Female Reproductive Female Reproductive SystemSystem

Anatomy of the female sexual organsAnatomy of the female sexual organs

Monthly ovarian cycle:Monthly ovarian cycle:Monthly rhythmical changes in the Monthly rhythmical changes in the rates of secretion of female hormones rates of secretion of female hormones & corresponding physical changes in & corresponding physical changes in the ovaries & other sexual organsthe ovaries & other sexual organs..

Duration of the cycleDuration of the cycle average 28 days average 28 days (20-45 days). There are 2 results of (20-45 days). There are 2 results of the female sexual cycle:the female sexual cycle:1-Single ovum is released from the 1-Single ovum is released from the ovaries each monthovaries each month

22 - -Uterine endometrium is prepared for Uterine endometrium is prepared for implantation for the fertilized ovumimplantation for the fertilized ovum..

Gonadotropic hormones and their Gonadotropic hormones and their effects on the ovarieseffects on the ovaries::

The ovarian changes during the sexual The ovarian changes during the sexual cycle depend on FSH & LH secreted by cycle depend on FSH & LH secreted by AP. In the absence of these hormones, AP. In the absence of these hormones, the ovaries remain inactive throughout the ovaries remain inactive throughout childhood, childhood, at pubertyat puberty the AP starts to the AP starts to secrete FSH & LH which lead to the secrete FSH & LH which lead to the beginning of monthly sexual cycles. beginning of monthly sexual cycles. First menstrual cycle is called First menstrual cycle is called menarchemenarche..Both FSH and LHBoth FSH and LH stimulate their ovarian stimulate their ovarian target cells by combining with highly target cells by combining with highly specific receptors lead to increase the specific receptors lead to increase the cells rates of secretion, growth & cells rates of secretion, growth & proliferation of the cellsproliferation of the cells..

Ovarian follicle growthOvarian follicle growth-:-:

““Follicular” phase of the ovarian cycleFollicular” phase of the ovarian cycle::

--In female child each ovum is surrounded by In female child each ovum is surrounded by single granulosa cell sheath called single granulosa cell sheath called

primordial follicleprimordial follicle . . - -During childhood, the During childhood, the granulosa cellsgranulosa cells provide provide

nourishment for the ovum & secrete oocyte nourishment for the ovum & secrete oocyte maturation inhibiting factor which keeps maturation inhibiting factor which keeps the ovum in its primordial statethe ovum in its primordial state . .

- -After puberty,After puberty, AP secrete AP secrete FSH and LHFSH and LH which which stimulate the ovaries with some follicles to stimulate the ovaries with some follicles to grow. This begins with enlargement of the grow. This begins with enlargement of the ovum to increase in size & growth of ovum to increase in size & growth of additional layers of granulosa cells of some additional layers of granulosa cells of some follicles & known as follicles & known as primary folliclesprimary follicles..

During the first few days of the monthly female sexual During the first few days of the monthly female sexual cycle there is increase secretion of cycle there is increase secretion of FSH and LHFSH and LH,,

--FSH increase is slightly more & earlier than LH which FSH increase is slightly more & earlier than LH which causes the acceleration of growth of many primary causes the acceleration of growth of many primary follicles each month. There is proliferation of the follicles each month. There is proliferation of the granulosa cells to many layers. The ovary granulosa cells to many layers. The ovary interstitium collect in several layers outside the interstitium collect in several layers outside the granulosa cells to form a second mass of cells called granulosa cells to form a second mass of cells called

thecatheca..

This theca is divided into 2 layersThis theca is divided into 2 layers:: 11 ) )theca interna, the cells have epitheloid theca interna, the cells have epitheloid

characteristics and similar to the cells and secrete characteristics and similar to the cells and secrete sex hormones (estrogen and progesterone)sex hormones (estrogen and progesterone)

22 ) )theca externa, the outer layer, develops into a highly theca externa, the outer layer, develops into a highly vascular connective tissue capsule of the developing vascular connective tissue capsule of the developing folliclefollicle..

Few days after proliferation & growth of the follicles, Few days after proliferation & growth of the follicles, the granulosa cells secrete the granulosa cells secrete follicular fluidsfollicular fluids contain contain high concentration of estrogen. This fluid high concentration of estrogen. This fluid accumulate to form accumulate to form antrumantrum within the mass of the within the mass of the granulosa cellsgranulosa cells..The early growth of the follicle up to the antral is under The early growth of the follicle up to the antral is under FSHFSH stimulation. Then there is accelerated growth of stimulation. Then there is accelerated growth of the follicles to larger follicle called the follicles to larger follicle called vesicular folliclesvesicular follicles caused bycaused by-:-:

11 ) )estrogen secreted into the follicle caused the estrogen secreted into the follicle caused the granulosa cells to increase FSH receptors which granulosa cells to increase FSH receptors which causes causes positive feedback effectpositive feedback effect ; ;

22 ) )both estrogen & FSH combine to promote LH both estrogen & FSH combine to promote LH receptors on the granulosa cells, allowing more receptors on the granulosa cells, allowing more increase follicular secretionincrease follicular secretion;;

33 ) )the increasing estrogen from the follicle plus the increasing estrogen from the follicle plus

increasing LH from the AP causes proliferation of the increasing LH from the AP causes proliferation of the follicular theca cells & increase their secretionfollicular theca cells & increase their secretion..

The antral follicles begin to grow. The ovum The antral follicles begin to grow. The ovum enlarges & remain embedded at one pole of enlarges & remain embedded at one pole of the granulosa cells of the folliclethe granulosa cells of the follicle..

- -Only one follicle continue to grow & the Only one follicle continue to grow & the remaining follicles (5 to 11) undergo atresia remaining follicles (5 to 11) undergo atresia or involute the cause is unknown or could be or involute the cause is unknown or could be that large amount of estrogen from the that large amount of estrogen from the growing follicle inhibit further FSH growing follicle inhibit further FSH secretion from the AP, while the largest secretion from the AP, while the largest follicle continue to grow because of the follicle continue to grow because of the positive feedback effect & mature follicle positive feedback effect & mature follicle reach about 1 to 1.5 cmreach about 1 to 1.5 cm..

OvulationOvulation::It occurs 14 days after the onset of menstruation in 28 It occurs 14 days after the onset of menstruation in 28 days cycle. Before ovulation, small area in the center of days cycle. Before ovulation, small area in the center of the follicle called stigma protrude & fluids ooze from the follicle called stigma protrude & fluids ooze from the follicle & the stigma ruptures allowing more viscous the follicle & the stigma ruptures allowing more viscous fluid outward carrying with it the ovum surrounded by fluid outward carrying with it the ovum surrounded by mass of granulosa cells called mass of granulosa cells called corona radiatacorona radiata..

LH surge is necessary for ovulationLH surge is necessary for ovulation::22 days before ovulation, the rate of LH secretion from the days before ovulation, the rate of LH secretion from the

AP increase markedly to 6-16 fold & peak about 16 hrs AP increase markedly to 6-16 fold & peak about 16 hrs before ovulationbefore ovulation . .

- -FSH also increases to 2 to 3 fold & acts synergistically FSH also increases to 2 to 3 fold & acts synergistically with LH to cause swelling of the follicle before with LH to cause swelling of the follicle before ovulationovulation . .

- -LH has specific effect on the granulosa cells & theca cells LH has specific effect on the granulosa cells & theca cells converting them to progesterone secreting cells so the converting them to progesterone secreting cells so the rate of estrogen secretion begins to fall about 1 day rate of estrogen secretion begins to fall about 1 day before ovulation while progesterone secretion begin to before ovulation while progesterone secretion begin to increaseincrease..

Initiation of ovulationInitiation of ovulation::

Large quantity of LHLarge quantity of LH secreted by the AP causes secreted by the AP causes rapid secretion of progesterone from the follicle rapid secretion of progesterone from the follicle few hours few hours & 2 events occur which are necessary & 2 events occur which are necessary for ovulationfor ovulation::

11 ) )the theca externa begins to secrete proteolytic the theca externa begins to secrete proteolytic enzymes & causes weakening of the wall result in enzymes & causes weakening of the wall result in swelling of the follicle & degeneration of the swelling of the follicle & degeneration of the stigmastigma;;

22 ) )rapid growth of new blood vessels into the follicle rapid growth of new blood vessels into the follicle wall & prostaglandins are secreted into the wall & prostaglandins are secreted into the follicular tissuefollicular tissue . .

--The two effects causes swelling of the follicle & The two effects causes swelling of the follicle & plasma transudation into the follicle & plasma transudation into the follicle & degeneration of the stigma with discharge of the degeneration of the stigma with discharge of the ovumovum..

Luteal phase of the ovarian cycleLuteal phase of the ovarian cycle::

- -After expulsion of the ovum from the follicle, the After expulsion of the ovum from the follicle, the remaining granulosa & theca internal cells change to remaining granulosa & theca internal cells change to lutein cells & become filled with lipid inclusions lutein cells & become filled with lipid inclusions giving them yellowish appearance. The granulosa giving them yellowish appearance. The granulosa cells with the theca cells called cells with the theca cells called corpus luteumcorpus luteum..

- -The granulosa cells in corpus luteum develop The granulosa cells in corpus luteum develop extensive intracellular endoplasmic reticula & form extensive intracellular endoplasmic reticula & form large amount of progesterone & estrogen. The theca large amount of progesterone & estrogen. The theca cells form mainly androgens which are converted by cells form mainly androgens which are converted by granulosa cells into female hormonesgranulosa cells into female hormones..

- -The corpus luteum grow to about 1.5 cm in diameter, The corpus luteum grow to about 1.5 cm in diameter, at about 7 to 8 days after ovulation .Then begins to at about 7 to 8 days after ovulation .Then begins to involute & losses its secretory function & its involute & losses its secretory function & its yellowish characteristic about 12 days after ovulation yellowish characteristic about 12 days after ovulation & becomes & becomes corpus albicanscorpus albicans & replaced by connective & replaced by connective tissue & absorbedtissue & absorbed..

Luteinizing function of LHLuteinizing function of LH::11 - -The change of granulosa or theca The change of granulosa or theca

interna cells into lutein cellsinterna cells into lutein cells..22 - -Extrusion of the ovum from the follicle Extrusion of the ovum from the follicle

Uncharacterized local hormone in the Uncharacterized local hormone in the follicular fluid called luteinization – follicular fluid called luteinization – inhibiting factor hold the luteinization inhibiting factor hold the luteinization process until after ovulationprocess until after ovulation..

33 - -Secretion of progesterone & estrogen Secretion of progesterone & estrogen from the corpus luteumfrom the corpus luteum..

- -If pregnancy occur, the chorionic If pregnancy occur, the chorionic gonadotropin from the placenta act on gonadotropin from the placenta act on the corpus luteum to prolong its life for the corpus luteum to prolong its life for 2 to 4 months of pregnancy2 to 4 months of pregnancy..

Involution of the corpus luteum and onset of Involution of the corpus luteum and onset of the next ovarian cyclethe next ovarian cycle::

11 - -Estrogen & progesterone secreted by the corpus Estrogen & progesterone secreted by the corpus luteum in luteal phase have strong negative luteum in luteal phase have strong negative feedback effect on AP to inhibit the secretion of FSH feedback effect on AP to inhibit the secretion of FSH & LH& LH..

22 - -The lutein cells secrete small amounts of inhibin The lutein cells secrete small amounts of inhibin which inhibit secretion of FSH by AP. Low levels of which inhibit secretion of FSH by AP. Low levels of both FSH & LH & loss of these hormones causes the both FSH & LH & loss of these hormones causes the corpus luteum to degenerate completely, called corpus luteum to degenerate completely, called involutioninvolution of the corpus luteum of the corpus luteum..

33 - -Around 26th days of normal sexual cycle & after Around 26th days of normal sexual cycle & after involution of corpus luteum, sudden cessation of involution of corpus luteum, sudden cessation of secretion of estrogen, progesterone & inhibin secretion of estrogen, progesterone & inhibin removes the feedback inhibition of the AP & allowing removes the feedback inhibition of the AP & allowing increase secretion of FSH & LH again. FSH & LH increase secretion of FSH & LH again. FSH & LH initiate the growth of new follicles, beginning a new initiate the growth of new follicles, beginning a new ovarian cycleovarian cycle..

Monthly endometrial cycle and menstruationMonthly endometrial cycle and menstruation::

Associated with monthly cyclical production of estrogens & Associated with monthly cyclical production of estrogens & progesterone by the ovaries the endometrial lining of progesterone by the ovaries the endometrial lining of the uterus pass the uterus pass through the following stagesthrough the following stages..

11 - -Proliferation phase (estrogen phase) of the endometrial Proliferation phase (estrogen phase) of the endometrial cycle, occurring before ovulationcycle, occurring before ovulation::

- -At the beginning of each cycle, most of the endometrium At the beginning of each cycle, most of the endometrium has been desquamated by menstruation. After has been desquamated by menstruation. After menstruation only thin layer of the endometrial stroma menstruation only thin layer of the endometrial stroma remains & the deeper portions of the glands &crypts of remains & the deeper portions of the glands &crypts of the endometrium under the influence of estrogens, the endometrium under the influence of estrogens, secreted in large quantities by the ovaries, the stromal secreted in large quantities by the ovaries, the stromal

cells & epithelial cells proliferate rapidlycells & epithelial cells proliferate rapidly . . - -The endometrial surface re-epitheliazed within 4-7 days The endometrial surface re-epitheliazed within 4-7 days

after the beginning of menstruation. Before ovulation after the beginning of menstruation. Before ovulation the endometrium thickness increase, due to increase the endometrium thickness increase, due to increase numbers of stromal cells &progressive growth of the numbers of stromal cells &progressive growth of the glands & new blood vesselsglands & new blood vessels . .

- -At the time of ovulation, the endometrium is 3-5 mm At the time of ovulation, the endometrium is 3-5 mm thick. The endometrial glands, cervical region secrete a thick. The endometrial glands, cervical region secrete a thin, stringy mucus which help to guide sperm in the thin, stringy mucus which help to guide sperm in the proper direction from the vagina into the uterusproper direction from the vagina into the uterus..

22 - -Secretory phase (progestational phase) of the Secretory phase (progestational phase) of the endometrial cycle, occurring after ovulationendometrial cycle, occurring after ovulation::

After ovulation, estrogen & progesterone are secreted in After ovulation, estrogen & progesterone are secreted in the later part of the monthly cycle by the corpus the later part of the monthly cycle by the corpus luteum. Estrogen cause slight proliferation in the luteum. Estrogen cause slight proliferation in the endometrium& progesterone causes marked swelling endometrium& progesterone causes marked swelling & secretory development of the endometrium. The & secretory development of the endometrium. The glands increase in tortuosity, excess secretory glands increase in tortuosity, excess secretory substances accumulates in the glandssubstances accumulates in the glands . .

- -Stromal cells cytoplasm increase lipid &glycogen Stromal cells cytoplasm increase lipid &glycogen deposits in the cells & blood supply to the deposits in the cells & blood supply to the endometrium increases and become more tortuous. 1 endometrium increases and become more tortuous. 1 week after ovulation, endometrium thickness is 5-6 week after ovulation, endometrium thickness is 5-6

mmmm . .

--The secretory changes prepared the endometrium (stored The secretory changes prepared the endometrium (stored nutrients) for implantation of the fertilized nutrients) for implantation of the fertilized ovum .Uterine secretions called “ovum .Uterine secretions called “uterine milkuterine milk” ” provide nutrition for the diving ovum. The provide nutrition for the diving ovum. The trophobastic cells on the surface of the implanted trophobastic cells on the surface of the implanted ovum begin to digest the endometrium & absorbed ovum begin to digest the endometrium & absorbed endometrial stored substancesendometrial stored substances..

MenstruationMenstruation::--If the ovum is not fertilized,If the ovum is not fertilized, about 2 days before the end about 2 days before the end

of the monthly cycle, the corpus luteum involutes & of the monthly cycle, the corpus luteum involutes & estrogens & progesterone decrease to low levels of estrogens & progesterone decrease to low levels of secretion. Due to decrease estrogen & progesterone at secretion. Due to decrease estrogen & progesterone at the end of the monthly cycle ,there is decrease the end of the monthly cycle ,there is decrease stimulation of the endometrium, followed by involution stimulation of the endometrium, followed by involution of the endometrium about 65% of its previous thicknessof the endometrium about 65% of its previous thickness..

- -During the 24 hrs preceding the menstruation, there is During the 24 hrs preceding the menstruation, there is vasospasm of the tortuous blood vessels & release of vasospasm of the tortuous blood vessels & release of vasoconstrictor prostaglandinsvasoconstrictor prostaglandins..There isThere is-; -;

11 ) )vasospasmvasospasm ; ;22 ) )decrease nutrients to the endometriumdecrease nutrients to the endometrium

33))loss of the hormonal stimulation, all initiate necrosis in loss of the hormonal stimulation, all initiate necrosis in the endometrium blood vessels. There is gradual the endometrium blood vessels. There is gradual necrosis of the outer layer of the endometrium separate necrosis of the outer layer of the endometrium separate from the uterus at the site of the hemorrhages within 48 from the uterus at the site of the hemorrhages within 48 hrs, all the superficial layers of the endometrium hrs, all the superficial layers of the endometrium desquamated in the uterine cavitydesquamated in the uterine cavity . .

- -The mass of desquamated tissue & blood plus the The mass of desquamated tissue & blood plus the contractile effects of prostaglandins all initiate contractile effects of prostaglandins all initiate contractions which expel the uterine contentscontractions which expel the uterine contents..

- -In normal menstruation, about 40 ml of In normal menstruation, about 40 ml of blood + 35 ml of serous fluid are lost. blood + 35 ml of serous fluid are lost. The menstrual blood is normally non-The menstrual blood is normally non-clotting due to the presence of clotting due to the presence of fibrinolysinfibrinolysin..

--Within 4 to 7 days after menstruation, the Within 4 to 7 days after menstruation, the loss of blood ceases & the endometrium loss of blood ceases & the endometrium become re-epithelializedbecome re-epithelialized..Leukorrhea during menstruationLeukorrhea during menstruation::During menstruation, leukocytes are During menstruation, leukocytes are released with the necrotic material & released with the necrotic material & blood so the uterus is highly resistant to blood so the uterus is highly resistant to infection during menstruation as infection during menstruation as protective mechanismprotective mechanism..

Regulation of the female monthly rhythm, Regulation of the female monthly rhythm, interplay between the ovarian and interplay between the ovarian and hypothalamic-pituitary hormoneshypothalamic-pituitary hormones::

- -Secretion of AP hormone is controlled by “Secretion of AP hormone is controlled by “releasing releasing hormoneshormones” formed in the hypothalamus and ” formed in the hypothalamus and transported to the AP gland by the hypothalamic-transported to the AP gland by the hypothalamic-hypophysial portal systemhypophysial portal system..

- -Intermittent, pulsatileIntermittent, pulsatile secretion of GnRH by the secretion of GnRH by the hypothalamus stimulates pulsatile release of LH from hypothalamus stimulates pulsatile release of LH from the APthe AP::GnRH is secreted in pulses lasting 5 to 25 minutes every GnRH is secreted in pulses lasting 5 to 25 minutes every 1 to 2 hrs. The pulsatile release of GnRH cause 1 to 2 hrs. The pulsatile release of GnRH cause intermittent output of LH secretion about every 90 intermittent output of LH secretion about every 90 minutesminutes..

Hypothalamic centers for release of GnRHHypothalamic centers for release of GnRH::The neural activity that causes pulsatile release of GnRH The neural activity that causes pulsatile release of GnRH occurs in the mediobasal hypothalamus, in the arcuate occurs in the mediobasal hypothalamus, in the arcuate nuclei regulate most of the female sexual activitynuclei regulate most of the female sexual activity..

Negative feedback effects of estrogen and Negative feedback effects of estrogen and progesterone in decreasing both LH and progesterone in decreasing both LH and FSH secretionFSH secretion::

- -Estrogen in small amounts has strong Estrogen in small amounts has strong effect to inhibit the production of LH & effect to inhibit the production of LH & FSH. This inhibitory effect of estrogen is FSH. This inhibitory effect of estrogen is increased when progesterone is increased when progesterone is available. This inhibitory effects more available. This inhibitory effects more on the AP directly & to lesser extent on on the AP directly & to lesser extent on the hypothalamus to inhibit the the hypothalamus to inhibit the secretion of GnRHsecretion of GnRH..Hormone inhibin from the corpus luteum Hormone inhibin from the corpus luteum inhibits FSH & LH secretioninhibits FSH & LH secretion::The hormone inhibin secreted by the The hormone inhibin secreted by the granulosa cells of the ovarian corpus granulosa cells of the ovarian corpus luteum inhibit the secretion of FSH & to luteum inhibit the secretion of FSH & to lesser extent LHlesser extent LH..

Positive feedback effect of estrogen before Positive feedback effect of estrogen before ovulation – the pre-ovulatory LH surgeovulation – the pre-ovulatory LH surge::

- -AP secretes increased amount of LH for 1 to 2 AP secretes increased amount of LH for 1 to 2 days beginning 24 to 48 hrs before ovulation. days beginning 24 to 48 hrs before ovulation. FSH surge is much smaller in the pre-FSH surge is much smaller in the pre-ovulatory than LH surgeovulatory than LH surge..

The possible causes of LH secretion could beThe possible causes of LH secretion could be::estrogen has special estrogen has special positive feedbackpositive feedback effect of effect of stimulating pituitary secretion of LH & to a stimulating pituitary secretion of LH & to a lesser extent FSHlesser extent FSHthe granulosa cells of the follicle begin to the granulosa cells of the follicle begin to secrete small increasing amount of secrete small increasing amount of progesterone about 1 day before ovulation progesterone about 1 day before ovulation which stimulate LH secretionwhich stimulate LH secretion

Feedback oscillation of the Feedback oscillation of the hypothalamic-pituitary-ovarian systemhypothalamic-pituitary-ovarian system::

Postovulatory secretion of the ovarian Postovulatory secretion of the ovarian hormones, and depression of the hormones, and depression of the pituitary gonadotropinspituitary gonadotropins::

During the postovulatory phase (between During the postovulatory phase (between ovulation & beginning of menstruation) the ovulation & beginning of menstruation) the corpus luteum secrete large quantities of corpus luteum secrete large quantities of both progesterone &estrogen & inhibin both progesterone &estrogen & inhibin which all together cause negative feedback which all together cause negative feedback effect on AP & hypothalamus to inhibit both effect on AP & hypothalamus to inhibit both FSH & LH secretion. (lowest level 3-4 days FSH & LH secretion. (lowest level 3-4 days before the onset of menstruation)before the onset of menstruation)

Follicular growth phaseFollicular growth phase-: -:

--22 to 3 days before menstruation, corpus luteum regress & to 3 days before menstruation, corpus luteum regress & secretion of estrogen, progesterone & inhibin decreasesecretion of estrogen, progesterone & inhibin decrease . .

--This decrease remove the negative feedback effect on AP This decrease remove the negative feedback effect on AP

hormones. Therefore a day after menstruation FSH hormones. Therefore a day after menstruation FSH secretion begins to increase (2 folds) while LH secretion begins to increase (2 folds) while LH secretion is slightly. These hormones causes growth of secretion is slightly. These hormones causes growth of the follicle. During the first 11 to 12 days of this the follicle. During the first 11 to 12 days of this follicle growth the rate of secretion of FSH & LH follicle growth the rate of secretion of FSH & LH decrease slightly because of the negative feedback decrease slightly because of the negative feedback effect of estrogen on the APeffect of estrogen on the AP..

Pre ovulatory surge of LH & FSH causes Pre ovulatory surge of LH & FSH causes ovulationovulation::

About 12 days of the monthly cycle, the high secretion of About 12 days of the monthly cycle, the high secretion of FSH & LH start to increase due to high level of FSH & LH start to increase due to high level of estrogens causes positive feedback on the anterior estrogens causes positive feedback on the anterior pituitary which leads to pre-ovulatory LH surge & FSH pituitary which leads to pre-ovulatory LH surge & FSH surgesurge..

Puberty and menarchePuberty and menarche::Puberty:Puberty: means the onset of adult sexual means the onset of adult sexual lifelife..MenarcheMenarche: means the beginning of the : means the beginning of the cycle of menstruationcycle of menstruation..Puberty is caused by a gradual increase in Puberty is caused by a gradual increase in gonadotropic hormonegonadotropic hormone secretion by AP in secretion by AP in about 8 years of life, the onset of puberty about 8 years of life, the onset of puberty & menstruation between 11 and 16 years & menstruation between 11 and 16 years in girls. The onset of puberty is initiated in girls. The onset of puberty is initiated by maturation in the brain in the limbic by maturation in the brain in the limbic systemsystem..

MenopauseMenopause::At the age of 40 to 50 years, the sexual cycle becomes At the age of 40 to 50 years, the sexual cycle becomes irregular, ovulation fails to occur &the cycle ceasesirregular, ovulation fails to occur &the cycle ceases..

Definition of menopauseDefinition of menopause::

- -The period during which the cycle ceases & the female The period during which the cycle ceases & the female sex hormones diminish to almost none. When sex hormones diminish to almost none. When estrogens production falls below the critical value, estrogens production falls below the critical value, estrogens no longer inhibit the production of estrogens no longer inhibit the production of gonadotropins FSH & LH. The production of FSH & gonadotropins FSH & LH. The production of FSH & LH after menopause in large amountLH after menopause in large amount..

The loss of estrogens causes marked physiological The loss of estrogens causes marked physiological changes in the function of the body includingchanges in the function of the body including::

11“ )“ )hot flushes” characterized by extreme flushing of the skinhot flushes” characterized by extreme flushing of the skin;; 22 ) )psychic sensations and dyspneapsychic sensations and dyspnea ; ;

33 ) )irritabilityirritability ; ;44 ) )fatiguefatigue;;

55 ) )anxietyanxiety;; 66 ) )occasionally various psychotic statesoccasionally various psychotic states

77 ) )decreased strength and calcification of bones throughout decreased strength and calcification of bones throughout the bodythe body..

Functions of the ovarian hormones – Functions of the ovarian hormones – estradiol & progesteroneestradiol & progesterone::

--Estrogens promote proliferation & growth of Estrogens promote proliferation & growth of specific cells in the body that are responsible for specific cells in the body that are responsible for the development of most secondary sexual the development of most secondary sexual characteristics of the femalecharacteristics of the female

--progesterone prepare the uterus for pregnancy & progesterone prepare the uterus for pregnancy & the breast for lactationthe breast for lactation..Chemistry of the sex hormonesChemistry of the sex hormones::Estrogens are secreted in significant amount by the Estrogens are secreted in significant amount by the ovaries & in small amount by the adrenal ovaries & in small amount by the adrenal corticescortices..These estrogens areThese estrogens are: B estradiol, estrone & estriol, : B estradiol, estrone & estriol, B estradiol is most potent estrogenB estradiol is most potent estrogen..

ProgestinsProgestins::Prosterone is the only important progestin. It is secreted in Prosterone is the only important progestin. It is secreted in significant amount by the corpus luteum &by the significant amount by the corpus luteum &by the placenta during pregnancy especially after the fourth placenta during pregnancy especially after the fourth month of gestationmonth of gestation..

Synthesis of estrogens and progestinsSynthesis of estrogens and progestins::They are synthesized in the ovaries mainly from cholesterol They are synthesized in the ovaries mainly from cholesterol & slightly from acetyl-coenzyme A& slightly from acetyl-coenzyme A..During the follicular phase, progesterone & testosterone During the follicular phase, progesterone & testosterone are synthesized & converted by the granulosa cells into are synthesized & converted by the granulosa cells into estrogensestrogens..

Estrogens & progesterone are transported in the blood Estrogens & progesterone are transported in the blood bound to plasma proteinsbound to plasma proteins::Both estrogens & progesterone are transported bound with Both estrogens & progesterone are transported bound with plasma albumin & with specific estrogen & progesterone-plasma albumin & with specific estrogen & progesterone-binding globulins & are released to the tissues for 30 binding globulins & are released to the tissues for 30 minutesminutes..

--estrogen degraded by the liver & excreted in the bile & estrogen degraded by the liver & excreted in the bile & urineurine . .

--Progesterone is degraded in the liver to metabolic Progesterone is degraded in the liver to metabolic degradation & excreted in urinedegradation & excreted in urine..

Functions of estrogens – their effects on Functions of estrogens – their effects on the primary and secondary female sex the primary and secondary female sex characteristicscharacteristics::

Estrogen cause cellular proliferation & growth of the Estrogen cause cellular proliferation & growth of the tissues of the sex organs &other tissues related to tissues of the sex organs &other tissues related to reproductionreproduction..

11 - -Effect of estrogens on the uterus & female sex organsEffect of estrogens on the uterus & female sex organs

– –At puberty estrogen secreted in large quantities under At puberty estrogen secreted in large quantities under the influence of GnRHs. Female sex organs change from the influence of GnRHs. Female sex organs change from

those of a child to those of an adultthose of a child to those of an adult . .--The ovaries, fallopian tubes, uterus and vagina all The ovaries, fallopian tubes, uterus and vagina all

increase in sizeincrease in size.. - -The external genitalia enlarge with deposition of fatThe external genitalia enlarge with deposition of fat . . - -Vaginal epithelium change from cuboidal to stratified Vaginal epithelium change from cuboidal to stratified

typetype . . - -The uterus increases in size (2 to 3 folds) with The uterus increases in size (2 to 3 folds) with

proliferation of the endometrial stroma & increased proliferation of the endometrial stroma & increased development of endometrial glandsdevelopment of endometrial glands..

22 - -Effect of estrogens on the fallopian tubesEffect of estrogens on the fallopian tubes– – it affects the mucosal lining of the fallopian tubes, causes it affects the mucosal lining of the fallopian tubes, causes

proliferation of the glandular lining tissues. The proliferation of the glandular lining tissues. The number of ciliated epithelial cells increase. These number of ciliated epithelial cells increase. These cilia beat towards the uterus which helps movement cilia beat towards the uterus which helps movement of the fertilized ovum in that directionof the fertilized ovum in that direction..

33 - -Effect of estrogens on the breastEffect of estrogens on the breast – – 11 ) )development of the stromal tissues of the breastsdevelopment of the stromal tissues of the breasts;;

22 ) )growth of the ductile system andgrowth of the ductile system and 33 ) )deposition of fat in the breastdeposition of fat in the breast

44 - -Effect of estrogens on the skeletonEffect of estrogens on the skeleton– – estrogens inhibit osteoclastic activity in the bones so it estrogens inhibit osteoclastic activity in the bones so it

stimulates bone growth. Also it causes union of the stimulates bone growth. Also it causes union of the epiphyses with the shafts of the long bones similar to epiphyses with the shafts of the long bones similar to testosterone but much stronger, testosterone but much stronger, in old age in women in old age in women after menopause due to deficiency of estrogen after menopause due to deficiency of estrogen secretion there issecretion there is

11 ) )increased osteoclast activityincreased osteoclast activity;; 22 ) )decreased bone matrixdecreased bone matrix

33 ) )decreased deposition of bone calcium and phosphate decreased deposition of bone calcium and phosphate which result to osteoporosiswhich result to osteoporosis..

55 - -Effect of estrogens on protein depositionEffect of estrogens on protein deposition – –estrogens cause slight increase in total body protein, which estrogens cause slight increase in total body protein, which

cause a slight positive nitrogen balancecause a slight positive nitrogen balance

66 - -Effect of estrogens on body metabolism and fat depositionEffect of estrogens on body metabolism and fat deposition – – estrogens cause a slight increase in the whole body estrogens cause a slight increase in the whole body

metabolic rate: also it cause deposition of fat in metabolic rate: also it cause deposition of fat in subcutaneous tissues. It causes deposition of fat in the subcutaneous tissues. It causes deposition of fat in the breasts, buttocks and thighs, which is characteristic of breasts, buttocks and thighs, which is characteristic of the feminine figurethe feminine figure

77 - -Effect of estrogens on hair distributionsEffect of estrogens on hair distributions – – estrogens don’t affect hair distribution. Hair develop in the estrogens don’t affect hair distribution. Hair develop in the

pubic region and in the axillae after pubertypubic region and in the axillae after puberty

88 - -Effect of estrogens on the skinEffect of estrogens on the skin – –it causes the skin to develop a texture that is soft and it causes the skin to develop a texture that is soft and

smooth and cause the skin to become more vascular smooth and cause the skin to become more vascular which leads to increased warmth of the skin and promotes which leads to increased warmth of the skin and promotes greater bleeding of the cut surfaces than in mengreater bleeding of the cut surfaces than in men

99--Effect of estrogens on electrolyte balanceEffect of estrogens on electrolyte balance – –it causes Na+ and water retention by the kidney tubulesit causes Na+ and water retention by the kidney tubules

Functions of progesteroneFunctions of progesterone::

11 - -Effect of progesterone on the uterusEffect of progesterone on the uterus

it promotes secretory changes in the uterine it promotes secretory changes in the uterine endometrium during the latter half of the monthly endometrium during the latter half of the monthly sexual cycle. The glands increase in tortuosity & sexual cycle. The glands increase in tortuosity & excess of secretory substances accumulates in the excess of secretory substances accumulates in the glandular epithelial cells. There is increase deposition glandular epithelial cells. There is increase deposition of lipid & glycogen in the cytoplasm of the stromal of lipid & glycogen in the cytoplasm of the stromal cells & the blood supply to endometrium increases & cells & the blood supply to endometrium increases & become more highly tortuous. Thus preparing the become more highly tortuous. Thus preparing the uterus for the implantation of the fertilized ovumuterus for the implantation of the fertilized ovum

22 - -Effect of progesterone on the fallopian tubesEffect of progesterone on the fallopian tubes

– –it promotes increased secretion by the mucosal lining of it promotes increased secretion by the mucosal lining of the fallopian tubes which are necessary for nutrition of the fallopian tubes which are necessary for nutrition of the fertilized dividing ovum as it transverses the the fertilized dividing ovum as it transverses the fallopian tube before implantationfallopian tube before implantation

33 - -Effect of progesterone on the breastsEffect of progesterone on the breasts

– –it promote development of the it promote development of the lobules and alveolilobules and alveoli of the of the breasts, causing the alveolar cells to proliferate, breasts, causing the alveolar cells to proliferate, enlarge, and become secretory in nature. Also it enlarge, and become secretory in nature. Also it causes the breasts to swell (due to secretory causes the breasts to swell (due to secretory development in the lobules and alveoli, and also due to development in the lobules and alveoli, and also due to increase fluid in the subcutaneous tissue)increase fluid in the subcutaneous tissue)..

Abnormalities of secretion by the ovariesAbnormalities of secretion by the ovaries::

11--HypogonadismHypogonadism::When the ovaries are absent from birth or they are non-When the ovaries are absent from birth or they are non-functional before puberty, female functional before puberty, female eunuchismeunuchism occurs. occurs. Sexual organs remain infantile& the secondary sexual Sexual organs remain infantile& the secondary sexual characteristics do not appear. Female eunuch is tall characteristics do not appear. Female eunuch is tall because of delay closure of the epiphyses of the long because of delay closure of the epiphyses of the long bonesbones..

22 - -Irregularity of menses& amenorrhea caused by Irregularity of menses& amenorrhea caused by hypogonadismhypogonadism::In hypogonadism or when the gonads secrete small In hypogonadism or when the gonads secrete small quantities of estrogens such as hypothyroidism, the quantities of estrogens such as hypothyroidism, the ovarian cycle does not occur normally, menstruation ovarian cycle does not occur normally, menstruation may stop (amenorrhea). Prolonged ovarian cycle are may stop (amenorrhea). Prolonged ovarian cycle are associated with failure of ovulation because of associated with failure of ovulation because of insufficient secretion of LHinsufficient secretion of LH..

33 - -Hypersecretion by the ovariesHypersecretion by the ovaries::Rare and only recognized when feminizing tumor Rare and only recognized when feminizing tumor develops. A rare granulosa cell tumor develop after develops. A rare granulosa cell tumor develop after menopause and secrete large quantities of estrogens, menopause and secrete large quantities of estrogens, causing irregular bleeding from the endometriumcausing irregular bleeding from the endometrium..

Female fertilityFemale fertility::

Fertile period of each sexual cycleFertile period of each sexual cycle::Once the ovum is expelled from the ovary, it remains Once the ovum is expelled from the ovary, it remains capable of being fertilized no longer than 24 hours. capable of being fertilized no longer than 24 hours. Therefore for fertilization, Therefore for fertilization, intercourse must occur 4-intercourse must occur 4-5 days5 days before ovulation up to a few hours after before ovulation up to a few hours after ovulationovulation..

Rhythm method of contraceptionRhythm method of contraception::Avoidance of intercourse for 4 days before the Avoidance of intercourse for 4 days before the calculated day of ovulation and 3 days after ovulation calculated day of ovulation and 3 days after ovulation prevents conception (in regular cycle)prevents conception (in regular cycle)..Hormonal suppression of fertility “the pillHormonal suppression of fertility “the pill””

Administration of appropriate quantities of either Administration of appropriate quantities of either estrogen or progesterone during the 1st half of the estrogen or progesterone during the 1st half of the monthly cycle can inhibit ovulation. Because these monthly cycle can inhibit ovulation. Because these hormones prevent preovulatory surge of LH secretion hormones prevent preovulatory surge of LH secretion by anterior pituitary which is essential for ovulation by anterior pituitary which is essential for ovulation (old concept)(old concept)..

Oral contraceptive:-Oral contraceptive:- contains synthetic contains synthetic progestin in place of progesterone along progestin in place of progesterone along with small amounts of estrogen to with small amounts of estrogen to prevent ovulationprevent ovulation

( ( aa ) )to prevent the unwanted effect of natural to prevent the unwanted effect of natural estrogen & progesteroneestrogen & progesterone. .

((bb ) )the natural hormones may destroy the liverthe natural hormones may destroy the liver..They are used at the beginning of the They are used at the beginning of the monthly cycle & continued beyond time monthly cycle & continued beyond time of ovulation & stopped before of ovulation & stopped before menstruation to allow new cycle to menstruation to allow new cycle to begin (new concept)begin (new concept)..

Abnormal conditions: the cause of female sterilityAbnormal conditions: the cause of female sterility::11 - -failure to ovulate due to hyposecretion of gonadotropic failure to ovulate due to hyposecretion of gonadotropic

hormone, treated by hormone, treated by HCG hormone(HCG hormone( it has LH it has LH effect),or due to abnormal ovaries that cannot ovulate effect),or due to abnormal ovaries that cannot ovulate as in case of thick ovarian capsule. In this anovulatory as in case of thick ovarian capsule. In this anovulatory cycle in sterile women the normal increase in cycle in sterile women the normal increase in progesterone secretion doesn’t occur in the latter half progesterone secretion doesn’t occur in the latter half of the cycleof the cycle . .

22 - -EndometriosisEndometriosis :- endometrial tissue grows :- endometrial tissue grows

&menstruate in the pelvic cavity surround the uterus, &menstruate in the pelvic cavity surround the uterus, fallopian tubes & ovaries, it causes fibrosis in the fallopian tubes & ovaries, it causes fibrosis in the pelvis, so it prevent the ovum to be released in the pelvis, so it prevent the ovum to be released in the abdominal cavity or it can occlude the fallopian tubesabdominal cavity or it can occlude the fallopian tubes..

33--SalpingitisSalpingitis –inflammation of the fallopian tubes that –inflammation of the fallopian tubes that cause fibrosis & occlude the tubescause fibrosis & occlude the tubes..

44--Secretion of abnormal mucous by uterine cervixSecretion of abnormal mucous by uterine cervix,, normally at the time of ovulation estrogen cause normally at the time of ovulation estrogen cause secretion of mucous that allow rapid motility of the secretion of mucous that allow rapid motility of the sperm into the uterus. So abnormalities of the cervix sperm into the uterus. So abnormalities of the cervix as infection or abnormal hormonal stimulation lead to as infection or abnormal hormonal stimulation lead to a viscous mucous plug that prevent fertilizationa viscous mucous plug that prevent fertilization . .

The test for progesterone isThe test for progesterone is::

- -Urine analysis for surge in pregnandiol the end Urine analysis for surge in pregnandiol the end product of progesterone (in the latter half of the product of progesterone (in the latter half of the cycle)cycle)..

- -The woman should chart her body temperature The woman should chart her body temperature throughout the cycle. Progesterone raised the body throughout the cycle. Progesterone raised the body temperature half degree during the latter half of the temperature half degree during the latter half of the cycle and the temperature rise abruptly at the time of cycle and the temperature rise abruptly at the time of ovulationovulation..

Pregnancy and LactationPregnancy and Lactation

Maturation and fertilization of the ovumMaturation and fertilization of the ovum::

In the ovary, the primary oocyte before it is released from In the ovary, the primary oocyte before it is released from the ovarian follicle, it divides by meiosis & it becomes the ovarian follicle, it divides by meiosis & it becomes the secondary oocyte & the first polar body is formed the secondary oocyte & the first polar body is formed (contain 23 chromosomes) & 23 unpaired chromosomes (contain 23 chromosomes) & 23 unpaired chromosomes in the secondary oocyte. The secondary oocyte is in the secondary oocyte. The secondary oocyte is ovulated into the abdominal cavity & enters the ovulated into the abdominal cavity & enters the fimbriated end of the fallopian tubefimbriated end of the fallopian tube..

Entry of the ovum into the fallopian tubeEntry of the ovum into the fallopian tube::

After ovulation occurs, the ovum with the granulosa cells After ovulation occurs, the ovum with the granulosa cells (the corona radiata) is expelled into the peritoneal (the corona radiata) is expelled into the peritoneal cavity & enter the fallopian tube to reach the uterine cavity & enter the fallopian tube to reach the uterine cavity. The fimbriated ends of each fallopian fall around cavity. The fimbriated ends of each fallopian fall around the ovaries. The inner surface of the fimbriated ends the ovaries. The inner surface of the fimbriated ends are lined with ciliated epithelium, the cilia are activated are lined with ciliated epithelium, the cilia are activated by estrogen, which causes them to beat toward the by estrogen, which causes them to beat toward the opening, or ostium, of the involved fallopian tube. Also, opening, or ostium, of the involved fallopian tube. Also, slow fluid current flowing toward the ostiumslow fluid current flowing toward the ostium..

Fertilization of the ovumFertilization of the ovum::

After ejaculation of semen into the vagina .Within 5 to 10 After ejaculation of semen into the vagina .Within 5 to 10 minutes a few sperm reach the ampulae of the fallopian minutes a few sperm reach the ampulae of the fallopian

tubestubes . .

This transport of the sperm is aided byThis transport of the sperm is aided by::11--contractions of the uterus & fallopian tubes stimulated by contractions of the uterus & fallopian tubes stimulated by

prostaglandins in the male seminal fluidprostaglandins in the male seminal fluid22--oxytocin released from the posterior pituitary gland of the oxytocin released from the posterior pituitary gland of the

female during her orgasmfemale during her orgasm

--Fertilization of the ovum takes place in the ampulla after Fertilization of the ovum takes place in the ampulla after sperm & ovum enter the ampulla. The sperm must penetrate sperm & ovum enter the ampulla. The sperm must penetrate the corona radiate & then penetrate the zona pellicidathe corona radiate & then penetrate the zona pellicida..

--Once the sperm entered the ovum, the secondary oocyte divides Once the sperm entered the ovum, the secondary oocyte divides to form mature ovum puls a second polar body is expelled. to form mature ovum puls a second polar body is expelled. The mature ovum, called the female pronucleus contain 23 The mature ovum, called the female pronucleus contain 23 chromosomes, known as the X chromosomechromosomes, known as the X chromosome..

--The fertilized ovum contain 23 unpaired chromosomes of the The fertilized ovum contain 23 unpaired chromosomes of the male pronucleus and the 23 unpaired chromosomes of the male pronucleus and the 23 unpaired chromosomes of the female pronucleusfemale pronucleus..

What determine the sex of the fetus:What determine the sex of the fetus:

After formation of mature sperm, half of these After formation of mature sperm, half of these carry an X chromosome (the female carry an X chromosome (the female chromosome) & half carry a Y chromosome chromosome) & half carry a Y chromosome (the male chromosome). If an X chromosome (the male chromosome). If an X chromosome from a sperm combines with an X chromosome from a sperm combines with an X chromosome from the ovum, gives a combination XX from the ovum, gives a combination XX (female child). But if Y chromosome from a (female child). But if Y chromosome from a sperm is paired with an X chromosome from sperm is paired with an X chromosome from the ovum gives a combination of XY (male the ovum gives a combination of XY (male child)child)..

Transport of the fertilized ovum in the Transport of the fertilized ovum in the fallopian tube:fallopian tube:

After fertilization, additional 3-5 days required for After fertilization, additional 3-5 days required for transport of the fertilized ovum through the fallopian transport of the fertilized ovum through the fallopian tube into the uterine cavity. tube into the uterine cavity. This transport is This transport is affected by:affected by:1-Fluid current in the tube from epithelial secretion1-Fluid current in the tube from epithelial secretion2-Movement of the ciliated epithelium that lines the 2-Movement of the ciliated epithelium that lines the tube, beat toward the uterustube, beat toward the uterus3-Weak contractions of the fallopian tube also aid the 3-Weak contractions of the fallopian tube also aid the ovum passageovum passage4-The fallopian tube remains spastically contracted for 4-The fallopian tube remains spastically contracted for the first 3 days after ovulation. Progesterone is the first 3 days after ovulation. Progesterone is secreted from the corpus luteum causes relaxation of secreted from the corpus luteum causes relaxation of the tube which allows entry of the ovum into the uterus. the tube which allows entry of the ovum into the uterus. -During transport of the fertilized ovum through the -During transport of the fertilized ovum through the fallopian tube, the fallopian tubes produce large fallopian tube, the fallopian tubes produce large quantities of secretions used for nutrition of the quantities of secretions used for nutrition of the developing blastocystdeveloping blastocyst

Implantation of the blastocyst in the uterus:Implantation of the blastocyst in the uterus:

-After the blastocyst reaches the uterus, it remains -After the blastocyst reaches the uterus, it remains for 1 to 3 days before it implants in the for 1 to 3 days before it implants in the endometrium. Implantation occurs on about 5th to endometrium. Implantation occurs on about 5th to 7th day after ovulation. Before implantation the 7th day after ovulation. Before implantation the blastocyst obtains its nutrition from endometrial blastocyst obtains its nutrition from endometrial secretions called “secretions called “uterine milk”uterine milk”

-Implantation results from the action of trophoblast -Implantation results from the action of trophoblast cells over the surface of the blastocyst, which cells over the surface of the blastocyst, which secrete proteolytic enzymes that digest the adjacent secrete proteolytic enzymes that digest the adjacent endometrial uterine cells. Fluids & nutrients are endometrial uterine cells. Fluids & nutrients are transported by the trophoblast cells into the transported by the trophoblast cells into the blastocyst. blastocyst. The trophoblast cells & other adjacent cells (from The trophoblast cells & other adjacent cells (from

the blastocyst & thethe blastocyst & the uterine endometrium) uterine endometrium)

proliferate forming the placenta & various proliferate forming the placenta & various membranes of pregnancy.membranes of pregnancy.

Early nutrition of the embryo:Early nutrition of the embryo:

During the latter half of the cycle, progesterone is During the latter half of the cycle, progesterone is secreted by the corpus luteum & converts the secreted by the corpus luteum & converts the stromal cells of the endometrium into swollen cells stromal cells of the endometrium into swollen cells containing extra amounts of glycogen, lipid, proteins containing extra amounts of glycogen, lipid, proteins and mineral necessary for development of the and mineral necessary for development of the conceptus. When the conceptus implanted in the conceptus. When the conceptus implanted in the endometrium, the continued secretion of endometrium, the continued secretion of progesterone causes endometrial cells to swell and progesterone causes endometrial cells to swell and store more nutrients & are store more nutrients & are called decidual cellscalled decidual cells. . The trophoblast cells invade the decidua, digesting The trophoblast cells invade the decidua, digesting it, the stored nutrients in the decidua are used by it, the stored nutrients in the decidua are used by the growing embryo. This continues for 8 weeks, the growing embryo. This continues for 8 weeks, then the placenta begins to provide nutrition after then the placenta begins to provide nutrition after about 16th day beyond fertilization.about 16th day beyond fertilization.

Placental permeability and membrane Placental permeability and membrane diffusion conductance:diffusion conductance:

-The major function of the placenta is to -The major function of the placenta is to provide for diffusion of food stuffs & oxygen provide for diffusion of food stuffs & oxygen from the mothers blood into the fetus blood & from the mothers blood into the fetus blood & diffusion of excretory products from the fetus diffusion of excretory products from the fetus back into the mother.back into the mother.

-In the early months of pregnancy, the -In the early months of pregnancy, the placenta is not fully developed & its placenta is not fully developed & its permeability is low, their diffusion is low.permeability is low, their diffusion is low.

-In later pregnancy, the permeability increase -In later pregnancy, the permeability increase because of thinning of the membrane & more because of thinning of the membrane & more surface area for diffusionsurface area for diffusion

Diffusion of oxygen through the placental Diffusion of oxygen through the placental membrane:membrane:The dissolved oxygen passes into the foetal blood by The dissolved oxygen passes into the foetal blood by simple simple diffusiondiffusion from the maternal sinuses. from the maternal sinuses. - The mean PO2 of the mothers blood in placental sinuses is - The mean PO2 of the mothers blood in placental sinuses is about about 50 mmHg50 mmHg, the mean PO2 in the fetal blood is , the mean PO2 in the fetal blood is about 30 about 30 mmHgmmHg. The mean pressure gradient for diffusion of oxygen . The mean pressure gradient for diffusion of oxygen through the placental membrane is about 20 mmHg.through the placental membrane is about 20 mmHg.There are three reasons why this low PO2 capable of There are three reasons why this low PO2 capable of allowing the foetal blood to transport oxygen to the allowing the foetal blood to transport oxygen to the fetal tissues as is transported by the mother’s blood to fetal tissues as is transported by the mother’s blood to be tissues.be tissues.1- Fetal hemoglobin (in O2 dissociation curve, the fetal 1- Fetal hemoglobin (in O2 dissociation curve, the fetal hemoglobin is shifted to the left). At low PO2 the fetal hemoglobin is shifted to the left). At low PO2 the fetal hemoglobin can carry more oxygen (20 to 50%) than maternal hemoglobin can carry more oxygen (20 to 50%) than maternal hemoglobin.hemoglobin.2- Hemoglobin concentration of fetal blood is about 50% 2- Hemoglobin concentration of fetal blood is about 50% greater than that of the mother which is important in greater than that of the mother which is important in enhancing the amount of oxygen transported to the fetal enhancing the amount of oxygen transported to the fetal tissues.tissues.3- Bohr effect at low PCO2, hemoglobin can carry more 3- Bohr effect at low PCO2, hemoglobin can carry more oxygen than it can at a high PCO2. The fetal blood entering oxygen than it can at a high PCO2. The fetal blood entering the placenta carries large amount of CO2 which diffuses into the placenta carries large amount of CO2 which diffuses into the maternal blood making her blood more acidic and fetal the maternal blood making her blood more acidic and fetal blood more alkaline. These changes increase the capacity of blood more alkaline. These changes increase the capacity of the fetal blood to combine with oxygen & decrease the the fetal blood to combine with oxygen & decrease the capacity of the maternal bloodcapacity of the maternal blood..

Diffusion of CO2 through the placental Diffusion of CO2 through the placental membrane:membrane:

The PCO2 of the fetal blood is The PCO2 of the fetal blood is 2 to 3 mmHg2 to 3 mmHg higher than higher than that of the maternal blood. So CO2 diffuses by this that of the maternal blood. So CO2 diffuses by this small pressure gradient into the maternal blood. CO2 small pressure gradient into the maternal blood. CO2 is highly soluble in the blood so it diffuses about 20 is highly soluble in the blood so it diffuses about 20 times more rapidly than oxygen.times more rapidly than oxygen.Diffusion of food stuffs through the placental Diffusion of food stuffs through the placental membrane:membrane:Most of the metabolic substrates needed by the fetus Most of the metabolic substrates needed by the fetus diffuse by diffuse by simple diffusionsimple diffusion into the fetal blood. into the fetal blood. --GlucoseGlucose is transported by is transported by facilitated diffusionfacilitated diffusion. The . The fetus uses as much glucose as the entire body of the fetus uses as much glucose as the entire body of the mother uses. Glucose level in the fetal blood is 20 to mother uses. Glucose level in the fetal blood is 20 to 30% lower than that in maternal blood.30% lower than that in maternal blood.-Fatty acids is highly soluble in cell membrane, so it -Fatty acids is highly soluble in cell membrane, so it diffuses from the maternal blood into fetal blood, but diffuses from the maternal blood into fetal blood, but more slowly than glucose. Also ketone bodies, K+, Na+ more slowly than glucose. Also ketone bodies, K+, Na+ and Cl- ions diffuse easily from the mother to the fetus.and Cl- ions diffuse easily from the mother to the fetus.Excretion of waste products through the placental Excretion of waste products through the placental membrane:membrane:Other excretory products (similar to CO2) also diffuse Other excretory products (similar to CO2) also diffuse from the fetus through the placental membrane into from the fetus through the placental membrane into the maternal blood to be excreted with the excretory the maternal blood to be excreted with the excretory products of the mother. products of the mother. These include non-protein These include non-protein nitrogens such as urea, uric acid, & creatinine (by nitrogens such as urea, uric acid, & creatinine (by diffusion gradient)diffusion gradient)..

Hormonal factors in pregnancy:Hormonal factors in pregnancy:

-The placenta forms large quantities of HCG, estrogens, -The placenta forms large quantities of HCG, estrogens, progesterone & human chorionic somatomammotropin progesterone & human chorionic somatomammotropin which are essential for normal pregnancy.which are essential for normal pregnancy.

Functions of the human chorionic Functions of the human chorionic gonadotropin:gonadotropin:-The secretion of this hormone begin 8 to 9 days after -The secretion of this hormone begin 8 to 9 days after ovulation after implantation & reach a maximum levels ovulation after implantation & reach a maximum levels at about 10 to 12 weeks of pregnancy & decreases back at about 10 to 12 weeks of pregnancy & decreases back to a lower value by 16 to 20 weeks.to a lower value by 16 to 20 weeks.

1- It prevents involution of the corpus luteum at the 1- It prevents involution of the corpus luteum at the end of the monthly cycle.end of the monthly cycle.2- It causes the corpus luteum to secrete large 2- It causes the corpus luteum to secrete large quantities of progesterone and estrogens.quantities of progesterone and estrogens.3- HCG stimulate the fetal testis (interstitial leydig cell) 3- HCG stimulate the fetal testis (interstitial leydig cell) to secrete testosterone which causes the fetus to grow to secrete testosterone which causes the fetus to grow male sex organs & causes the testis to descend into the male sex organs & causes the testis to descend into the scrotumscrotum..

Secretion of estrogens by the placenta:Secretion of estrogens by the placenta:The placenta secretes large amounts of estrogens & The placenta secretes large amounts of estrogens & progesterone (like the corpus luteum). Estrogens are progesterone (like the corpus luteum). Estrogens are formed from androgenic compounds which are formed formed from androgenic compounds which are formed in the adrenal glands of the mother & the fetus & in the adrenal glands of the mother & the fetus & converted by the trophoblast cells into estradiol.converted by the trophoblast cells into estradiol.

Function of estrogens in pregnancy:Function of estrogens in pregnancy:Proliferative function on most reproductive & Proliferative function on most reproductive & associated organs of the mother.associated organs of the mother.1-Enlargement of the mother’s uterus.1-Enlargement of the mother’s uterus.2-Enlargement of the mother’s breasts & growth of the 2-Enlargement of the mother’s breasts & growth of the breast ductal structures.breast ductal structures.3-Enlargement of the mother’s female external 3-Enlargement of the mother’s female external genitalia.genitalia.4-It relaxes the pelvic ligaments of the mother 4-It relaxes the pelvic ligaments of the mother (sacroiliac joints & symphysis pubis) which allow easier (sacroiliac joints & symphysis pubis) which allow easier passage of the fetus through the birth canalpassage of the fetus through the birth canal..

Secretion of progesterone by the Secretion of progesterone by the placenta:placenta:Progesterone is also essential for pregnancy, Progesterone is also essential for pregnancy, it is secreted in moderate quantities by the it is secreted in moderate quantities by the corpus luteumcorpus luteum at the beginning of pregnancy, at the beginning of pregnancy, later it is secreted in large quantities by the later it is secreted in large quantities by the placentaplacenta..Its effects that are essential for normal Its effects that are essential for normal pregnancy are:pregnancy are:1-It causes the decidual cells to develop in the 1-It causes the decidual cells to develop in the uterine endometrium which play an important uterine endometrium which play an important role in the nutrition of the early embryo.role in the nutrition of the early embryo.2-It decreases the contractility of the pregnant 2-It decreases the contractility of the pregnant uterus, thus preventing abortion.uterus, thus preventing abortion.3-It contributes to the development of the 3-It contributes to the development of the conceptus even before implantation, because conceptus even before implantation, because it increases the secretion of the mother’s it increases the secretion of the mother’s fallopian tubes & uterus to provide nutrients fallopian tubes & uterus to provide nutrients for the developing morula & blastocyst.for the developing morula & blastocyst.4-The progesterone secreted during 4-The progesterone secreted during pregnancy helps to prepare the mother’s pregnancy helps to prepare the mother’s breasts for lactation along with estrogenbreasts for lactation along with estrogen..

Human chorionic somatomammotropin:Human chorionic somatomammotropin:

The placenta begins to secrete this hormone at about The placenta begins to secrete this hormone at about the 5th week of pregnancy. It is secretion is continued the 5th week of pregnancy. It is secretion is continued by the placenta throughout the pregnancy & is by the placenta throughout the pregnancy & is increased in proportion to the weight of the placenta.increased in proportion to the weight of the placenta.

Its important effects include:Its important effects include:1- In lower animals it causes partial development of the 1- In lower animals it causes partial development of the animal’s breasts & causes lactation so it was first animal’s breasts & causes lactation so it was first named named human placental lactogenhuman placental lactogen (but not in human). (but not in human).

2- It has weak actions similar to the growth hormone 2- It has weak actions similar to the growth hormone causing formation of protein tissues but much weaker causing formation of protein tissues but much weaker than GH.than GH.

3-It causes decreased insulin sensitivity & decreased 3-It causes decreased insulin sensitivity & decreased glucose utilization by the mother making more glucose glucose utilization by the mother making more glucose available to the fetus (increased the fetus growth).available to the fetus (increased the fetus growth).

4-It promotes the release of free fatty acids from the fat 4-It promotes the release of free fatty acids from the fat stores of the mother, providing alternative source of stores of the mother, providing alternative source of energy for the mother’s metabolism during pregnancyenergy for the mother’s metabolism during pregnancy..

Other hormonal factors in pregnancy:Other hormonal factors in pregnancy:Almost all the non-sexual endocrine glands of the mother Almost all the non-sexual endocrine glands of the mother react with pregnancy. This result from the increased react with pregnancy. This result from the increased metabolic load on the mother &from the placental hormones metabolic load on the mother &from the placental hormones on the endocrine glands.on the endocrine glands.

1- Pituitary secretion:1- Pituitary secretion:The anterior pituitary gland enlarges (50%) & increases its The anterior pituitary gland enlarges (50%) & increases its production of corticotropin, thyrotropin & prolactin. production of corticotropin, thyrotropin & prolactin. Conversely, its secretion of FSH and LH is almost totally Conversely, its secretion of FSH and LH is almost totally suppressed suppressed as a result of the inhibitory effects of estrogens & as a result of the inhibitory effects of estrogens & progesterone from the placenta.progesterone from the placenta.

2-Corticosteroid secretion:2-Corticosteroid secretion:-The adrenocortical secretion of glucocorticoids is moderately -The adrenocortical secretion of glucocorticoids is moderately increased throughout pregnancy. These glucocorticoids help increased throughout pregnancy. These glucocorticoids help to mobilize amino acids from the mother’s tissues to be used to mobilize amino acids from the mother’s tissues to be used for synthesis of fetal tissues. for synthesis of fetal tissues. -Aldosterone secretion is increased (2 fold) reaching a peak at -Aldosterone secretion is increased (2 fold) reaching a peak at the end of gestation for reabsorption of excess Na+ from the the end of gestation for reabsorption of excess Na+ from the renal tubules leading to pregnancy-induced hypertensionrenal tubules leading to pregnancy-induced hypertension..

33--Secretion by the thyroid gland:Secretion by the thyroid gland:The mother’s thyroid gland enlarges up to 50% with The mother’s thyroid gland enlarges up to 50% with increases of its production of thyroxine. The increased increases of its production of thyroxine. The increased thyroxin production is caused by thyrotropic effect of thyroxin production is caused by thyrotropic effect of human chorionic gonadotropin secreted by the placenta human chorionic gonadotropin secreted by the placenta & by the thyroid stimulating hormones (human & by the thyroid stimulating hormones (human chorionic thyrotropin ) secreted by the placenta.chorionic thyrotropin ) secreted by the placenta.4-4-Secretion by the parathyroid glands:Secretion by the parathyroid glands:The parathyroid gland enlarge during pregnancy if the The parathyroid gland enlarge during pregnancy if the mother is on calcium deficient diet. Enlargement of mother is on calcium deficient diet. Enlargement of these glands causes Ca2+ absorption from the mother’s these glands causes Ca2+ absorption from the mother’s bones to maintain normal Ca2+ in the extracellular bones to maintain normal Ca2+ in the extracellular fluids of the mothers so the fetus removes Ca2+ to fluids of the mothers so the fetus removes Ca2+ to ossify its own bones. This effect increase during ossify its own bones. This effect increase during lactation because growing body requires more Ca2+ lactation because growing body requires more Ca2+ than the fetus.than the fetus.5-Secretion of “relaxin” by the ovaries and 5-Secretion of “relaxin” by the ovaries and placenta:placenta:The hormone called The hormone called “relaxin“relaxin” is secreted by the corpus ” is secreted by the corpus luteum & by the placental tissues. luteum & by the placental tissues. Its effect:Its effect:1- it causes relaxation of the ligaments of the symphysis 1- it causes relaxation of the ligaments of the symphysis pubis in animals. This effect is weak or absent in pubis in animals. This effect is weak or absent in pregnant women. This role mainly played by the pregnant women. This role mainly played by the estrogens which cause also relaxation of the pelvic estrogens which cause also relaxation of the pelvic ligamentsligamentsit softens the cervix of the pregnant women at the time it softens the cervix of the pregnant women at the time of deliveryof delivery -2 -2

Parturition:Parturition:

Increased uterine excitability near term. Parturition Increased uterine excitability near term. Parturition means birth of the baby. Towards the end of means birth of the baby. Towards the end of pregnancy, the uterus becomes more excitable, finally it pregnancy, the uterus becomes more excitable, finally it develops strong rhythmical contractions that the baby develops strong rhythmical contractions that the baby is expelledis expelled. There are two major effects leads to the . There are two major effects leads to the intense contractions responsible for parturition:intense contractions responsible for parturition:1- Progressive hormonal changes that cause increased 1- Progressive hormonal changes that cause increased excitability of the uterine musculatureexcitability of the uterine musculature2- Progressive mechanical changes2- Progressive mechanical changes

Hormonal factors that increases uterine Hormonal factors that increases uterine contractility:contractility:

Increased ratio of estrogen to progesterone:Increased ratio of estrogen to progesterone: 1-progesterone inhibits uterine contractility during 1-progesterone inhibits uterine contractility during pregnancy so that it help to prevent expulsion of the pregnancy so that it help to prevent expulsion of the fetus fetus

2– conversely, estrogens have a tendency to increase 2– conversely, estrogens have a tendency to increase the uterine contractility, partly because estrogens the uterine contractility, partly because estrogens increase the number of gap junctions between the increase the number of gap junctions between the adjacent uterine smooth muscle cell. adjacent uterine smooth muscle cell.

-Both estrogens & progesterone are secreted in -Both estrogens & progesterone are secreted in progressively greater quantities throughout pregnancy, progressively greater quantities throughout pregnancy, but from the 7th month onward, estrogen secretion but from the 7th month onward, estrogen secretion continue to increase while progesterone secretion continue to increase while progesterone secretion remains constant or decreases slightly. remains constant or decreases slightly.

- Towards the end of pregnancy estrogen/progesterone - Towards the end of pregnancy estrogen/progesterone ratio increases leading to increase uterine contractilityratio increases leading to increase uterine contractility..

Effect of oxytocin on the uterus:Effect of oxytocin on the uterus: oxytocin is a hormone secreted by the oxytocin is a hormone secreted by the neurohypophysis causes uterine contraction. neurohypophysis causes uterine contraction. Oxytocin increases uterine contractilityOxytocin increases uterine contractility near near term due to:term due to:

1-The uterine muscle increases its oxytocin 1-The uterine muscle increases its oxytocin receptors leading to increase its receptors leading to increase its responsiveness.responsiveness.2-The rate of oxytocin secretion by 2-The rate of oxytocin secretion by neurohypophysis is increased at the time of neurohypophysis is increased at the time of labor.labor.3-Irritation or stretching of the uterine cervix 3-Irritation or stretching of the uterine cervix as in labor, can cause neurogenic reflex as in labor, can cause neurogenic reflex through the paraventricular & supraoptic through the paraventricular & supraoptic nuclei of the hypothalamus that causes the nuclei of the hypothalamus that causes the posterior pituitary to secrete oxytocin posterior pituitary to secrete oxytocin (experiments in animals).(experiments in animals).4-Hypophysectomized animals can deliver 4-Hypophysectomized animals can deliver their young at term but labor is prolongedtheir young at term but labor is prolonged..

Effect of fetal hormone on the uterusEffect of fetal hormone on the uterus::

1- Fetus pituitary gland secrete increasing 1- Fetus pituitary gland secrete increasing quantities of quantities of oxytocinoxytocin which causes increase which causes increase uterine excitability.uterine excitability.

2-Fetus adrenal glands secrete large 2-Fetus adrenal glands secrete large quantities of quantities of cortisolcortisol, (uterine stimulant)., (uterine stimulant).

3-Fetal membranes release 3-Fetal membranes release prostaglandins prostaglandins in in high concentrations at labor which can high concentrations at labor which can increase the intensity of uterine contractionsincrease the intensity of uterine contractions..

Mechanical factors that increase uterine Mechanical factors that increase uterine contractility:contractility:1-Stretch of uterine musculature:1-Stretch of uterine musculature:Stretching smooth muscle organs increases Stretching smooth muscle organs increases their contractility. Because of the repeated their contractility. Because of the repeated fetal movements can also elicit uterine fetal movements can also elicit uterine contractions (twins are born earlier than a contractions (twins are born earlier than a single child).single child).2-Stretch or irritation of the cervix:2-Stretch or irritation of the cervix:Stretching or irritation of the uterine cervix Stretching or irritation of the uterine cervix can elicit uterine contractions. Induction of can elicit uterine contractions. Induction of labor can be done by rupturing the labor can be done by rupturing the membranes so that the baby’s head stretches membranes so that the baby’s head stretches the cervix & irritates itthe cervix & irritates it The mechanism is not known, it could be that The mechanism is not known, it could be that stretching or irritation of nerves in the cervix stretching or irritation of nerves in the cervix initiates reflexes to the body of the uterus or initiates reflexes to the body of the uterus or could be from myogenic transmission of could be from myogenic transmission of signals from the cervix to the body of the signals from the cervix to the body of the uterusuterus..

Onset of labor – a positive feedback Onset of labor – a positive feedback mechanism for its initiation:mechanism for its initiation:- - During pregnancy the uterus undergoes periodic During pregnancy the uterus undergoes periodic episodes of weak & slow rhythmical contractions called episodes of weak & slow rhythmical contractions called Braxon HicksBraxon Hicks contractions. contractions. - This contraction becomes more strong stretching the - This contraction becomes more strong stretching the cervix & force the baby out of the birth canal. This cervix & force the baby out of the birth canal. This process is process is called laborcalled labor & the strong contractions that & the strong contractions that result in final parturition are called labor contractions. result in final parturition are called labor contractions. - - Positive feedback theory:Positive feedback theory: suggests that stretching of suggests that stretching of the cervix by the fetus’ head finally becomes great the cervix by the fetus’ head finally becomes great enough to elicit a strong reflex increase in contractility enough to elicit a strong reflex increase in contractility of the uterine body. This pushes the baby forward, of the uterine body. This pushes the baby forward, which stretches the cervix more & initiate more positive which stretches the cervix more & initiate more positive feedback to the uterine body.feedback to the uterine body.The two positive feedback increase uterine The two positive feedback increase uterine contractions during labor:contractions during labor:1-Stretching the cervix causes the entire body of the 1-Stretching the cervix causes the entire body of the uterus to contract & this contraction stretches the uterus to contract & this contraction stretches the cervix more because of the downward descend of the cervix more because of the downward descend of the baby’s head.baby’s head.2-Cervical stretching causes the pituitary gland to 2-Cervical stretching causes the pituitary gland to secrete oxytocin which increase the uterine secrete oxytocin which increase the uterine contractionscontractions..

Abdominal muscle contractions during labor:Abdominal muscle contractions during labor:Strong uterine contractions & pain signals originate Strong uterine contractions & pain signals originate both from the uterus & from the birth canal. These both from the uterus & from the birth canal. These signals elicit neurogenic reflexes in the spinal cord to signals elicit neurogenic reflexes in the spinal cord to the abdominal muscles causing intense contractions of the abdominal muscles causing intense contractions of these muscles & more force that causes expulsion of these muscles & more force that causes expulsion of the baby.the baby.Mechanics of parturition:Mechanics of parturition:-The uterine contractions during labor begin at the top -The uterine contractions during labor begin at the top of the uterine fundus & spread downward over the body of the uterine fundus & spread downward over the body of the uterus.of the uterus.- Each uterine contractions tends to force the baby - Each uterine contractions tends to force the baby downward toward the cervix.downward toward the cervix.- In the early part of labor, the contractions occur once - In the early part of labor, the contractions occur once every 30 minutes finally once every 1 to 3 minutes.every 30 minutes finally once every 1 to 3 minutes.- - First stage of laborFirst stage of labor is a period of progressive cervical is a period of progressive cervical dilatation until the cervical dilatation is as large as the dilatation until the cervical dilatation is as large as the head of the fetus. This stage lasts for 8 to 24 hours in head of the fetus. This stage lasts for 8 to 24 hours in the first pregnancy & a few minutes after many the first pregnancy & a few minutes after many pregnancies.pregnancies.--The second stage,The second stage, once the cervix is fully dilated, the once the cervix is fully dilated, the fetal membranes rupture and the amniotic fluid pass fetal membranes rupture and the amniotic fluid pass through the vagina & fetus’ head moves rapidly into the through the vagina & fetus’ head moves rapidly into the birth canal until delivery of the fetus. This stage lasts birth canal until delivery of the fetus. This stage lasts from 1 minute after many pregnancy to 30 minutes or from 1 minute after many pregnancy to 30 minutes or more in the first pregnancymore in the first pregnancy..

Separation and delivery of the placenta:Separation and delivery of the placenta:

For 10 to 45 minutes after birth of the baby, For 10 to 45 minutes after birth of the baby, the uterus continues to contract leading to the uterus continues to contract leading to shearing between the walls of the uterus & the shearing between the walls of the uterus & the placenta. placenta. There are two effects that helps There are two effects that helps separation of the placenta.separation of the placenta.

1-Contractions of the uterine smooth muscle 1-Contractions of the uterine smooth muscle after delivery of the baby constricts the blood after delivery of the baby constricts the blood vessels that supplied the placenta.vessels that supplied the placenta.

2-Vasoconstrictor prostaglandins formed at 2-Vasoconstrictor prostaglandins formed at the placental separation site cause additional the placental separation site cause additional blood vessels spasmblood vessels spasm..

Labor pains:Labor pains:-This cramping pain with each uterine -This cramping pain with each uterine contraction caused by hypoxia of the uterine contraction caused by hypoxia of the uterine muscle resulting from compression of the muscle resulting from compression of the blood vessels in the uterus (visceral sensory blood vessels in the uterus (visceral sensory hypogastric nerves).hypogastric nerves).

-During the second stage of labor when the -During the second stage of labor when the fetus is expelled through the birth canal, more fetus is expelled through the birth canal, more severe pain is caused by cervical stretching, severe pain is caused by cervical stretching, perineal stretching & stretching or tearing of perineal stretching & stretching or tearing of structures in the vaginal canal, pain is structures in the vaginal canal, pain is conducted to the mother’s spinal cord & brain conducted to the mother’s spinal cord & brain by somatic nerves.by somatic nerves.Involution of the uterus after parturition:Involution of the uterus after parturition:During the first 4 to 5 weeks after parturition, During the first 4 to 5 weeks after parturition, the uterus involutesthe uterus involutes..

LactationLactationGrowth of the ductal system – role of the Growth of the ductal system – role of the estrogens:estrogens:Large quantities of estrogens secreted by the Large quantities of estrogens secreted by the placenta cause the ductal system of the breast placenta cause the ductal system of the breast to grow & branch.to grow & branch.The stroma of the breasts increases in The stroma of the breasts increases in quantity & large quantities of fat deposited in quantity & large quantities of fat deposited in the stroma.the stroma.The following 4 hormones are important for The following 4 hormones are important for growth of the ductal systems:-growth of the ductal systems:- growth growth hormone, prolactin, the adrenal corticoids & hormone, prolactin, the adrenal corticoids & insulin, they play a role in protein metabolism.insulin, they play a role in protein metabolism.Development of the lobule-alveolar system – Development of the lobule-alveolar system – role of progesterone:role of progesterone:Progesterone acts synergistically with Progesterone acts synergistically with estrogen & with other hormones, it causes estrogen & with other hormones, it causes growth of the breast lobules, with budding of growth of the breast lobules, with budding of the alveoli & development of secretory the alveoli & development of secretory characteristics in the alveolar cellscharacteristics in the alveolar cells..

Initiation of lactation – functional prolactin:Initiation of lactation – functional prolactin:Estrogen & progesterone are essential for development Estrogen & progesterone are essential for development of the breasts during pregnancy but they inhibit milk of the breasts during pregnancy but they inhibit milk secretion secretion – – Prolactin Prolactin is a hormone secreted by AP. Its is a hormone secreted by AP. Its concentration rises steadily from the 5th week of concentration rises steadily from the 5th week of pregnancy until birth of the baby, were it rises to 10 to pregnancy until birth of the baby, were it rises to 10 to 20 times the normal non-pregnant level. It promote 20 times the normal non-pregnant level. It promote milk secretion.milk secretion.

-The placenta secretes large quantities of -The placenta secretes large quantities of human human chorionic somatomammotropin with lactogenic chorionic somatomammotropin with lactogenic propertiesproperties, , colostrums colostrums is the fluid secreted for the first is the fluid secreted for the first few days after parturition & it contains the same few days after parturition & it contains the same concentrations of proteins & lactose as milk, but it has concentrations of proteins & lactose as milk, but it has no fat & it is produced at lower rate than the rate of no fat & it is produced at lower rate than the rate of milk production. After delivery of the baby the level of milk production. After delivery of the baby the level of estrogens & progesterone fall down which promote the estrogens & progesterone fall down which promote the lactogenic effect of prolactin from the mother’s lactogenic effect of prolactin from the mother’s pituitary gland.pituitary gland.

-In addition, the following hormones -In addition, the following hormones – growth hormone, – growth hormone, cortisol, parathyroid hormones and insulin,cortisol, parathyroid hormones and insulin, are are necessary to provide the amino acids, fatty acids, necessary to provide the amino acids, fatty acids, glucose & calcium required for milk formation. Each glucose & calcium required for milk formation. Each time when the baby suckle nervous signals from the time when the baby suckle nervous signals from the nipples to the hypothalamus to cause a 10 to 20-fold nipples to the hypothalamus to cause a 10 to 20-fold surge in prolactin secretionsurge in prolactin secretion..

Hypothalamic control of prolactin Hypothalamic control of prolactin secretion:secretion:

The hypothalamous mainly inhibits The hypothalamous mainly inhibits prolactin secretion. Therefore damage prolactin secretion. Therefore damage to the hypothalamous blockage of the to the hypothalamous blockage of the hypothalamic hypophysial portal system hypothalamic hypophysial portal system increases prolactin secretion, but it increases prolactin secretion, but it depresses secretion of other AP depresses secretion of other AP hormone.hormone. -The prolactin inhibitory hormone is -The prolactin inhibitory hormone is secreted by the hypothalamous & secreted by the hypothalamous & inhibit prolactin secretion by the AP is inhibit prolactin secretion by the AP is similar to catecholamine dopamine, similar to catecholamine dopamine, which is secreted by the arcuate nuclei which is secreted by the arcuate nuclei of the hypothalamus & can decrease of the hypothalamus & can decrease

prolactin secretion to 10 foldprolactin secretion to 10 fold

Suppression of the female ovarian cycles in Suppression of the female ovarian cycles in nursing mothers for many months after nursing mothers for many months after delivery:delivery:

In most nursing mothers, the ovarian cycle In most nursing mothers, the ovarian cycle ceases. During suckling either because of:-ceases. During suckling either because of:-

1- nervous signals from the breasts to the 1- nervous signals from the breasts to the hypothalamushypothalamus

2- or because of increased prolactin secretion, 2- or because of increased prolactin secretion, it inhibits the secretion of gonadotropin it inhibits the secretion of gonadotropin releasing hormone by the hypothalamus which releasing hormone by the hypothalamus which suppress the pituitary gonadotropic hormones suppress the pituitary gonadotropic hormones FSH & LHFSH & LH..

Ejection (or Let-Down”) process in milk Ejection (or Let-Down”) process in milk secretion – function of oxytocin:secretion – function of oxytocin:

When the baby suckles, sensory impulses When the baby suckles, sensory impulses transmitted through somatic nerves from the transmitted through somatic nerves from the nipples to the mother’s spinal cord & then to nipples to the mother’s spinal cord & then to her hypothalamus, where they cause nerve her hypothalamus, where they cause nerve signals that promote oxytocin secretion. signals that promote oxytocin secretion. The oxytocin is carried in the blood to the The oxytocin is carried in the blood to the breasts where it causes the breasts where it causes the myoepithelial cells myoepithelial cells to contractto contract & & expresses milk from the alveoli expresses milk from the alveoli into the ductsinto the ducts. This process is . This process is called milk called milk ejection or milk let-down.ejection or milk let-down.

Inhibition of milk ejection:Inhibition of milk ejection:Psychogenic factors or generalized Psychogenic factors or generalized sympathetic nervous stimulation to the sympathetic nervous stimulation to the mother can inhibit oxytocin & depress milk mother can inhibit oxytocin & depress milk ejectionejection..

Milk composition and the metabolic drain on Milk composition and the metabolic drain on the mother caused by lactation:the mother caused by lactation:-The concentration of lactose in human milk is -The concentration of lactose in human milk is about 50% greater than in cow’s milk, about 50% greater than in cow’s milk, -but the concentration of protein in cow’s milk -but the concentration of protein in cow’s milk is two or more times greater than in human is two or more times greater than in human milk. milk. -Ash, which contains Ca2+ & other mineral is -Ash, which contains Ca2+ & other mineral is lower in human milk compared with cow’s lower in human milk compared with cow’s milk (1/3rd in human milk). milk (1/3rd in human milk). - Two or three grams of calcium phosphate - Two or three grams of calcium phosphate may be lost each day. To supply the needed may be lost each day. To supply the needed calcium and phosphate the parathyroid glands calcium and phosphate the parathyroid glands enlarge & the mother’s bones become enlarge & the mother’s bones become decalcified & this decalcification problem decalcified & this decalcification problem become more during lactationbecome more during lactation..

Composition of MilkComposition of Milk

WaterWaterFatFatLactoseLactoseCaseinCaseinLactalbumin and other proteinsLactalbumin and other proteinsAsh Ash

88.588.53.33.36.86.80.90.90.40.4

0.2 0.2

87.087.03.53.54.84.82.72.70.70.7

0.7 0.7

Constituents Human’s Milk Cow’s MilkConstituents Human’s Milk Cow’s Milk )%( )%( )%( )%(

Antibodies and other anti-infectious Antibodies and other anti-infectious agents in milk:agents in milk:Multiple types of antibodies & anti-Multiple types of antibodies & anti-infectious agents are secreted in milk infectious agents are secreted in milk with nutrients. Also several types of with nutrients. Also several types of white blood cells including neutrophils white blood cells including neutrophils & macrophages which are lethal to & macrophages which are lethal to bacteria that can cause deadly bacteria that can cause deadly infections in newborn babiesinfections in newborn babies..

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