function of each part?
S1-1-10:
How does a fertilized egg turn into a baby and what determines the gender?
Vocabulary & People 
Ovulation Menstruation Fertilization
Zygote Embryo Fetus