1. Sex and Hormonal Control of Human Sexual Cycles

2. What is a Hormone? Long range and long lasting way for an organism to regulate signals to itself As opposed to –Electrical signals by the nervous system –Pheromones

3. Females Ovaries are where gametes are created Viable gametes: eggs Eggs are gestated inside of a follicle, which matures once every ~28 days

4. Mature Follicle

5. Female Reproductive Tract Fallopian Tube Uterus

6. Ovarian Cycle Follicular Phase (1-14) Luteal Phase (14-28)

7. Follicular Phase days 1-7 Follicle growth stimulated by FSH (follicle stimulating hormone) and LH (luteinizing hormone) released by Pituitary Growing follicle secretes estrogen, which prepares the uterus for pregnancy by telling it to increase wall lining

8. Follicular Phase days 7-14 While estrogen is on the rise due to a growing follicle, FSH and LH levels decrease The first follicle to reach maturation “wins” and…

9. Ovulation day 14 When estrogen level reaches its threshold, all stored LH and FSH is released Causes the release of an oocyte (egg cell) What remains of the follicle stays and becomes corpus luteum, continuing to churn out signals to produce female hormones(primarily progesterone) until lack of implantation is assured Remaining follicles are absorbed into body

10. Ovulation

11. Luteal Phase days 14-24 Rise in progesterone from the corpus luteum prevents the rest of the follicles from ovulating Causes uterine lining to continue thickening

12. Luteal Phase days 24-28, if oocyte not fertilized Corpus luteum dies and becomes whitish scar tissue Progesterone levels plummet Causes uterine lining to shed Without any more inhibition, FSH and LH hormone levels rise once more, beginning the cycle fresh

13. Luteal Phase, days 24-28, if oocyte is fertilized The corpus luteum is kept alive until the placenta can take over for the growing fetus Progesterone levels remain high Causes uterine lining to stay intact Keeps LH and FSH levels low, preventing further maturing of follicles The fertilized egg, once implanted in the uterine lining, will also produce hCG (human Chorionic Gonadotropin) to keep the uterine lining thick –This is the hormone pregnancy tests identify

14. Estrogen –Promotes bone lengthening –Inhibits bone reabsorption –Promotes skin hydration –Causes characteristic fat deposit growth –Raises retention of sodium and water –Raises HDL cholesterol and reduces LDL cholesterol Progesterone –Promotes urination –Increases body temperature Female hormones and their secondary effects

15. Males Testes are where gametes are produced Sperm are mature male gametes Unlike female oocytes, male sperm are churned out by the millions

16. Purpose of the Scrotum Keeps testicles ~3 0 C cooler than the rest of the body Controlled by muscles and ligaments

17. Testes Produce sperm at the rate of millions per hour - yes, millions! What does this say about how much quality is inherent in sperm?

18. Production of Sperm ~24 day period

19. Vas Deferentia Tube by which sperm travels before meeting up with a seminal vesicle and ejaculatory duct Seminal Vesicles Secretes seminal fluid 60% of semen Primarily fructose (fruit sugar) Assorted enzymes

20. Male hormones and their effects Androgens (broad group) made up primarily of… Testosterone –Enhances skeletal muscle growth –Promotes growth of facial hair –Enlarges larynx –Boosts metabolic rate –Thickens skin

21. How Does the “Pill” work? First, the hormones in the pill try to stop an ovum being released from your ovary each month. This is known as the suppression of ovulation. Research has shown that neither the progesterone- only pill nor the combined progesterone-oestrogen formulations always stop ovulation.

22. Second, all formulations of the pill cause changes to the cervical mucus that your body produces. The cervical mucus may become thicker and more difficult for sperm to fertilize an ovum.

23. Third, all formulations of the pill cause changes to the lining of the womb (properly known as the endometrium). Under the influence of the chemicals in the pill, the lining of the womb doesn’t grow to the proper thickness. Periods are lighter when one is on the pill. This is because the lining of the womb has not developed properly. But this change also means that the womb is not in the right stage of development to allow a fertilized egg to attach properly (this attachment process is known as implantation)

24. Fourth, the pill causes changes to the movement of the Fallopian tubes. This effect may reduce the possibility of the ovum being fertilized.

25. Contraception Misunderstandings