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11-8-06

11-8-06. For next time: read thoroughly the sections on labor & delivery; Lactation; Contraception Ch 15 Gall Bladder case study. Quick survey: Approx score last exam (nearest 10 pts) Did you study in a group? Did you study at least 6 hrs/week every week b/t exams (not average)?

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11-8-06

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  1. 11-8-06 • For next time: read thoroughly the sections on labor & delivery; Lactation; Contraception • Ch 15 • Gall Bladder case study. • Quick survey: • Approx score last exam (nearest 10 pts) • Did you study in a group? • Did you study at least 6 hrs/week every week b/t exams (not average)? • Did you ensure that you could fulfill all objectives?

  2. Female Reproductive System Before we get going, take 1 min and compare and contrast M & F systems: • M: continuous Sperm Prod. Vs F – 1 egg/month • M: releases gamete vs. F: retains & nurtures fertilized gamete • F: regulates environment over cycle • F: Hormones control release of egg • F: Egg cell cycle control complex (long) & 1 ovum / oogonia

  3. Figure 17-13 Path for spermatozoa ejaculated into the female reproductive tract: Vagina  cervix  uterus  fallopian tube Path for egg: ovaries fallopian tube (combined actions of fimbrial contractions and the oviduct’s “ciliary escalator.”)

  4. Question #2: Describe the various stages from oogonium to mature ovum • Oogonia  Mitosis & Differentiation Primary oocyte; meiotic arrest • Follicles (1 egg & supporting tissue) • Primordial follicle = egg + granulosa • 1˚ = larger egg + zona pelucida (layer of material), proliferation of ganulosa • Pre-antral follicle multiple granulosa layers, • Antral follicle antrum (fluid-filled space) forms

  5. Female Hormonal Control • Menstrual Cycles • As W/males, HPA control • GnRH  FSH, LH release  sex hormones • Long and short loop feedback • Resulting in • Cyclical gamete release • Preparation of uterus for implantation, nurturing • If not, then menstruation

  6. Note: Fig 17-18 Summarizes the “BIG PICTURE” tying everything together between HPA, Ovaries and UterusThe 1st portion of the questions covers ovarian events of the menstrual cycle; The later questions, cover uterine events linking them to ovarian cycle

  7. Q # 4: Name 3 hormones produced by the ovaries and name the cells that produce them • Estrogen (s) --- Granulosa Cells (follicular phase); Corpus luteum (luteal phase) • Progesterone --- granulosa and theca (little) before ovulation; corpus luteum (luteal phase) • Inhibin --- Granulosa Cells & Corpus luteum

  8. Q #6: What are the analogies between the granulosa cells and the sertoli cells and between the theca cells and the Leydig cells? • Sertoli and granulosa • support gametes • Respond to FSH • secrete chemicals that directly stimulate gamete development • Inhibin • Leydig and Theca • Both secrete androgens • Both respond to LH • Secretions of both feed back to hyp and AP

  9. New edition has error in this figure... FSH & LH switched (17-19) Q #7: List the effects of FSH on the follicle • 1st wk: levels of FSH,LH low, but enough that • FSH stimulates follicle dev.; granulosa cells to divide and produce estrogen; Estrogen acts as an auto-/paracrine agent  more estrogen secretion • LH stimulates theca cells to release androgens needed by granulosa cells for estrogen production

  10. Q #8: Describe the effects of estrogen and inhibin on gonadotropin secretion ... • Early & Mid: • Estrogen short loop to AP inhibits FSH & LH release • Decrease in FSH & LH at this time causes atresia of non-dominant follicles • Estrogen long loop to hyp: inhibits GnRH releases • Inhibin: inhibits mainly FSH • Late: everything changes!!! • High levels of estrogen enhance AP sensitivity to GnRH (mainly LH-releasing cells)  LH surge  ovulation

  11. Q # 9: List the effects of the LH surge on the egg and the follicle He he he... Couldn’t have said it better myself:

  12. Q #10: What are the effects of the sex steroids and inhibin on gonadotropin secretion during the luteal phase • IN THE PRESENCE OF ESTROGEN high progesterone suppresses GnRH and gonadotropin release • Inhibin: feeds back to AP and inhibits FSH release • (Fig 17-18)

  13. Q #11: Describe the hormonal control of the CL in a non-pregnant and in a cycle when pregnancy occurs • No pregnancy: low LH keeps CL going for ca. 2 weeks; sensitivity drops off over time and CL degenerates  lower estrogen/progesterone  menstruation & releases feedback suppression of gonadotropin release • W/ /pregnancy: hCG  from placenta sustains CL for about 2 mos. So that it secretes estrogen and progesterone for the uterus.

  14. Q # 12: What happens to the sex steroids and the gonadotropins as the CL degenerates? • Sex steroid levels drop off (uterine effects?) • Alleviates negative feedback inhibition of gonadotropin release which increases a bit, thus triggering the development of a new set of follicles

  15. Q # 13: Compare the phases of the menstrual cycle according to uterine and ovarian events • This is part of figure 17-22

  16. Q #14: Describe the effects of estrogen and progesterone on the endometrium, cervical mucous, and myometrium • Estrogen (follicular phase): proliferation of endometrium; development of myometrium; receptors for progesterone (endometrial cells) • Estrogen & Progesterone (luteal phase): • Progesterone inhibits myometrial contractions • Increase glandular activity of endometrium • Increase glycogen content of endometrium • Increase vascularization of endometrium • Changes cervical mucous from watery and abundant to sticky viscous plug (bacterial blockade)

  17. Q #15: Describe the uterine events associated with menstruation • Drop in estrogen and progesterone  prostaglandins  vasoconstriction  lack of oxygen/nutrients leads to degeneration of endometrium • Myometrium begins undergoing contractions • Later  vasodilation  bleeding

  18. Pregnancy • Fertilization of Egg = Zygote Formation • Cleavage turns zygote into Conceptus • For now, composed of all totipotent cells • For 3-4 d, conceptus stuck in fallopian tube b/c of estrogen mediated contraction of opening to uterus

  19. Pregnancy • ~ d 17: • progesterone relaxes opening to uterus • conceptus released floats freely for ~ 3 d. • differentiates; by the end its cells are no longer totipotent • Becomes a Blastocyst • Outer layer = trophoblast • Inner Cell mass --> eventually becomes embryo @ 2 months embryo = fetus

  20. Pregnancy • ~ d 21: implantation occurs • Sticky Trophoblast cells • Proliferative when in contact w/ endometrium • Secrete proteolytic enzymes, paracrine agents: facilitate entry of blastocyst into endometrium • Secrete Chorionic Gonadotropin (CG) • Remember CG Maintains CL until the placenta is formed • Estrogen and Progesterone to maintain endometrium

  21. Pregnancy • Initially, endometrial cells directly nourish bastocysts • After the first few weeks the Placenta takes over nutrition, environmental control

  22. Q # 24: State the sources of estrogen and progesterone during the different stages of pregnancy. What is the dominant estrogen of pregnancy and how is it produced? • Estrogen • 1st Corpus luteum, after ca. 60-80 d, Placenta becomes main source; promotes myometrial development • Main estrogen = Estriol • Progesterone • 1st Corpus luteum, after ca. 60-80 d, Placenta becomes main source • Inhibits contractions

  23. Q #25: What is the state of gonadotropin secretion during pregnancy and what is the cause? • CG • High for 2-3 months when it stimulates est. & prog. from CL • Then placenta takes over • LH/FSH levels • Low throughout pregnancy • B/c GnRH secretion is inhibited by high levels of progesterone in presence of estrogen • Prevents development of additional follicles/eggs

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