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Chapter 15

Chapter 15. This is the only system that. need not function to live a full, impacting life. Reproductive System. Outline. Male Reproductive System Testes and Sperm Hormonal Regulation Female Reproductive System Genital Tract Hormonal Levels Uterine Cycle Fertilization and Pregnancy

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Chapter 15

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  1. Chapter 15 This is the only system that . . . . need not function to live a full, impacting life. Reproductive System

  2. Outline • Male Reproductive System • Testes and Sperm • Hormonal Regulation • Female Reproductive System • Genital Tract • Hormonal Levels • Uterine Cycle • Fertilization and Pregnancy • Control of Reproduction • Infertility

  3. Hormonal Regulation in Males • Hypothalamus secretes gonadotropin-releasing hormone (GnRH). • Stimulates anterior pituitary to secrete: • Follicle-stimulating hormone (FSH). • Promotes sperm production. • Luteinizing hormone (LH). • orInterstitial cell-stimulating hormone (ICSH) • Controls testosterone production. • Testosterone is essential for reproductive organs and male secondary sex characteristics . . . beard, body hair, voice change, muscle strength.

  4. Hormonal Control of Testes

  5. Hormonal Control of Ovaries

  6. Female Hormone Levels • The ovarian cycle. (FSH, LH) • Development of a vesicular follicle, ovulation, and development of corpus luteum. • Under control of FSH and LH. • Follicular Phase - FSH promotes development of an ovarian follicle. • Luteal Phase - LH promotes development of corpus luteum.

  7. Uterine Cycle • Twenty-eight day cycle. (Estrogen, Progesterone) • Days 1-5 – Menstruation (menses). • Days 6-13 - Proliferative phase. • Day 14 - Ovulation. • Days 15-28 - Secretory phase.

  8. Estrogen and Progesterone • Estrogen and progesterone: • Foster development of reproductive organs. • Maintain uterine cycle. • Bring about female secondary sex characteristics . . . body hair, greater fat deposition under skin, pelvic girdle enlarges, wider hips, breast development.

  9. Fertiliztation • Or conception, is the union of a sperm and an ovum. • Typically thought that a woman ovulates 1 time per month. • However, a Canadian study on 63 women using ultrasound found that 9.5% of the women actually ovulated 2 times in a month!!! (New Scientist, July 19, 2003)

  10. Typically occurs in the upper third of the oviduct. • The cell that results from this union begins to divide (the zygote) and moves toward the uterus.

  11. Pregnancy • Within 5 – 10 days, the mass of cells arrives in the uterus and embeds itself into the uterine wall (implantation). • The wife is now pregnant and the mass of cells begins to produce human chorionic gonadotropic hormone (HCG) which prevents degeneration of the corpus luteum. • It is also the basis of the pregnancy test by being detected in the women’s blood and urine as early as 10 days after conception.

  12. Following implantation, the placenta originates from maternal and fetal tissues. • Placenta then produces human chorionic gonadotropin (HCG) which maintains the corpus luteum in the ovary until the placenta begins its own production of progesterone and estrogen. • Physical signs of pregnancy include no menstruation, increased urination, morning sickness, increased size of breasts, and darkening of areolae.

  13. During menopause, usually between age 45 and 55, the ovarian and uterine cycles cease. • The ovaries are no longer responsive to FSH and LH and stop producing estrogen and progesterone. • Often causes “hot flashes”, dizziness, headaches, insomnia, sleepiness, depression. • The symptoms can be both physical and psychological.

  14. Control of Reproduction • Birth control methods. • Abstinence. • Birth control pills. • Nuva-Ring – a clear, flexible vaginal ring that continuously releases a low dose of hormones and is as effective as the everyday pill • Intrauterine device (IUD). • Diaphragm. • Male condom. • Contraceptive implants. • Morning after pills. • Preven, mifepristone (RU-486).

  15. Infertility • Infertility is defined as the failure of a couple to achieve pregnancy after one year of regular, unprotected intercourse. • Estimated 15% of all couples. • Female causes. • Blocked oviducts. • Endometriosis. • Male causes. • Low sperm count. • Sperm abnormalities.

  16. Assisted Reproductive Technologies • Artificial Insemination by Donor (AID). • In Vitro Fertilization (IVF). • Originally called a “test tube baby” • Intracytoplasmic Sperm Injection (ICSI). Gamete Intrafallopian Transfer (GIFT). • Surrogate mothers

  17. Homeostasis • Sex hormones: • Stimulates fat deposition. • Influence bone growth and density. • Produce growth of skeletal muscle. • Exert feedback control over hypothalamus. • Influence cardiovascular health.

  18. Review • Male Reproductive System • Testes and Sperm • Hormonal Regulation • Female Reproductive System • Genital Tract • Hormonal Levels • Uterine Cycle • Fertilization and Pregnancy • Control of Reproduction • Infertility

  19. Male Reproductive System • Male gonads, testes, are suspended in scrotum. • Sperm are produced in testes and mature in epididymis. • Travel to vas deferens for storage. • Ejaculate from urethra. • Semen composed of sperm and secretions form the seminal vesicles, prostate gland, and bulbourethral glands.

  20. Male Reproductive System

  21. Orgasm in Males • Penis has a long shaft and an enlarged tip, glans penis. • During sexual arousal, autonomic nerve impulses cause erectile tissue to fill with blood. • Contractions that expel seminal fluid from the penis are part of the physiological and psychological manifestations of the male orgasm. • Around 400 million sperm contained in 3.5 ml of semen.

  22. Penis Anatomy

  23. The Testes • Testes begin to develop inside the abdominal cavity and descend into the scrotal sacs during last two months of fetal development. • Scrotum helps regulate temperature of testes. • Testes packed with seminiferous tubules with cells undergoing spermatogenesis. • Androgens secreted by interstitial cells in between seminiferous tubules.

  24. The Testes • Mature sperm have three distinct parts. • Head. • Nucleus covered by acrosome. • Middle Piece. • Provide energy for movement. • Tail. • Flagellum for movement.

  25. Testis and Sperm

  26. Female Reproductive System • Female gonads are paired ovaries. • Oogenesis is the production of an egg. • Ovulation is the process of an egg bursting from an ovary and entering an oviduct.

  27. The Genital Tract • Oviducts extend from uterus to ovaries. • Fertilization usually occurs in oviducts. • Developing embryo arrives in the uterus after several days and implants in the lining of the uterine wall (endometrium). • Oviducts join the uterus at its upper end, and at the lower end the cervix enters the vagina.

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