BIOH122 Human Biological Science 2 Session 22 Female Reproductive System 2 The Reproductive Cycle Bioscience Department Endeavour College of Natural Health endeavour.edu.au
Session Plan o The female reproductive cycle Hormonal regulation Phases of the cycle o Birth control methods o Ageing and the reproductive system Endeavour College of Natural Health endeavour.edu.au 2
The Female Reproductive Cycle Endeavour College of Natural Health endeavour.edu.au 3
The Female Reproductive Cycle o Female reproductive cycle: Include The ovarian cycle The uterine cycle The hormonal regulation of the cycles The cyclical changes in the breasts and the cervix Endeavour College of Natural Health endeavour.edu.au 4
Female Reproductive Cycle o Ovarian cycle: Changes in the ovary during and after maturation of an oocyte o The uterine (menstrual) cycle: involves changes in the endometrium of the uterus to receive a fertilized ovum. if implantation does not occur, the stratum functionalis is shed during menstruation Endeavour College of Natural Health endeavour.edu.au 5
Hormonal Regulation of Female Reproductive Cycle o Controlled by monthly hormone cycle of hypothalamus, anterior pituitary, and ovaries o Gonadotropin-releasing hormone (GnRH): Secreted by of Hypothalamus Stimulates the release of hormones from anterior pituitary: Follicle-stimulating hormone (FSH) Luteinizing hormone (LH) Endeavour College of Natural Health endeavour.edu.au 6
o FSH: o LH: Hormonal Regulation of Reproductive Cycle Initiates follicular growth Stimulates the ovarian follicles to secrete estrogens Stimulates further development of the ovarian follicles Stimulates the ovarian follicles to secrete estrogens Stimulates ovulation and promotes formation of the corpus luteum Stimulates the corpus luteum to secretes estrogens, progesterone, relaxin and inhibin Endeavour College of Natural Health endeavour.edu.au 7
Hormonal Regulation of Reproductive Cycle o Estrogens: six different types three in significant quantities beta-estradiol, estrone, and estriol. o Functions: Development and maintenance of female reproductive structures, secondary sex characteristics, and the breasts. Increase protein anabolism and build strong bones. Lower blood cholesterol. Moderate levels of estrogens in the blood inhibit the release of GnRH by the hypothalamus and secretion of LH and FSH by the anterior pituitary gland. Endeavour College of Natural Health endeavour.edu.au 8
o Progesterone: Hormonal Regulation of Reproductive Cycle Works with estrogens to prepare the endometrium for implantation and the mammary glands for milk synthesis. High levels of progesterone inhibit secretion of GnRH and LH. o Relaxin: Relaxes the uterus by inhibiting contractions every month During pregnancy, relaxes the pubic symphysis and helps dilate the uterine cervix to facilitate delivery. o Inhibin: Inhibits secretion of FSH and GnRH and, to a lesser extent, LH. Decreases secretion of FSH and LH toward the end of the uterine cycle. Endeavour College of Natural Health endeavour.edu.au 9
Overview of Hormonal Regulation Endeavour College of Natural Health endeavour.edu.au 10
Hormonal Changes Endeavour College of Natural Health endeavour.edu.au 11
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Overview of Female Reproductive Cycle Endeavour College of Natural Health endeavour.edu.au 13
Phases of the Female Reproductive Cycle o Four phases: o The menstrual phase o The preovulatory phase o Ovulation o The postovulatory phase Endeavour College of Natural Health endeavour.edu.au 14
Menstrual Phase: Days 1-5 o First day of menstruation is considered the beginning of the 28 day cycle o In the ovary (follicular phase) Under the influence of FSH, several primordial follicles develop into primary follicles and then into secondary follicles. In the uterus Declining levels of progesterone and estrogens stimulate release of prostaglandins that cause the uterine spiral arterioles to constrict. Glandular tissues die; stratum functionalis layer is sloughed off along with 50 to 150 ml of blood. Endometrium becomes very thin, about 2 5 mm Endeavour College of Natural Health endeavour.edu.au 15
Preovulatory Phase: Days 6-13 o The time between the end of menstruation and ovulation. o More variable phase in length than the other phases and accounts for most of the differences in length of the cycle Endeavour College of Natural Health endeavour.edu.au 16
Preovulatory Phase: Days 6-13 o In the ovary (follicular phase) Some of the secondary follicles in the ovaries begin to secrete estrogens and inhibin. By about day 6, a single secondary follicle in one of the two ovaries develop to become the dominant follicle Higher estrogen and inhibin secreted by the dominant follicle decrease the secretion of FSH, which causes other, less well-developed follicles to stop growing and undergo atresia. The dominant follicle develops into a mature (Graafian) follicle Graafian follicle enlarges and bulges at surface of the ovary; continually increase its production of estrogens Endeavour College of Natural Health endeavour.edu.au 17
Preovulatory Phase: Days 6-13 o In the uterus (proliferative phase) Estrogens secreted by growing ovarian follicles stimulate the repair of the endometrium cells of the stratum basalis undergo mitosis and produce a new stratum functionalis. As the endometrium thickens, the short, straight endometrial glands develop, and the arterioles coil and lengthen as they penetrate the stratum functionalis. The thickness of the endometrium approximately doubles, to about 4 10 mm. Endeavour College of Natural Health endeavour.edu.au 18
Ovulation: Day 14 o The rupture of the mature (Graafian) follicle and the release of the secondary oocyte into the pelvic cavity. o The high levels of estrogens during the last part of the preovulatory phase exert a positive feedback effect on hypothalamus and anterior pituitary. o Corpus hemorrhagicum results. Endeavour College of Natural Health endeavour.edu.au 19
Ovulation: Day 14 o Events of Ovulation: A high concentration of estrogens stimulates more frequent release of GnRH and LH. GnRH promotes the release of FSH and additional LH by the anterior pituitary. LH causes rupture of the mature (Graafian) follicle and expulsion of a secondary oocyte about 9 hours after the peak of the LH surge. o The ovulated oocyte and its corona radiata cells are usually swept into the uterine tube. Endeavour College of Natural Health endeavour.edu.au 20
Signs of Ovulation o Increase in basal body temperature o Changes in cervical mucus o Cervix softens o Mittelschmerz - pain Endeavour College of Natural Health endeavour.edu.au 21
Postovulatory Phase: Days 15-28 o Time between ovulation and onset of the next menstrual period. o The most constant phase: lasts for14 days o In the ovary (luteal phase): After ovulation, the corpus hemorrhagicum is formed from the ruptured follicle. under the influence of LH, Theca interna cells mix with the granulosa cells and all become transformed into corpus luteum cells. Stimulated by LH, the corpus luteum secretes progesterone, oestrogen, relaxin, and inhibin. The luteal cells also absorb the blood clot. Endeavour College of Natural Health endeavour.edu.au 22
Postovulatory Phase: Days 15-28 o If the oocyte is not fertilized: The corpus luteum survives for only 2 weeks and then degenerates into a corpus albicans Its secretory activity declines, and the levels of progesterone, estrogens, and inhibin decrease Release of GnRH, FSH, and LH rises due to loss of negative feedback suppression by the ovarian hormones. Follicular growth resumes and a new ovarian cycle begins. o If the secondary oocyte is fertilized and begins to divide: Human chorionic gonadotropin (hcg) is produced by the chorion of the embryo about 8 days after fertilization Corpus luteum survives longer due to hcg. Like LH, hcg stimulates the secretory activity of the corpus luteum. Endeavour College of Natural Health endeavour.edu.au 23
Postovulatory Phase: Days 15-28 o In the uterus (Secretory phase) Progesterone and estrogens promote growth and coiling of the endometrial glands, vascularization of the superficial endometrium, and thickening of the endometrium to 12 18 mm. The endometrial glands begin to secrete glycogen. o If fertilization does not occur: The levels of progesterone and estrogens decline due to degeneration of the corpus luteum. Withdrawal of progesterone and estrogens causes menstruation. Endeavour College of Natural Health endeavour.edu.au 24
Postovulatory Phase: Days 15-28 o If fertilization and implantation occurs: The corpus luteum is maintained by hcg. The corpus luteum and later the placenta secrete progesterone and estrogens to support pregnancy and breast development for lactation. Once the placenta begins its secretion, the role of the corpus luteum becomes minor. Endeavour College of Natural Health endeavour.edu.au 25
Female reproductive cycle: Summary
Birth Control Methods Endeavour College of Natural Health endeavour.edu.au 27
Birth Control Methods o Several methods of birth control are available, each with advantages and disadvantages. o Only total abstinence is 100% reliable. o Methods of birth control discussed in the text include surgical sterilization (vasectomy, tubal ligation), hormonal methods (oral contraception, the Norplant implant, Depo-Provera injection, the vaginal ring), intrauterine devices (IUDs), spermicides, barrier methods (condom, vaginal pouch, diaphragm, cervical cap), periodic abstinence (rhythm method, sympto-thermal method), coitus interruptus (withdrawal), and induced abortion (including the drug RU 486, or mifepristone). Endeavour College of Natural Health endeavour.edu.au 28
Surgical Sterilization o Male (vasectomy) removal of a portion of the vas deferens incision in posterior scrotal sac out patient and local anesthesia sperm can no longer reach the exterior degenerate and removed by phagocytosis sexual desire not effected since testosterone levels unchanged o Female (tubal ligation) uterine tubes are tied closed and cut sperm can not reach oocyte Endeavour College of Natural Health endeavour.edu.au 29
Hormonal Birth Control o Oral contraceptive - the pill progesterone and estrogen combination pill negative feedback on the anterior pituitary and hypothalamus to prevent secretion of FSH and LH no follicular development or ovulation no possible pregnancy other benefits of the pill regulate menstrual cycle and reduce endometriosis o Risks increased for smokers increased chances of blood clot formation o Not recommended for people with liver disease, hypertension, heart disease, migraines Endeavour College of Natural Health endeavour.edu.au 30
Other Hormonal Methods o Norplant surgically implanted capsules releasing progestin and inhibiting ovulation over 5 years o Depo-Provera intramuscular injection of progesterone every 3 months that changes uterine lining and ovum maturation o Vaginal ring worn internally releasing progestin or combination of progestin and estrogen Endeavour College of Natural Health endeavour.edu.au 31
Intrauterine Devices o Intrauterine devices: Small object made of plastic, copper or steel left in the cavity of the uterus- Copper T 380A, changes uterine lining so it is unfavorable for embryo implantation approved for 10 year usage o May cause excessive bleeding or discomfort Endeavour College of Natural Health endeavour.edu.au 32
Spermatocides o Spermatocides: Chemical substances in foam, cream, jelly, douche or suppository that kill sperm upon contact o Available without prescription o Normally used in conjunction with a barrier device o May inactivate HIV virus and decrease incidence of gonorrhea Endeavour College of Natural Health endeavour.edu.au 33
Mechanical Barriers o Male and female condoms (vaginal pouch) covers penis or lines vagina o Diaphragm = dome-shaped cap over cervix prevents entry of sperm into uterus does not protect against AIDS or STDs may cause recurrent UTIs o All of the above may offer some protection against sexually transmitted diseases Endeavour College of Natural Health endeavour.edu.au 34
Physiological Methods of Birth Control o Rhythm method (periodic abstinence) abstaining from intercourse when secondary oocyte is likely to be viable (3 to 7 days of the cycle) 3 days before ovulation, ovulation and 3 days after few women have absolutely regular cycles will not know it was an irregular cycle until too late o Sympto-thermal method observe body for signs of ovulation and abstain form intercourse accordingly increased basal body temperature and mucus changes problem is sperm is viable for 48 hours o Coitus interruptus: withdrawal before ejaculation Endeavour College of Natural Health endeavour.edu.au 35
Aging and the Reproductive Systems o Puberty refers to the period of time when secondary sexual characteristics begin to develop and the potential for sexual reproduction is reached. o In males, declining reproduction function is more subtle, with males often retaining reproductive capacity into their 80s or 90s. o In males, decreasing levels of testosterone decrease muscle strength, sexual desire, and viable sperm. o Prostate disorders are increasingly common with age, particularly benign hypertrophy. Endeavour College of Natural Health endeavour.edu.au 36
Aging and The Reproductive Systems Endeavour College of Natural Health endeavour.edu.au 37
Aging: The Female Reproductive System o In females, the reproductive cycle normally occurs once each month from menarche, the first menses, to menopause, the last menses. o Between the ages of 40 and 50 the ovaries become less responsive to the stimulation of FSH and LH. As a result, estrogen and progesterone production decline, and follicles do not undergo normal development. o In addition to the symptoms of menopause, such as hot flushes, copious sweating, headache, vaginal dryness, depression, weight gain, and emotional fluctuations, with age females also experience increased incidence of osteoporosis, uterine cancer, and breast cancer. Endeavour College of Natural Health endeavour.edu.au 38
Aging: Male Reproductive System o Decline in reproductive function is more subtle (capacity may remain into 90 s) o Decline in testosterone at 55 reduced muscle synthesis fewer viable sperm reduced sexual desire o Enlargement of prostate (benign hyperplasia) 1/3 of males over 60 frequent urination, decreased force of stream, bedwetting and sensation of incomplete emptying Endeavour College of Natural Health endeavour.edu.au 39
Reproductive System Disorders in Females o Premenstrual syndrome (PMS) o Endometriosis o Breast Cancer o Ovarian cancer o Cervical cancer o Vulvovaginal candidiasis Endeavour College of Natural Health endeavour.edu.au 40
Reproductive System Disorders in Males o Prostate Disorders: Acute prostatitis, chronic prostatitis, prostate cancer o Testicular Cancer o Premature ejaculation o Erectile Dysfunction (Impotence) Endeavour College of Natural Health endeavour.edu.au 41
Readings and Resources o Tortora, GJ & Derrickson, B 2014. Principles of Anatomy and Physiology, 14th edn, Wiley. o Harris, P, Nagy, S & Vardaxis, N 2010, Mosby s Dictionary of Medicine, Nursing and Health Professions, 2nd edn, Mosby Elsevier. o Guyton, AC & Hall, JE 2011, Textbook of Medical Physiology, 12th edn, Saunders Elsevier. o Marieb, EN & Hoehn, K 2011, Human Anatomy and Physiology, 9th edn, Benjamin Cummings Pearson. o Moore, KL, Dalley, AF & Agur, AMR 2010, Clinically Orientated Anatomy, 6th edn, Lippincott, Williams & Wilkins. Endeavour College of Natural Health endeavour.edu.au 42
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