Reproduction System

1. ReproductionSystem • Aaron, Keiah, Ryan

2. Why is reproduction important? You only live once. A population transcends finite life only be reproduction, the creation of new individuals from existing ones.

3. Asexual Vs. Sexual Reproduction • Asexual reproduction is the creation of new individuals whose genes all come from one parent without the fusion of egg and sperm. • Sexual reproduction is the creation of offspring by the fusion of haploid gametes to form a zygote (fertilized egg), which is a diploid. • By producing offspring having a variety of phenotypes, sexual reproduction may enhance the reproductive success of parents when environmental factors change relatively rapidly.

4. Asexual Reproduction Many invertebrates can reproduce asexually by fission, the separation of a parent into two or more individuals of approximately equal size, e.g. sea anemone Or budding, in which new individuals arise from outgrowths of existing ones, e.g. stony corals Another way is through fragmentation, the breaking of the body into several pieces, accompanied by regeneration, the regrowth of lost body parts, e.g. many sponges, cnidarians (jellyfish, corals)

5. Asexual Reproduction Asexual reproduction has several potential advantages such as enabling animals living in isolation to produce offspring without locating mates. It can also create numerous offspring in a short amount of time, which is ideal for colonizing a habitat rapidly. Theoretically, asexual reproduction is most advantageous in stable, favorable environments.

6. Reproductive Cycles and Patterns The periodic nature of reproduction allows animals to conserve resources and reproduce when more energy is available than is needed for maintenance and when environmental conditions favor the offspring. Reproductive cycles are controlled by a combination of hormonal and environmental cues, the latter including seasonal temperature, rainfall, day length, and lunar cycles. Asexual reproduction occurs under favorable conditions, and sexual reproduction occurs during times of environmental stress. Animals can switch between producing asexually and sexually, or just be one.

7. Parthogenesis and Hermaphroditism Parthogenesis is a process in which an egg develops without being fertilized. Male honeybees are produced parthogenetically whereas females, both sterile workers and reproductive females (queens) are developed from fertilized eggs. Parthogenetic lizards, which evolved from species that have two sexes, still require certain sexual stimuli for maximum reproductive success. Hermaphroditism is where each individual has both male and female reproductive systems. Some hermaphrodites fertilize themselves, but most mate with a member of the same species. In this case, each animal serves as both male and female, donating and receiving sperm. E.g. earthworms Sequential hermaphroditism is where an individual reverses its sex during its lifetime. E.g. Caribbean bluehead wrasse

8. Caribbean Bluehead Wrasse  (Top is male, bottom is female)  Earthworms  Parthogenic Lizards

9. The Female Reproductive system

10. The Female Reproductive System. We have to draw and label it now. • http://www.ibguides.com/images/biology/female-reproductive-system.png • 6.6.1 • IB has required the drawing of a Penis on an IB, this could be on the IB

11. Anatomy 6.6.1 Vagina-a thin-walled chamber that is the repository for sperm during intercourse and is also the birth canal Vulva- the external female genetalia including the labia majora, labia minora, Bartholin's gland, clitoris, and the vestibule Cervix- The neck of the uterus that separates the uterus and the vagina Uterus- a thick muscular organ that can expand during pregnancy to hold a 4-kg fetus we will talk about this more during the pregnancy slide. The vestibule is the area where the vaginal and urethral openings are.

12. Anatomy endometrium- the inner lining of the uterus which is filled with blood vessels Oviduct- (Fallopian Tubes) takes the egg cell out of the abdominal space and moves the egg cell down to the uterus Ovary- the female gonads in the abdominal cavity on both sides of the uterus and is attached to it by the mesentery. It releases the egg cell to the abdominal cavity for the Fallopian tube to pick up.

13. 4 Stages of Sexual Response Excitement- This is when the human body prepares for intercourse. This can include myotonia (increase in muscle tone), increased breast size, and vasocongestion (swelling caused by localized increase of blood flow and blood pressure) of the reproductive organs. The uterus elevates and the inner 2/3 of the vagina expands in response to the possibility of fertilization. This can be affected by psychological factors. Plateau- the sexual excitement before orgasm in which vasocongestion continues and muscles begin to tighten. Orgasm- it is believed that during the female orgasm, muscular spasms help move the sperm up the vaginal walls into the uterus. During the male orgasm, semen goes to the urethra by emission and expelled from the urethra by expulsion. This is the shortest phase lasting a few seconds. Resolution- This is when the reproductive system of females and males returns to its normal size and leaves the stages of sexual response. This phase can be immediate, or it can last 12 to 24 hours

14. Ovary 11.4.4 Germinal Epithelium Secondary oocyte • http://www.biog1105-1106.org/demos/105/unit8/media/ovary-schematic.jpg • We will cover this in menstruation

15. Ovary germinal epithelium- the epithelial layer covering the ovary Primary oocytes- the cells that have the potential to ovulate and become an egg cell. They are diploid cells (46 chromosomes). They begin as oogonia in the womb and stop being produced at 5-6 months. At birth, a female baby will have 1-2 million primary oocytes after they matured. By puberty a girl has 400,000 primary oocytes. primary follicle- is a primary oocyte with one layer of follicle cells or a secondary oocyte with many layers of follicular cells. Mature follicle- A mass of follicular cells surrounding the secondary follicle and follicular fluid which is mature enough to release the secondary follicle during ovulation. Secondary oocyte- after meiosis I, this is a haploid cell (23 chromosomes) that will go through meiosis II and become an ovum and a second polar body.

16. Oogenesis 11.4.5 • These are the basic steps of oogenesis: • A female fetus develops diploid oogonia (stem cells) which undergo mitosis until they make thousands of primary oocytes (diploids) stopped at prophase I of meiosis until puberty. • These cells will continue to grow and develop until they are needed • Female reaches puberty with around 400,000 primary oocytes. • Each month from that point until menopause a primary oocyte will begin meiosis I and stop at metaphase II. This causes the diploid cell to divide the cytoplasm unevenly resulting in a haploid polar body and a haploid secondary oocyte in the Graafian follicle. The polar body degenerates in order to provide a suitable amount of cytoplasm to the secondary oocyte and to reduce the number of chromosomes. • Ovulation • If the secondary oocyte is fertilized, then it will go through meiosis II, dividing the cytoplasm unevenly again resulting in a second polar body and an egg with the final chromosome copy. 6 alternate. The secondary oocyte is not fertilized, then it is discarded and the female body goes through menstruation.

17. http://1.bp.blogspot.com/-VR3wPiFAptw/TgdL3gS9EaI/AAAAAAAAA0I/yH5mo2Hq0nM/s1600/Oogenesis.jpghttp://1.bp.blogspot.com/-VR3wPiFAptw/TgdL3gS9EaI/AAAAAAAAA0I/yH5mo2Hq0nM/s1600/Oogenesis.jpg Oogenesis and follicular development

18. Egg Cell 11.4.6 http://click4biology.info/c4b/11/hum11.4.htm

19. Menstrual Hormones 6.6.2 Gonadotrophin Releasing Hormone (GnRH)- released by the hypothalamus, it directs the pituitary glands to secrete FSH and LH into the blood stream. Follicle Stimulating Hormone (FSH)- Stimulates the growth of follicles, the growth of the primary oocyte, the production of follicular fluid, and the increase in follicular cells which increases the amount of estrogen. This and the Luteinizing Hormone are produced by the pituitary gland. Luteinizing Hormone (LH)- surges day 12 (middle of the cycle) to bring ovulation and to develop the corpus luteum. Estrogen- produced by follicular cells. Produces negative feed back on the pituitary gland and stimulates thickening and increased vascularization (more blood vessels) in the endometrium. It also has positive feedback on the hypothalamus later on. This and Progesterone are produced by the ovary. Progesterone- produced by the corpus luteum, it maintains the endometrium and the secretion of a glycogen solution to nourish an embreyo. It causes negative feedback on the hypothalamus and the pituitary gland.

20. Menstrual Cycle 6.6.3. • The menstrual cycle is a process in females in which the a secondary oocyte is formed, released, and not fertilized. • Because it is unfertilized the body eventually discards it along with a thickened endometrium and blood ☹ • It is also associated with Premenstrual Syndrome, which causes many different symptoms but its cause is unknown. Scientists believe it could be associated with a sudden drop of hormones.

21. The Menstrual Cycle http://www.merckmanuals.com/media/home/figures/MMHE_22_241_03_eps.gif • The cycle has 3 phases: • Follicular Phase/ menses • Ovulation • Luteal phase

22. Menstruation On day 1, the hypothalamus releases GnRH to stimulate the pituitary gland to secrete FSH and LH. The increase of FSH stimulates the primary follicle to develop. This causes the oocyte to grow, the follicular fluid to develop, and the increase in follicular cells. The follicular cells produce lots of estrogen which causes negative feedback on the pituitary gland decreasing the production of FSH and LH. It also causes the endometrium to thicken and vascularize which increases the blood vessels. This continues into the ovulatory phase. The peak of estrogen occurs around day 13 which causes positive feedback on the hypothalamus saying the body is ready to ovulate. The hypothalamus releases GnRH increasing the FSH and especially the LH. The high LH allows for ovulation in the middle of the cycle and then the LH maintains the Corpus Luteum (the body of follicular cells that exists after ovulation). This enters the Luteal phase. The Corpus Luteum continues the production of estogen and progesterone which continues to stimulate the growth of the endometrium.

23. Menstruation Continued The increase of progesterone and estrogen causes negative feedback on the hypothalamus and the pituitary gland shutting of GnRH, FSH, and LH production. Because the LH maintained the Corpus Luteum, when LH falls the Corpus Luteum disintegrates causing a harsh drop in estrogen and progesterone around day 28. The drop in estrogen and progesterone causes the endometrium to loose its source of nourishment causing it to disintegrate and fall out and bleed during menses between day 1 and day 7. During menses the body begins the follicular phase on day 1 when the hypothalamus begins to release GnRH again

24. Menstrual Cycle

25. Menstrual Cycle videos http://www.youtube.com/watch?v=lYaZRR3G6pg http://www.youtube.com/watch?v=l4X0QWcTIvk&feature=related