The menstrual cycle

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The menstrual cycle

  1. 1. The menstrual cycle<br />
  2. 2. Physiology of menstruationthe ovaries...<br />1. Hypothalamus releases GnRH (LHRH)<br />2. Release of GnRH triggers APG to release FSH and LH<br />FSH- responsible for the maturation of ovum and follicle formation.<br />Causes an increase in estrogen<br />LH – triggers ovulation and growth of uterine lining<br />
  3. 3. 2.1 FSH activates primordial follicles to mature.<br />2.2 Primordial follicles start producing follicular fluid that is HIGH IN ESTROGEN (estradiol) and some progesterone<br />2.3 primordial follicles propelled toward the surface of ovary and is now called Graafian Follicle.<br />3. Graafian follicle undergoes cell division (mitosis, meiosis)<br />3.1 GF divides into:<br />3.1.a primary oocyte – with more cytoplasm<br />3.1.b secondary oocyte – with less cytoplasm<br />3.2 GF after meiosis contain haploid cells (23 chromosomes)<br />
  4. 4. 4. Upsurge in LH causes the release of prostaglandin<br />5. Prostaglandin causes the rupture of GF releasing ovum and follicular fluid from the follicle, leaving the follicle with a hollowed pit.<br />6. Increase in LH causes production of Lutein (bright yellow fluid, HIGH IN PROGESTERONE) that will fill the empty pit<br /> 7. Follicle becomes “CORPUS LUTEUM”<br />
  5. 5. 7.1 if fertilization occurs, ovum implants at the uterus, corpus luteum stays inside the ovaries until 16-20 weeks; trophoblast begin secreting HCG<br />7.2 without fertilization, ovum atrophies after 4-5 days, CL remains for only 8-10 days.<br />7.2.a CL replaced by white fibrous tissue, CL becomes “CORPUS ALBICANS”<br />
  6. 6. Physiology of menstruationthe uterus...<br />1st PHASE: PROLIFERATIVE (aka estrogenic/follicular/postmenstrual)<br /><ul><li>High levels of estrogen causes thickening and proliferation of endometrium
  7. 7. LH is increased, Estrogen is increased</li></li></ul><li>2nd PHASE: SECRETORY (aka: progestational/luteal/premenstrual)<br /><ul><li>Increased levels of progesterone causes glands at endometrium to become cork screw like or twisted in appearance and dilated with quantities of glycogen and mucin
  8. 8. Increased in capillaries making endometrium appear like a rich spongy velvet
  9. 9. Decreased LH, Increased Progesterone</li></li></ul><li>3RD PHASE: ISCHEMIC<br /><ul><li>Decreased estrogen and progesterone levels causes the degeneration of the endometrium
  10. 10. Capillaries rupture, endometrium sloughs off</li></li></ul><li>4TH PHASE: MENSES/MENSTRUAL FLOW<br /><ul><li>menses is composed of:
  11. 11. Blood from the ruptured capillaries
  12. 12. Mucin from glands
  13. 13. Fragments of endometrial tissue
  14. 14. Microscopic, atrophied, unfertilized ovum
  15. 15. Total blood loss: 30-80ml
  16. 16. Iron loss: 11mg</li></li></ul><li>
  17. 17. Physiology of menstruationthe cervix...<br />1st half of the cycle<br /><ul><li>Hormones decreased
  18. 18. Mucus thick and scanty
  19. 19. Poor sperm survival</li></ul>Ovulation <br /><ul><li>Estrogen is increased
  20. 20. Cervical mucus thin and copious
  21. 21. Excellent sperm survival</li></ul>2nd half<br /><ul><li>Decreased progesterone level
  22. 22. Mucus is thick
  23. 23. Poor sperm survival</li></li></ul><li>

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