1. Human Reproductive System
Section 8.5 in Biology 12 textbook

2. Sexual Reproduction Cons: High energy cost Takes a long time
Requires 2 individuals of the same species
Can be difficult to find a mate!
Exchange of body fluids – risk of transmitting bacteria & viruses
So… why do we do it?

3. Sexual Reproduction Pros:
Offspring are genetically unique – more likely to survive
Genes can be combined in many different ways
Humans seem to like it…

4. Basic process:
Requires 2 gametes, one from the male, one from the female
Produced during meiosis
Sperm & ovum (egg)
Production of a new individual: sperm fuses with ovum
Fertilization: nucleus of the sperm passes into the egg & the 2 nuclei fuse

6. 2 nuclei: haploid + haploid = diploid
Cell divides by mitosis  zygote  embryo fetus

8. In order for sperm to meet ovum, mating has to take place
Mammals – sperm from the male is injected into the female
Sensory stimulus produces a reflex which results in the ejaculation of semen (sperm + fluids) into the vagina

9. Male Reproductive System

10. Male Reproductive System
Vas deferens
Seminal vesicle
Urethra
Penis
Prostate Gland
Epididymis
Testis
Cowper’s Gland
Seminiferous Tubules: not pictured, inside testes

11. Male Sex Hormones (Androgens)
Testosterone (& androsterone – less of this)
Produced in the testes
Stimulates spermatogenesis
Responsible for secondary male sex characteristics at puberty
Maturation of testes & penis
Male sex drive
Facial & body hair
Growth of the larynx (Adam’s Apple) – deep voice
Strengthening of muscles
Increased oil production (causes acne)

12. Negative Feedback Control
Production of testosterone & sperm controlled by hypothalamus & pituitary
Beginning at puberty (12~14 years old)
Hormones involved:
Gonadotropin-releasing hormone (GnRH)
From the hypothalamus – stimulates pituitary
Follicle-stimulating hormone (FSH)
From the pituitary gland – stimulates sperm production
Luteinizing hormone (LH)
From the pituitary – stimulates testosterone production

14. Female Reproductive System

15. Female Reproductive System
Fallopian Tube
Ovary
Fimbria
Uterus
Cervix
Vagina

16. Ovaries Contain connective tissue & follicles (small groups of cells)
Follicles are either: primary oocytes (undergo meiosis)
OR: granulosa cells (provide nutrients for oocyte)
Under constant decline (review – from meiosis ppt)

17. Ovulation At the end of meiosis I – secondary oocyte
Bursts through ovary wall & is released into the fallopian tube (oviduct)
Swept along by fimbria
Opening becomes a yellow mass of cells called the corpus luteum
Secretes hormones in the event of pregnancy
Meiosis II happens in the oviduct
Polar bodies deteriorate

19. Menstrual Cycle ~28 days in length 4 phases Flow phase
Follicular phase
Ovulatory phase
Luteal phase

20. Flow Phase Shedding of the endometrium Known as “menstruation”
Externally visible
Used to mark the beginning of the cycle
~5 days in length

21. Follicular Phase Development of follicles in the ovary
Ovaries secrete estrogen
Estrogen levels increase throughout phase
Day 6 – 13
~8 days in length

22. Ovulatory phase Ovulation happens
Short – characterized by the release of the egg from the ovary
Day 14

23. Luteal Phase Development of the corpus luteum
Estrogen levels drop during ovulation
Corpus luteum restores levels
Releases estrogen & progesterone
Progesterone – builds up the endometrium
Lining of the uterus (prepare for pregnancy)
Inhibits additional ovulation
Prevents uterine contractions
Days 15-28
~14 days in length

24. If no fertilization… Estrogen & progesterone levels drop
Uterus contracts
Endometrium pulls away from wall of the uterus
Shed from the body
Cycle starts again

26. Negative Feedback Control
Production of estrogen & progesterone controlled by hypothalamus & pituitary
Begins at puberty
GnRH from hypothalamus stimulates pituitary
During follicular phase: FSH is released & stimulates development of follicles
Follicles secrete estrogen which builds the endometrium
Increased release of estrogen causes the pituitary to stop releasing FSH

27. Negative Feedback Control
Increase in estrogen causes an increase in release of LH (+ feedback)
Stimulates ovulation
Corpus luteum forms
Secretes estrogen & progesterone
Inhibit the release of FSH & LH
Corpus luteum deteriorates, stops producing estrogen & progesterone

29. Homework Questions
Page 399 #1-11
Lab exercise 8.5.1, page