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. 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. 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. 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. 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. 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.
