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Lecture notes

Menstrual Cycle made easy..

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Lecture notes

  1. 1. REPRODUCTION (CHAP.04) RIZWAN
  2. 2. MENSTRUAL CYCLE IN HUMAN FEMALE 1) It is the combination of Ovarian cycle and Uterine cycle. * Ovarian cycle= Released of mature egg from one ovary once in 28 days * Uterine cycle= Preparation(development) of uterus/womb for a possible pregnancy.
  3. 3. PHASES OF MENSTRUAL CYCLE There are 4 phases of menstrual cycle: a) Menstruation or “M” phase b) Follicle or “F” phase c) Ovulation or “O” phase d) Corpus Luteum or “L” phase
  4. 4. MENSTRUATION PHASE  It is the onset of bleeding.  Endometrium of uterus breaks off and starts flowing alongwith blood.  Discharge of blood and tissue debris of uterus from vagina.  Menstruation takes place when no fertilization or pregnancy has occurred.  First day is taken as beginning of the cycle.  Lasts about 5 days ( day 1 to 5)
  5. 5. FOLLICLE PHASE (FSH)  Phase after menstruation.  Ends with ovulation.  Duration: 7 days ( day 6 to 12)  Hormone: Follicle stimulating hormone (FSH)  This hormone stimulates the development of follicles in the ovary.  The one mature follicle with egg is called Graffian follicle.  Rest follicles degenerate.  FSH also act on the ovary to produce Estrogen from degenerated follicles.  Estrogen inhibits FSH.  Estrogen thickens uterine wall.
  6. 6. OVULATION PHASE (LH)  Duration: 3 days ( day 13 to 15)  Graffian follicle ruptures.  Ovulation occurs.  Mature egg is released from the ovary into Oviduct or Fallopian tube.  Luteinizing hormone causes ovulation.
  7. 7. CORPUS LUTEUM PHASE (PROGESTERONE)  Longest phase.  Duration: 12 – 14 days ( day 16 to 28)  Ruptured follicle changes into yellowish body called Corpus Luteum.  Corpus Luteum produces Progesterone.  This hormone maintains and increases the growth of internal lining ( endometrium) of the uterus.  If fertilization does not occur,then Corpus Luteum degenerates.  Progesterone secretion is decreased.  Internal lining of the uterus sloughs off with blood.  Again menstruation begins.  Cycle repeats again and again.

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