1. The Reproductive System

2. Crash Course in Reproduction

3. Defining Sexual Reproduction
1. A sex organ produces sex cells
2. A sperm combines with a egg
3. A zygote is produced and develops into an embryo
4. The embryo develops through mitosis and cell division into a mature offspring

4. Sexual Reproduction

5. Types of Sexual Reproduction

6. Conjugation Some bacteria don’t have a nucleus.
Conjugation is when two bacteria join together at their membrane.
they can share small pieces of DNA

7. Separate Sexes Sex cells are made by plants and animals
Gametes are sperm and egg cells.
Gametes have half as many chromosomes as a body cell.
Fertilization is when gametes meet to start forming a new organism

8. Internal vs. External Fertilization
Internal Fertilization is when gametes meet inside of a female
(ex. Primates, Elephants)

9. Internal vs. External Fertilization
External Fertilization is when two gametes meet outside of an adult
(ex. Fish such as salmon)

10. Hermaphrodites
individuals who create both male and female sex cells within the same body.

11. Hermaphrodites
Slow or motionless organisms succeed as hermaphrodites (they can be less picky about mates that way).
Flat worms can exchange sperm and eggs with one another.

12. Male Anatomy

13. Testes Produces the sperm Contained inside the scrotum
Hangs outside of the body to decrease the temperature (approx 3 degrees)
Optimum sperm production at lower temperatures

14. Prostate Gland
The source of seminal fluid

15. Sperm: the swimmers One cell
Head – Contains DNA that enters into the egg at fertilization
Mitochondria – Gives energy to allow the flagellum to move
Flagellum/tail – Propulsion
Live for up to 5 days inside of
the female

16. Epididymus: storage Stores the mature sperm
If sperm not used, white blood cells scavenge and devour old sperm

17. Vasectomy
Two small incisions are made on either side of the scrotum through which the vas deferens can be cut and tied/sealed to ensure it does not reattach

19. The Voyage of Sperm

20. Ejaculation The release of semen from an erect penis
Sperm is forced through the vas deferens by involuntary contractions
Passes by the prostate and seminal vesicles
Prostate and Seminal Vesicles: provide fluid that activate the sperm (sugars that give the sperm nourishment)

21. Ejaculation
The semen and sperm are ejected out of the penis through the urethra
sperm cells are released

22. Female Anatomy

23. Egg Preparation: the other side
All eggs begin in the ovary
Eggs begin as a follicle (it is the eggs plus several other cells that give the egg nourishment)
The human ovary contains immature follicles
Once mature the ovary releases the egg into the oviduct (fallopian tubes) to wait for the sperm

24. The Ovary: Ovulation

25. Swimming in unsafe waters
Post-ejaculation
The sperm are inserted into the vagina and swim into the uterus
The vagina is a harsh place, 25% of sperm die upon ejaculation

26. The long journey Sperm then have to choose between fallopian tubes
½ go the wrong way…

27. Fertilization
The remaining sperm, then need to dig through the layers of the egg to fertilize it
Only one sperm gets through, then the egg’s membrane becomes impermeable

28. Fertilization
Once the sperm has joined with the egg, the zygote moves down the fallopian tube into the uterus and attaches to the endometrium

29. Fertilization Video http://www.youtube.com/watch?v=_5OvgQW6FG4
- min.15-20

30. Ectopic Pregnancy

31. Menstruation
When a woman menstruates, she sheds the lining of her uterus (endometrium) because she is not pregnant. This shedding of the endometrium is the bleeding that women experience roughly every 28 days.

32. Menstrual Cycle – Why do women menstruate?
Average menstrual cycle is 28 days
Menstruation (or the bleeding) lasts about 3-7 days.

33. Menstrual Cycle – Why do women menstruate?
Each month, the uterus prepares for a fertilized egg to embed in its lining
The lining has a rich blood supply to potentially support a embryo
If a fertilized egg does not implant (ie: the woman does not get pregnant), the lining is shed (menstruation) and a new cycle begins
This whole cycle is regulated by several hormones

35. Hormones

37. Birth Control Pills

38. Birth Control Pills
The pill has many formulations, but most contain synthetic estrogens and progestins, and some contain only progestin.
keep the levels of circulating estrogens and progestins HIGH
avoid that big drop at day 11
big drop prevents LH and FSH from increasing, which prevents ovulation

39. Birth Control Pills So why do you still menstruate on the ‘pill’?
the last week you are only taking placebo pills…and so estrogen and progestrone levels drop off, causing menstruation.