19.01.2 Female Reproduction 2009


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19.01.2 Female Reproduction 2009

  1. 1. Chapter 19 <ul><li>19.1.2 </li></ul><ul><li>The Female Reproductive System </li></ul><ul><li>Pages 524 to 530 </li></ul>
  2. 2. Female Reproductive System <ul><li>You should be able to label a diagram with </li></ul><ul><ul><li>Ovary, Fallopian tubes, funnel of the oviduct (= Fallopian tubes, Uterus (with endometrium lining & Myometrium (muscles), cervix, vagina, external genitalia (= Clitoris, Vulva (labia minor & major) the position of rectum, anus, bladder, ureter, urethra & pelvic bone. </li></ul></ul><ul><li>See Diagram 19.5 P 525 </li></ul>
  3. 3. Human Female Reproductive System
  4. 4. Human Female Reproductive System
  5. 5. Ovaries <ul><li>Ovaries </li></ul><ul><ul><li>Size & shape of almond </li></ul></ul><ul><ul><li>Produce female gametes & female sex hormones </li></ul></ul><ul><ul><li>Consist of </li></ul></ul><ul><ul><ul><li>Inner medulla = connective tissue, blood vessels & mature follicles </li></ul></ul></ul><ul><ul><ul><li>Outer cortex = germinal epithelium produces ova </li></ul></ul></ul><ul><ul><li>Sit in abdominal cavity </li></ul></ul>
  6. 6. Oogenesis <ul><li>= production of female gamete = ovum </li></ul><ul><li>Begins BEFORE birth </li></ul><ul><li>Is only completed AFTER fertilisation </li></ul><ul><li>During foetal development, germ cells undergo repeated MITOTIC divisions to form DIPLOID PRIMARY OOCYTES </li></ul><ul><li>These stay at PROPHASE 1 of Meiosis until (beginning at female puberty) they are released from the ovary </li></ul>
  7. 7. Oogenesis (2) <ul><li>Each primary oocyte is enclosed in a single layer of follicle cells = Primary Follicle </li></ul><ul><li>200 000 produced by only about 450 develop into Haploid Secondary oocytes </li></ul><ul><li>Puberty – hormones from anterior pituitary cause a single primary oocyte continue the suspended meiosis </li></ul><ul><li>Forms Graafian Follicle = </li></ul><ul><ul><ul><li>Follicle cells several layers thick </li></ul></ul></ul><ul><ul><ul><li>Follicle is fluid filled </li></ul></ul></ul><ul><ul><ul><li>Primary oocyte to large secondary oocyte (proceeds to metaphase 2) & small polar body (often degenerates) </li></ul></ul></ul><ul><li>This follicle moves to surface of ovary </li></ul>
  8. 8. Oogenesis Diagram = Formation of Female Gamete
  9. 9. Fig 19.4 Page 524
  10. 10. Ovulation <ul><li>= secondary oocyte released from ovary </li></ul><ul><li>Follicle changes to form Corpus Luteum (yellow body) </li></ul><ul><li>This produces hormone Progesterone , associated with anticipated fertilisation & pregnancy </li></ul><ul><li>Released secondary oocyte drawn into one Fallopian tube (oviduct) by action to the funnel </li></ul><ul><li>Movement down oviduct caused by its ciliated epithelium & muscular contractions of its walls </li></ul><ul><li>Fertilisation occurs in oviduct (Fallopian tube) </li></ul><ul><li>Moves into uterus </li></ul>
  11. 12. Uterus <ul><li>Thick-walled, muscular organ, lined with glandular epithelium (endometrium) </li></ul><ul><li>Plentiful blood supply </li></ul><ul><li>Cervix = lower entrance to uterus </li></ul><ul><li>Narrow lumen closed by plug of mucus with acidic, antibacterial chemicals for protection against infection </li></ul><ul><li>Important as abdominal cavity is basically open to exterior via reproductive tract. </li></ul>
  12. 13. Vagina & external genitalia <ul><li>Cervix opens into vagina </li></ul><ul><li>Vagina = muscular organ, receives penis during intercourse </li></ul><ul><li>Clitoris = erectile organ, anterior to opening of vagina, homologous to penis </li></ul><ul><li>Vulva = two folds of tissue which enclose the openings of vagina & urethra, and the clitoris, glands release mucus if female is sexually aroused, aids lubrication for intercourse </li></ul>
  13. 14. External genitalia diagram
  14. 15. Summary of functions Organ of sexual intercourse, birth canal Vagina Secretion of mucus that enhances sperm movement into uterus & after fertilisation reduces embryo’s risk of bacterial infection Cervix Chamber in which baby develops Uterus Ducts conducting oocyte from ovary to uterus, fertilisation usually occurs here Oviducts Oocyte production & maturation, sex hormone production Ovaries Female Reproductive Organs
  15. 16. 19.1.3 Fertilization <ul><li>You have read & summarised this section & it has also been covered in other sections </li></ul><ul><li>Remember that Cowper’s Glands = Bulbo-urethral glands </li></ul><ul><li>Coitus = copulation </li></ul><ul><li>Sperm viable 72 hours but highly fertile 12 to 24 hours </li></ul><ul><li>Sperm entry of sperm head triggers formation of impenetrable Fertilisation membrane & completion of second meiotic division </li></ul><ul><li>Nuclei of the sperm and ovum unite to form Zygote </li></ul>
  16. 17. Case Study 19.2 <ul><li>Infertility which deals also with IVF </li></ul>
  17. 18. 19.1.4 Menstrual cycle <ul><li>Average 28 day cycle in females from puberty to menopause </li></ul><ul><li>Usually only interrupted by pregnancy </li></ul><ul><li>Hormones: </li></ul><ul><ul><li>FSH (follicle stimulating hormone) from anterior pituitary simultaneously STIMULATES </li></ul></ul><ul><ul><ul><li>Primary follicle to grow into Graafian follicle </li></ul></ul></ul><ul><ul><ul><li>Primary oocyte to start meiotic division </li></ul></ul></ul><ul><ul><ul><li>Ovarian tissue to produce Oestrogen </li></ul></ul></ul><ul><ul><li>Oestrogen repairs uterine wall from previous menstruation </li></ul></ul>
  18. 19. Separated cycles <ul><li>I have decided to separate out the ovarian cycle & uterine cycle & then you can use the text to bring them together </li></ul>
  19. 20. Stages in Ovarian Cycle <ul><li>Ovarian cycle = monthly series on events associated with the maturation of the egg </li></ul><ul><li>2 consecutive phases: </li></ul><ul><ul><li>Follicular phase = period of follicle growth, typically = 1 st to 14 th day of cycle </li></ul></ul><ul><ul><li>Luteal phase = period of corpus luteum activity, typically = days 14 to 28 </li></ul></ul><ul><ul><li>“ TYPICAL ” CYCLE = 28 days </li></ul></ul><ul><ul><li>Cycles as long as 40 days & as short as 21 days are common </li></ul></ul>
  20. 21. Ovarian cycle in straight line (Vesicular = Graafian) follicle
  21. 22. Ovarian cycle diagram Numbers = sequence in cycle NOT position in ovary
  22. 23. Ovarian cycle (Follicle Phase) <ul><li>Primordial follicle with primary oocyte </li></ul><ul><li>Follicle cells change shape </li></ul><ul><li>Growing follicle </li></ul><ul><li>Growing follicle (in 3&4 follicle producing oestrogen as it continues to mature) </li></ul><ul><li>Secondary follicle forming </li></ul><ul><li>Mature follicle, fluid filled, ready to ovulate, MEIOSIS I producing secondary oocyte & first polar body </li></ul>
  23. 24. OVULATION <ul><li>7. </li></ul><ul><li>Occurs when the ballooning ovary wall ruptures & expels the secondary oocyte surrounded by a corona of cells into the peritoneal (abdominal cavity) </li></ul><ul><li>About day 14 </li></ul><ul><li>Occurs in response to rising levels LH from anterior pituitary </li></ul>
  24. 25. Ovarian cycle (luteal phase) <ul><li>Corpus luteum formed from the ruptured follicle under the influence of LH, produces progesterone (& some oestrogen) IF pregnancy does not occur, this starts to degenerate in about 10 days & hormonal output ends </li></ul><ul><li>Scarlike corpus albicans (white body) </li></ul><ul><li>If oocyte fertilised & pregnancy occurs, corpus luteum persists until the placenta takes over hormone production (12 weeks) </li></ul>
  25. 26. FSH & LH levels
  26. 27. Ovarian Hormone levels
  27. 28. For interest <ul><li>Cervical mucus usually thick & sticky </li></ul><ul><li>BUT rising oestrogen levels causes it to thin and become crystalline, forming channels that facilitate passage of sperm </li></ul><ul><li>At ovulation basal metabolic temperature rises, and this if monitored in conjunction with observations of mucus change, indicates when ovulation occurs </li></ul><ul><li>Used for birth control or when is best time for copulation resulting in pregnancy </li></ul>
  28. 29. Feedback interactions of hormones (1) <ul><li>GnRH (Gonadotropin-releasing) hormone in pituitary gland </li></ul><ul><li>Childhood </li></ul><ul><ul><li>Ovaries grow & continually secrete small amounts of oestrogen which stop GnRH </li></ul></ul><ul><li>Puberty </li></ul><ul><ul><li>Hypothalmus {(P471) endocrine gland that acts on the anterior & posterior glands} becomes less sensitive to oestrogen & releases GnRH in pulses which causes the anterior pituitary to release FSH & LH </li></ul></ul><ul><ul><li>Occurs over 4 years & ends when hormonal interactions stabilise & adult cyclic pattern is achieved </li></ul></ul><ul><ul><li>First period indicates ovarian cycle established </li></ul></ul>
  29. 30. Feedback interactions of hormones (2) <ul><li>Hormonal events in Ovarian cycle </li></ul><ul><ul><li>GnRh stimulates anterior pituitary to release FSH (stimulates follicle production) & LH (stimulates oestrogen production) </li></ul></ul><ul><ul><li>When blood oestrogen levels reaches a certain level, POSITIVE FEEDBACK is exerted & causes a sudden release of LH that causes the primary oocyte to continue meiosis I & triggers ovulation, then causes the conversion of the ruptured follicle to corpus luteum & stimulates its secretory activity (FSH to lesser extent) </li></ul></ul>
  30. 31. Feedback interactions of hormones (3) <ul><ul><li>Rising levels of progesterone & oestrogen exert a strong NEGATIVE FEEDBACK (inhibitory) effect on anterior pituitary & so FSH & LH levels drop </li></ul></ul><ul><ul><li>LH decreasing = corpus luteum degenerates = osterogen & progesterone levels drop to their lowest level about days 26 to 28 & cycle begins again </li></ul></ul><ul><ul><li>If implantation of embryo occurs, it produces a LH-like hormone which maintains the activity of corpus luteum until the placenta takes over </li></ul></ul>
  31. 32. Interacting hormones
  32. 33. Uterine (Menstrual) Cycle <ul><li>Three Phases: </li></ul><ul><ul><li>Days 1 to 5 = Menstrual phase = shedding of functional layer of endometrium </li></ul></ul><ul><ul><li>Days 6 to 14 = Proliferative phase = rising oestrogen levels stimulates regeneration (rebuilding) of the endometrium, making the uterus ready for implantation of embryo, both events occur before ovulation </li></ul></ul><ul><ul><li>Days 15 to 28 = Secretory phase (begins immediately after ovulation) = enriches blood supplies, provides nutrients that prepares the endometrium for implantation of the embryo </li></ul></ul>
  33. 34. Uterine cycle diagram
  34. 35. Combined cycles & hormones see Fig 19.7 Page 529
  35. 37. PREGNANCY page 529 <ul><li>Ovum fertilised in fallopian tubes </li></ul><ul><li>Develops as it moves to uterus </li></ul><ul><li>Implanted into spongy uterine wall </li></ul><ul><li>= pregnancy </li></ul><ul><li>Corpus luteum persists: </li></ul><ul><ul><li>Produces progesterone & oestrogen </li></ul></ul><ul><ul><li>= maintains uterus & prevents FSH production </li></ul></ul><ul><ul><li>No FSH = No Follicle production </li></ul></ul><ul><ul><li>But corpus luteum breaks down after 3 months when placenta is fully functional (next chapter) </li></ul></ul>
  36. 38. PREGNANCY (2) p529 <ul><li>As pregnancy progresses these two hormones play vital roles (see Table 21.3) </li></ul><ul><li>At some point oestrogen levels continue to rise while progesterone levels fall </li></ul><ul><li>At a critical point between the two hormones, the POSTERIOR PITUITARY is stimulated to product OXYTOCIN which triggers uterine contractions= onset of birth = PATRURITION ending a GESTATION period of approximately 9 months </li></ul>
  37. 39. Figure 19.6
  38. 40. Figure 19.6
  39. 41. Development <ul><li>from conception to birth </li></ul>
  40. 42. Table 19.1 page 530 <ul><li>This gives the changed roles of ovarian hormones during pregnancy & is not for rote learning </li></ul>
  41. 43. Milk production <ul><li>Flow of milk is stimulated by PROLACTIN from anterior pituitary at birth </li></ul><ul><li>Due to sudden drop of levels of oestrogen & progesterone when the placenta (afterbirth) leaves the uterus </li></ul><ul><li>Post-natal depression can result from this drop in oestrogen </li></ul>
  42. 44. Self Help <ul><li>Read the Summary on pages 530 & 532 </li></ul><ul><li>Review Questions 19.1 to 19.4 </li></ul>
  43. 45. Extending your Ideas <ul><li>Do numbers: </li></ul><ul><ul><li>1, 2, 3 & 4 (All UB) </li></ul></ul>