PHYSIOLOGY OF

MENTRUATION

INTRODUCTION

MENSTRUATION—Periodic discharge of blood along with other materials from the female genital tract.

MENSTRUAL CYCLE—Regular repetition of events from one menstruation to next.

Uterine event is the most prominent change

DURATION AND FLOW

Menstrual bleeding is normally painless & contains no clot.

Periodicity &duration of bleeding is remarkably constant in particular women.

Duration of cycle=28+4 days. Duration of bleeding=4-5 days. Amt. of bleeding=40ml.

Menorrhagia –if bleeding is more than 80ml.

Blood is mainly arterial & contains shredded endometrium, its rich in PG’s

Fibrinolysins prevent the clotting of blood, but if the bleeding is more — clotting does occur.

ENDOMERTRIAL CHANGES--SUMMARY Endometrium—mucous memb.

Lining the uterine cavity. 1).During menstruation (i.e. at

the end of leuteal phase)superficial 2/3rd endometrium k/a STRATUM FUNCTIONALE is shed off.

2).Basal 1/3rd endometrium k/a STRATUM BASALE grows in proliferative phase.

SUBDIVISIONS OF CYCLE

A)Pre ovulatory phase-(1)bleeding phase=4days(1st to 4th day-varies b/w 1-9days) (2)Proliferative phase=10days(5th day to ovulation)

B)Ovulation-14th day C)Postovulatory phase- Secretary

phase 15th to 28th day.

PHASES OF MENSTRUAL CYCLE

Proliferative phase

(1).PROLIFERATIVE PHASE #Starts after cessation of

menstruation. #Duration =10days(highly

variable) #Endometrium starts healing

slowly at 1st ,then proliferates rapidly 4m 5th -14th day.

#After bleeding ends endometrium is, 2mm thick &consists of ciliated columnar epi.

#Proliferation occurs in glands, blood vessels, stroma &superficial epi until the endometrium becomes approx 4mm thick.

#Uterine glands in length but remain non secretory.

#There is in contractions of endometrium.

#These changes are brought abt under the influence of estrogen which is secreted 4m developing follicle.

#Cervical secretions ----increase in volume ----becomes watery & alkaline ----promotes the survival& transport of sperms ----dries in a fern like pattern when spread on a slide

Ovulation

(2).OVULATION #OVARIAN CYCLE-----at menarche

hypothalamic maturation leads to cyclic ovulation

#During each cycle of approx 1month ,10-15 follicles enlarge to become 2 follicles, under the influence of FSH 4m ant pituitary.

#Fluid accumulates in these follicles, but out of 15 only 1enlarged follicles proceed to 2nd stage of ovulation

#This ovum gets covered by zona pellucida & granulosal cells, its k/a CUMMULUS OOPHARICUS & its picked by fimbriated end of fallopian tubes.

#Then the follicles rupture & ovum is released.

#At the time of ovulation antral fluid escapes & the follicle wall collapses leading to h’age into theca interna & thus forms CORPUS HAEMORRAGIUM

#After ovulation capillaries 4m theca interna invade the rapidly dividing granulosa layer & clotted blood is replaced with yellowish lipid rich leuteal cells forming CORPUS LEUTUM

#Corpus leuteum enlarges for 8-9days during which leuteal cells secrete estrogen & progesterone

#At abt 14th day of menstrual cycle , ovulation occurs(at this time cervical mucous is watery thin)

Secretory phase

(3)SECRETORY PHASE #Represents preparation of uterus

4 implantation of fertilized ovum. #Duration=14days(usually

constant) #Starts after ovulation & extends

up to next bleeding #36hrs after ovulation corpus

leuteum is well formed in the ovary & endometrium undergoes further development to become 6mm thick.

#Glands secrete mucous, in length & dia, become tortuous & are filled with secretions (SAW TOOTH APPEARENCE)

#Stromal cells proliferate & enlarge #Spiral arteries become coiled &

dilated and veins become filled with blood.

#All these changes are progesterone dependent. Progesterone also inhibits the myometrium—this prevents the expulsion of implanted ovum.

#Cervical secretions become thick, tenacious & cellular forming a viscous plug which constitutes a barrier b/w spermatozoa & microorganisms.

Menstrual Phase

(4)MENSTRUAL PHASE #If ovum is not fertilized, corpus

leuteum starts regressing 4m 24th day of the cycle.

#Due to regression of corpus leuteum, estrogen & progesterone secretion decreases & becomes very low.

#The enometrium shrinks without hormonal support and coiled arteries get further coiled spasm of arteries stoppage of blood flow focal necrosis of endometrium hemorrhage.

HORMONAL CHANGES IN

MENSTRUAL CYCLE

RAMAN

Hypothalamus Pituitary Axis

HYPOTHALAMUS

GnRH

ANTERIOR PITUITARY

FSH &LH

OVARY

OESTROGEN & PROGESTRONE

Hormones produced:

-Luteinizing hormone

-follicle stimulating hormone

-oestrogen

-progestrone

Pituitary gland

Uterus

Luteinizing hormone & follicle stimulating hormone:-

promote ovulation

Oestrogen & progestrone:-

stimulate the uterus & breast for

fertilization

Menstrual phase Bleeding occurs after estrogen and

progesterone levels decrease at the end of the previous cycle

About this time, the follicle-stimulating hormone level increases slightly, stimulating the development of several ovarian follicles

Later, as the follicle-stimulating hormone level decreases, only one follicle continues to develop.

This follicle produces estrogen

Ovulatory phase The ovulatory phase begins with a surge in

luteinizing hormone and follicle-stimulating hormone levels

Luteinizing hormone stimulates egg release (ovulation), which usually occurs 16 to 32 hours after the surge begins

The estrogen level peaks during the surge, and the progesterone level starts to increase

Luteal phase During the luteal phase, luteinizing hormone and

follicle-stimulating hormone levels decrease The ruptured follicle closes after releasing the egg

and forms a corpus luteum, which produces progesterone

During most of this phase, the estrogen level is high

Progesterone and estrogen cause the lining of the uterus to thicken more, to prepare for possible fertilization

If the egg is not fertilized, the corpus luteum degenerates and no longer produces progesterone, the estrogen level decreases and a new menstrual cycle begins

CONCLUSION

ANSHUL

Topic discussed today

MENSTRUATION

periodic discharge of blood along with other materials from the female genital tract

MENSTRUAL CYCLE

regular repetition of events from one menstruation to next

Duration & flow: Duration of cycle=21-35 days Duration of bleeding=4-5 days Amt. of bleeding=40ml

Menorrhagia: If bleeding is more than 80ml

Subdivisons of the cycle: A)Pre ovulatory phase-(1)bleeding

phase=4days (2)Proliferative phase=10days

B)Ovulation-14th day C)Postovulatory phase- Secretary phase

15th to 28th day

Phases of Menstrual cycle

1.Proliferative phase: Starts after cessation of menstruation. Duration =10days Proliferation occurs in glands, blood vessels,

stroma & superficial epithelium until the endometrium becomes approx 4mm thick.

These changes are brought about under the influence of estrogen which is secreted from developing follicle

2.Ovulation: At menarche hypothalamic maturation

leads to cyclic ovulation At about 14th day of menstrual cycle ,

ovulation occurs in 28 day cycle

3)SECRETORY PHASE: Represents preparation of uterus 4

implantation of fertilized ovum Duration=14days Starts after ovulation & extends up to next

bleeding This phase is under control of

progesterone

(4)MENSTRUAL PHASE If ovum is not fertilized, corpus luteum

starts regressing from 24th day of the cycle Due to regression of corpus luteum,

estrogen & progesterone secretion decreases & becomes very low which leads to shedding of endometrium

Hormonal changes

Hormones produced: -Luteinizing hormone

-follicle stimulating hormone

-oestrogen

-progestrone LH & FSH- promote ovulation Estrogen & Progesterone- stimulate the

uterus & breast for fertilisation

Menstrual phase: Bleeding occurs after estrogen and progesterone levels decrease As the follicle-stimulating hormone level decreases, only one follicle

continues to develop which produces estrogen

Ovulatory phase: Begins with a surge in luteinizing hormone and follicle-stimulating

hormone levels The estrogen level peaks during the surge, and the progesterone

level starts to increase

Luteal phase: Luteinizing hormone and Follicle-stimulating hormone levels decrease If the egg is not fertilized, the corpus luteum degenerates and no

longer produces progesterone, the estrogen level decreases and a new menstrual cycle begins