menstrual cycle

1. Physiology of menstrual
cycle
Unit - II

2. Introduction
 Typically a women of child bearing age or
reproductive age (15 -45 years) should menstruate
every 28 days or so unless she is pregnant or moving
into menopause .
 Amenstrual cycle consist of natural changes that
occur in a women body every month in prepration for
pregnancy .
 Menstruation starts at puberty and ends at
menopause
 Eumenorrhea is term for normal
menstruation

3. Definition
 Menstruation means cyclic uterine bleeding caused
by shedding of progestational endometrium. It
occurs between menarche and menopause .
 Menstruation is also called menstrual bleeding,
menses or periods.
OR
 The cyclic events that takes place in a rhythmic
manner during the reproductive period of a
woman’s life is called menstrual cycle.

4. Characterstics
1. Menarche :- First occurance of
menstruation . Starts at 12 to 16 years .
Average 14 years .
2. Menopause :- Permanent cessation of
menstrual cycle . Usually at 45- 50 years.
3. Duration :-2 to 7 days ( < 2 days in
hypomenorrhea and >7 days in menorrhagia.
4. Amount :- 30 to 80 ml. >80 ml is menorrhagia &
<30 ml is hypo menorrhea.

5. Contd…
• 5 . Coagulation :-
 Some authors state that the mixture of mucus with
menstrual blood prevents the clotting of the
menstrual blood .
 Others state that the acidity of vaginal secretion is
responsible for non coagulibility .
 Some states that it does not clot due to
present in endometrial debris .

6. Hypothalmic - Pituitary
OvarianAxis
Hypothalmus
Gland
Secrete Gonadotrophin Releasing
Harmones
FS
H
L
H

7. Phases in menstrual cycle
 There are 2 main components of the menstrual
cycle :-
1. Ovarian Cycle
2. Uterine Cycle
 Ovarian Cycle :- Changes happen in
ovaries in response to pituitary harmones .
 Uterine Cycle :- Changes that takes place
in the uterus .
 But it is important to remember that both cycles
work simultaneously to produce menstrual cycle .
 Changes in the cervical mucus also takes place
during menstrual cycle .

8. Ovarian cycle
 The ovarian cycle refers to periodic changes
that occur in the ovary every month during the
female reproductive life .
 Cyclical changes in the ovaries occur in response to
2 anterior pituitary harmones .
1. Follicle stimulating harmone (FSH)
2. Luteinizing harmone (LH)

9. Uterine cycle
 The uterine cycle refers to changes that are found in
the lining of the uterus
 The changes come about in response to the ovarian
harmones :-
 Estrogen
 Progesterone

11. Phases of menstrual cycle
 There are 4 phases of menstrual cycle .
1. Menstrual phase
2. Follicular OR preovulatory OR
proliferative phase
3. Ovulation OR Ovulatory phase
4. Luteal OR Post ovulatory OR secretary Phase

12. Menstrual phase
 It is called Bleeding phase .
 Average duration of this phase is 3-5 days .
 Day 1 of the menstrual cycle is marked by onset
of menstruation.
 During the menstrual phase the uterine lining is shed
 The menstrual flow consist of the secretions from the
endometrial gland , endometrial cells , blood from
the degenerating capillaries and unfertilized ovum.
 The menstrual phase ends when menstrual period stops
on day 5.

13. Follicular &Pre ovulatory
and Proliferative phase
 This phase of the cycle extends from the day 5th of
the menstrual phase till the time of ovulation .
 This phase generally lasts for 8-9 days .
 During this phase some 10 - 15 primordial follicles
start maturing .
 But only one follicle of one of the ovaries reaches
maturity.The mature follicle is called which
secretes estrogen .
 Estrogen has a negative feedback on the FSH .
 This is to stop the other follicles from maturing .

14. OVULATORY PHASE
 Estrogen peak stimulates the secretion of LH.
 LH peak leads to :-
The follicle to burst open releasing the mature ovum .
This is called as ovulation .
 Ovulation occurs on 14 th day of each 28 day cycle

15. POSTOVULATORY or
SECRETARY PHASE
 This phase starts from day 15 and last till
the end of cycle that is from day 15 to 28.
 After ovulation LH levels remains elevated
and cause the remnants of the follicle to
develop into a yellow body called corpus
luteum .
 Corpus luteum secretes mainly Progesterone and
some oestrogen
• These 2 harmones function to maintain the lining of
the uterus that is endometrium and prepare it for
pregnancy

17. Luteal phase
 When there is no fertilization for about 7-8 days
then degeneration of corpus luteum starts .
 Due to corpus luteum degeneration level of
estrogen and progesterone also falls down .
 Corpus luteum then changes to corpus albicans
and then it is reabsorbed .
 Cells or lining of endometrium develops
a condition of ischemia . So they starts to fall
down or there shedding starts .
 And women is once again at the day 1 of
menstrual cycle .

20. CERVICAL MUCUS
CHANGES
 Changes in cervical mucus takes place over the
course of the menstrual cycle.
 During the menstrual phase the mucosa of cervix
does not undergo shedding off like endometrium.
 As proliferative phase begins the cervix begins to
produce a thin watery alkaline secretions .
 At the time of ovulation the cervical mucus is
thinnest and its elasticity is maximum. .

21. Contd…
 It can be stretched like a long thin elastic thread upto 8
to 12 cm . This is called Spinnbarkeit Effect . This
nature of cervical mucus favours the tansport of
sperms in the female genital tract and makes the
condition favourable for fertilization .
 After ovulation cervical secretions decrease in quantity
and becomes thick . These changes make a plug and
prevent entry of sperm through cervical canal .