Female reproductive physiology

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FEMALE REPRODUCTIVE PHYSIOLOGY:

Dr.Abhijit Gogoi University of Fiji FEMALE REPRODUCTIVE PHYSIOLOGY

Total rates of secretion of gonadotropic hormones throughout the sexual lives of female and male human beings, showing an especially abrupt increase in gonadotropic hormones at menopause in the female:

Total rates of secretion of gonadotropic hormones throughout the sexual lives of female and male human beings, showing an especially abrupt increase in gonadotropic hormones at menopause in the female

Estrogen secretion throughout the sexual life of the female human being.:

Estrogen secretion throughout the sexual life of the female human being.

Symptoms of menopause :

Symptoms of menopause Sensations of warmth spreading from the trunk to the face (hot flushes; also called hot flashes ), night sweats, and various psychic symptoms are common after ovarian function has ceased, they are prevented by estrogen treatment. In addition, they occur after castration in men. Their cause is unknown. However, they coincide with surges of LH secretion . LH is secreted in episodic bursts at intervals of 30-60 minutes or more (circhoral secretion), and in the absence of gonadal hormones these bursts are large.

Female reproductive system::

Female reproductive system:

Female Reproductive Anatomy and Physiology: Overview:

Ovary Fallopian tube Fimbriae Uterus Cervix Endometrium Vagina Clitoris Labia Female Reproductive Anatomy and Physiology: Overview

Ovary: Details of Histology & Physiology:

Follicle Oocytes Thecal cells Granulosa cells Estrogen  Corpus luteum Corpus luteum Progesterone Inhibin Ovary: Details of Histology & Physiology

Follicular Structure:

Follicular Structure

Physiology of female reproductive cycle:

Definition The cycle of physiological changes in the ovaries, cervix and endometrium under the influence of female sex hormones. Consist of:- ovarian cycle menstrual cycle Physiology of female reproductive cycle

Ovarian Cycle-preovulatory phase:

5 mo. gestation, ovaries contain 6-7 million oogonia. Oogenesis arrested in prophase of 1st meiotic division (primary oocyte). Begins at 15 weeks and at peak at 20 to 28 wk. of gestation Apoptosis occurs: 2 million primary oocytes at birth. 400,000 primary oocytes at puberty. 400 oocytes ovulated during the reproductive years. Ovarian Cycle-preovulatory phase

PowerPoint Presentation:

Ovarian Cycle :- oogenesis Egg forming cells (oöcytes) go through two divisions 1 º = primary 2 º = secondary Starts with a 2n=46 1 º oöcyte that divides, resulting in two n=23 cells, but one is a large 2 º oöcyte and one is a small 1 st polar body that may itself divide Second division only occurs if 2 º oöcyte is fertilized. Results in one large n=23 ovum (egg) and one small n=23 2 nd polar body Thus o ö genesis results in one large fertilized egg (zygote) and possibly three small polar bodies

Oogenesis vs Spermatogeneis:

Oogenesis vs Spermatogeneis Oogenesis Female cannot form oogonia beyond 28 wks and must function with decreasing pool of oocytes Meiosis in females cause formation of one viable oocyte Spermatogenesis Spermatogonia are produced throughout life Each primary spermatogonia gives rise to 64 spermatozoa

The Ovary:

The Ovary Pair of organs, size of unshelled almonds in upper pelvic region Histology - Capsule of dense CT Cortex just deep to capsule contains follicles with egg cells (oöcytes) Medulla is middle region composed of connective tissue, blood vessels & lymphatics Germinal epithelium is peritoneal membrane covering the ovary Capsule Capsule

Ovarian Follicles :

Ovarian Follicles Oöcytes (egg cells) develop within follicles Stages of follicular development Primordial follicle Single layer of squamous cells around the oöcyte Primary follicle Layers of cuboidal granulosa cells around the oöcyte Granulosa cells secrete estrogens

Ovarian follicle:

Ovarian follicle Primary follicle:- granulosa cells flat form stratum granulosum after mitosis Secondary folicle:- granulosa cells further proliferate. Theca folliculi proliferate form theca interna and theca externa theca interna is secretory. Tertiary follicle:- theca cells become steroidogenic upto this stage the fllicular growth is stimulated by FSH alone.

Ovarian cycle:

Ovarian cycle Secondary follicle Antral cavity forms Graafian follicle Follicle mature ready to ovulate oöcyte Ovulation Follicle ruptures releasing oöcyte

Ovarian Follicle :

Ovarian Follicle Graffian follicle:- at about 7 th day the follicle increases in size , antrum becomes larger with fluid , theca interna is more prominent just prior to ovulation completion of the first meiotic division of the primary oocyte of the graffian follicle to form the secondary oocyte and the first polar body.

Ovarian Cycle:- folliculogenesis:

Secondary oocyte confined to graafian follicle. Arrested at metaphase II. ( mature only if fertilized by a sperm, at that time 2 nd polar body is extruded) Under FSH stimulation: Theca cells secrete testosterone. Granulosa cells contain the enzyme aromatase to convert testosterone into estrogen. Granulosa cells form a ring (corona radiata) around oocyte and form mound (cumullus oophorus). Between oocyte and corona radiata is zona pellucida. Provides barrier to the sperm to fertilize the egg. Ovarian Cycle:- folliculogenesis

Ovulation :

One graafian follicle forms bulge on surface of ovary. Extrudes secondary oocyte into the uterine tube. LH causes the empty follicle to become corpus luteum which secretes: Progesterone and estrogen. If not fertilized, becomes corpus albicans. Ovulation

Ovulation :

Ovulation Refers to release of the secondary oocyte from the ovary usually occurs 14 days after onset of menstruation There is rapid swelling of graffian follicle Formation of stigma Release of proteolytic enzymes Dissolution of the capsular wall Rupture of the follicle

Determination of ovulation time:

Determination of ovulation time Basal body temperature:- falls slightly 0.3 – 0.5 ºC and increases after ovulation. Hormone excretion in urine:-excretion of end products of estrogens increase at peak at time of ovulation and end products of progesterones after ovulation Hormone levels in the plasma:- LH and estrogens are increased and FSH levels are decreased at time of ovulation and progesterone level increase at time of ovulation Ultrasound scanning

Corpus Luteum:

Corpus Luteum After ovulation, empty follicle becomes a corpus luteum Corpus Luteum secretes:- Progesterone – completes the preparation of uterine lining Estrogens – work with progesterone Relaxin – relaxes uterine muscles and pubic symphysis Inhibin – decreases secretion of FSH and LH Corpus albicans is a white scar tissue left after the corpus luteum dies.

Summary of ovarian cycle:

Summary of ovarian cycle Ovarian cycle is divided into four phases Development of follicles primitive follicles  primary follicles  secondary follicles  antrun/ developing follicles  maturity follicles ovulation corpus luteum corpus albican

Ovarian cycle:

Ovarian cycle

Follicular Phase:

Lasts from day 1 to about 13. FSH: Follicles become increasingly sensitive to FSH. FSH stimulates the production of FSH receptors on the granulosa cells. Toward the end of the phase, sensitivity of FSH receptors increases. FSH and estradiol stimulate production of LH receptors in graafian follicle. Rapid rise in estradiol from granulosa cells. Negative feedback on LH and FSH. Follicular Phase

PowerPoint Presentation:

Follicular Phase (continued) Hypothalamus increases frequency of GnRH pulses. Augments the ability of anterior pituitary to respond to GnRH, to increase LH secretion. Positive feedback: LH surge begins 24 hours before ovulation. Triggers ovulation. FSH increase stimulates development of new follicles.

PowerPoint Presentation:

Control of Ovarian function - Early and Middle follicular phase

Luteal Phase:

LH stimulates formation of the empty follicle into corpus luteum. Corpus luteum secretes: Progesterone: Plasma concentration rapidly rises. Exerts negative feedback on LH and FSH. Inhibin: Suppresses FSH secretion. Inhibin production decreases towards end of luteal phase. Luteal Phase

Luteal Phase (continued):

Corpus luteum regresses unless fertilization occurs: Estradiol decreases. Progesterone decreases. Withdrawal of estradiol and progesterone cause menstruation to occur. Luteal Phase (continued)

PowerPoint Presentation:

Control of Ovarian function – Late Follicular Phase (LH Surge)

PowerPoint Presentation:

Hormonal levels – Ovarian events

PowerPoint Presentation:

FEMALE REPRODUCTIVE SYSTEM  UTERUS ENDOMETRIUM TWO LAYERS : undergoes cyclic changes which prepare it for implantation of a fertilized ovum (1) FUNCTIONAL LAYER (stratum functionalis) (2) BASAL LAYER (stratum basale) - BORDERS UTERINE LUMEN - SLOUGHED OFF AT MENSTRATION - RETAINED AT MENSTRATION - SOURCE OF CELLS FOR REGENERATION OF FUNCTIONAL LAYER - CONTAINS UTERINE GLANDS STRAIGHT AND SPIRAL ARTERIES

Endometrial cycle:

Endometrial cycle

Stages of uterine cycle:

Stages of uterine cycle The proliferative phase (estrogen phase), occurs before ovulation Secretory phase (progesterone phase) ,occurring after ovulation Desquamation of endometrium known as menstruation

Proliferative phase (estrogen phase):

Proliferative phase (estrogen phase) At start of each cycle endometrium has been desquamated under influence of estrogens the stromal and the epithelial cells proliferate reepithelialized in 4-7 days during next one week justbefore ovulation occurs—the endometrium increases greatly in thickness, owing to increasing numbers of stromal cells and to progressive growth of the endometrial glands and new blood vessels into the endometrium. At the time of ovulation, the endometrium is 3 to 5 millimeters thick.

Changes in cervix in proliferative phase:

Changes in cervix in proliferative phase The cervical glands secrete thin stringy mucus these strings align along length of the canal and help to guide the sperm in proper direction in the female tract

Secretory phase(progesterone phase):

Secretory phase(progesterone phase) During the latter half after ovulation progesterones and estrogens both are secreted from corpus luteum P causes the secretory changes and marked swelling in the endometrium, increasing the tortuosity of the glands cytoplasm of the stromal cells increases , blood supply increases. At the peak of secretory phase the thickness of the endometrium is 5-6 mm.The purpose of all these endometrial changes is to produce a highly secretory endometrium that contains large amounts of stored nutrients to provide appropriate conditions for implantation of a fertilized ovum during the latter half of the monthly cycle

Menstruation :

Menstruation If no fertilization occurs about 2 days before the end of each cycle the corpus luteum involutes and the levels of E and P decrease. The endometrium becomes thinner. Foci of necrosis appear in the endometrium, and these coalesce. There is in addition spasm and then necrosis of the walls of the spiral arteries, leading to spotty hemorrhages that become confluent and produce the menstrual flow. There is vasospasm is probably produced by locally released prostaglandins.during normal menstruation about 40 ml of blood is lost and an additional 35 ml of serous fluid is lost. There is fibrinolysin in the fluid so it is non coagulating

Cyclic changes in the cervix (cervical cycle(:

Cyclic changes in the cervix (cervical cycle ( The cervical sphincter is tighter and more competent during the luteal than during the follicular phase . Follicular phase : Gland : epithelium taller columnar. Cervical mucus : stretch into threads at time of ovulation (Spinnbarkeit test) Absorb more water & salts and when allowed to dry, crystals of Na Cl & K Cl deposits in characteristic pattern (fern pattern (

Cyclic changes in the cervix (cervical cycle):

Cyclic changes in the cervix (cervical cycle) At time of ovulation : Profuse secretion (ovulation cascade)  easily penetrated by spermatozoa. Luteal phase : Glands : more branched. Mucus: more viscous & forms a cervical plug, looses its ability to stretch without breaking and resist sperm penetration. NB : cervical mucous is scanty, viscid, less cellular with negative ferning & spinnbarkeit

Cyclic changes in the vaginal epithelium:

Cyclic changes in the vaginal epithelium

Anovulatory Cycles:

Anovulatory Cycles Ovulation will not occur - surge of LH is not of sufficient First few cycles after the onset of puberty. cycles occurring several months to years before menopause.

PowerPoint Presentation:

Basal body temperature Plasma oestradiol Plasma progesterone Volume of cervical mucus – and sperm penetration Uterine endometrium

Ovarian Hormones:

Ovarian Hormones Estrogens (oestrogens) & progestins important of the estrogens is the hormone b-estradiol, other derivatives of estrogen are estrone and estriol important progestin is progesterone. other are progestin,17 α -hydroxyprogesterone.

Estrogens:

Estrogens Non-pregnant female - only from the ovaries. During pregnancy - also from placenta. 3 estrogens - b-estradiol, estrone, & estriol. Main estrogen by the ovaries - b-estradiol. Estriol – weak estrogen. oxidative product of estradiol and estrone. conversion in the liver.

Estrogens metabolism :

Estrogens metabolism 2% free and remainder is bound 60% to albumin, 38% to gonadal steroid-binding globulin Liver conjugates and form glucuronides and sulfates. Diminished liver function – increases activity of estrogens.

Progestins:

Progestins Important of progestins – progesterone Significant amounts only during the latter half of each ovarian cycle. Large amounts from the placenta in pregnancy - after fourth month of gestation.

Progestins metabolism:

Progestins metabolism 2% free and remainder is bound 80% to albumin, 18% to corticosteroid binding globulin Liver conjugates and form glucuronides. Has short half life.

Mechanism of estrogen action :

Mechanism of estrogen action Free estradiol → enters the cells and diffuse into the nucleus. The specific estrogen receptor protein are intranuclear. The steroid-receptor complex interacts with nuclear DNA →hormone message to nuclear gene structure →production of a messenger RNA, which is transported to cytoplasmic ribosomes where it leads to protein synthesis and the cellular response characteristic of estrogen responsive cells

PowerPoint Presentation:

Estogen mechanism of action

Functions of the estrogens :

Functions of the estrogens Secondary sex characteristics Increase size of ovaries, fallopian tubes,uterus, and vagina. External genitalia enlarge - deposition of fat in the mons pubis and labia majora, enlargement of the labia minora.

Functions of the estrogens:

Functions of the estrogens Vaginal epithelium - from a cuboidal into a stratified type. Stimulate endometrial growth. Fallopian tubes - glandular tissues proliferate. Breast development of the stromal tissues, growth of an extensive ductile system, deposition of fat.

Functions of the estrogens :

Functions of the estrogens Stimulate bone growth – inhibit osteoclastic activity in the bones. accelerate metabolism (burn fat)but only on ethird as that of testosterone reduce muscle mass maintenance of vessel Skin texture - soft and usually smooth

Functions of the estrogens:

Functions of the estrogens Protein synthesis Increase hepatic production of binding proteins slight increase in total body protein. evident by positive nitrogen balance seen on giving estrogens Lipid Increase fat depositition in the subcutaneous tissues Sodium and water retention

Functions of Progesterone:

Functions of Progesterone Most important function – promote secretory changes in endometrium. Increased mucosal secretion of fallopian tubes. Breasts - development of lobules and alveoli and become secretory in nature.

Hypothalamic-Pituitary ovary axis :

Hypothalamic-Pituitary ovary axis GnRH secretes in pulses lasting 5 to 25 minutes - every 1 to 2 hours. Limbic system has control over -intensity & frequency of the pulses. Estrogen has a strong effect to inhibit the production of LH & FSH

Hypothalamic-Pituitaryovary axis :

Hypothalamic-Pituitaryovary axis Inhibitory effect of estrogen is multiplied when progesterone is available. But progesterone itself has little effect. Inhibin ( from granulosa cells) has feedback effects on pituitary.

Female Sexual Response::

Female Sexual Response: As with Males, arousal is controlled by parasympathetic stimulation. Involves engorgement of the erectile tissues. Increased bloodflow to the external genitalia and vaginal walls. Stimulation of secretion of cervical mucous glands and greater vestibular glands.

Female Sexual Response (cont.)::

Female Sexual Response (cont.): Rhythmic contact of the clitoris and vaginal walls, reinforced by touch sensations from the breasts and other stimuli, can lead to orgasm. As with male climax, female climax results in rhythmic peristaltic contractions of the uterus and vaginal walls and associated skeletal muscles. This is thought to enhance the migration of sperm up the female reproductive tract. Female climax is NOT required for fertilization.

Fertilization and pregnancy::

Fertilization and pregnancy:

Fertilization :

Fertilization In humans, fertilization of the ovum by the sperm usually occurs in the ampulla of the uterine tube. Fertilization involves (1) chemo attraction of the sperm to the ovum by substances produced by the ovum (2) adherence to the zona pellucida, the membranous structure surrounding the ovum (3) penetration of the zona pellucida and the acrosome reaction (4) adherence of the sperm head to the cell membrane of the ovum, with breakdown of the area of fusion and release of the sperm nucleus into the cytoplasm of the ovum.

PowerPoint Presentation:

Ejaculation 300 million sperm, 100 reach (uterine) fallopian tube. Capacitation occurs. Fertilization occurs in the uterine tubes. Acrosome of sperm contains hyaluronidase, an enzyme that digests a channel through zona pellucida. Sperm fuses with ovum cell membrane. Fertilization

Blocks to polyspermy:

Blocks to polyspermy If more than one sperm were to fertilize the egg, then the genetic complement would be 3n. In order to prevent multiple sperm penetrations, two responses have evolved in the egg. First, as soon as the first sperm head penetrates the egg, it triggers a massive influx of Na + . This influx depolarizes the egg, making it positive inside. This repels the positively charged sperm, inhibiting penetration of more sperm.

PowerPoint Presentation:

Second, the depolarization triggers an influx of Ca 2+ . This Ca 2+ facilitates the exocytosis of a number of secretory vesicles, known as cortical vesicles. The contents of these vesicles surrounds the egg, swells with water and gels, pushing other sperm away from the egg and blocking their entry.

PowerPoint Presentation:

As fertilization occurs, secondary oocyte completes 2 nd meiotic division. Sperm enters ovum cytoplasm. Ovum nuclear membrane disappears, zygote formed. Centrosome of zygote is derived from sperm cell. Fertilization (continued)

Cleavage and Blastocyst Formation:

Cleavage: 30-36 hrs. after fertilization, the zygote divides by mitosis. About 50-60 hours after fertilization, the early embryo develops into morula. Blastocyst develops: Inner cell mass Fetus. Surrounding chorion: Trophoblasts form placenta. Cleavage and Blastocyst Formation

PowerPoint Presentation:

6 th day after fertilization, blastocyst attaches to uterine wall. Trophoblast cells produce enzymes that allow blastocyst to burrow into endometrium. Implantation

Fertilization::

Fertilization:

PowerPoint Presentation:

Only fertilized egg cells and early cleavage cells are totipotent: Ability to create the entire organism. Reproductive cloning: Adult stem cells can become totipotent if transplanted into egg cell cytoplasm. Therapeutic cloning: Nucleus transplantation to produce stem cells for purpose of growing specific tissue for the treatment of disease. Pluripotent: Cells obtained from inner cell mass of blastocyst (embryonic stem cells) can give rise to all tissues except the placenta. Multipotent: Can give rise to a number of differentiated cells. Embryonic Stem Cells and Cloning

PREGNANCY BEGINS:

THIS RESULTS IN THE ONSET OF A NINE-MONTH RELATION SHIP BETWEEN THE EMBRYO-FETUS, AND THE MOTHER. THIS PHYSIOLOGICAL STATE IS CALLED PREGNANCY. IT IS DIVIDED INTO THREE TRIMESTERS OF THREE MONTHS EACH. PREGNANCY BEGINS

FETO PLACENTAL UNIT:

FETO PLACENTAL UNIT CHOLESTEROL PREGNENOLONE PROGESTERONE DHEAS 16-OH- DHEAS CORTISOL & CORTICOSTERONE DHEAS 16-0H-DHEAS ESTRADIOL ESTRIOL PLACENTA FETAL ADRENAL

TESTS OF PREGNANCY:

1. ASCHEIM ZONDEK TEST 2. FRIEDMAN TEST 3. GALLI-MAININI TEST 4. IMMUNOLOGICAL TESTS a) SHEEP RBC AGGLUTINATION b) LATEX PARTICLE AGGLUTINATION c) GRAVINDEX TEST TESTS OF PREGNANCY

PowerPoint Presentation:

GRAVINDEX: HCG TEST KIT

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CNS: I Trimester: Excitement Depression Irritability II Trimester: Euphoria: a sense of ‘well being’ III Trimester: Worries and anxieties PHYSIOLOGICAL CHANGES IN PREGNANCY

PowerPoint Presentation:

BLOOD VOLUME INCREASED BY 25% HEMODILUTION. ANEMIA CARDIAC OUTPUT INCREASED BY 30% PULSE RATE INCREASED. PERIPHERAL RESISTANCE DECREASES BP IS MAINTAINED NORMAL. CHANGES IN CARDIOVASCULAR SYSTEM

CHANGES IN GASTROINTESTINAL SYSTEM:

MORNING SICKNESS: HYPEREMESIS GRAVIDARUM CONSTIPATION HEARTBURN  ACIDITY DUE TO LES TONE CHANGES IN GASTROINTESTINAL SYSTEM

CUTANEOUS CHANGES:

INCREASED PIGMENTATION PURPLE STRIA: STRIAE GRAVIDARUM RENAL CHANGES INCREASED FREQUENCY. SLIGHT ALBUMINURIA. SODIUM & WATER RETENTION. CUTANEOUS CHANGES

CHANGES IN RESPIRATORY SYSTEM:

 TIDAL VOLUME.  PULMONARY VENTILATION OXYGEN UTILISATION INCREASES. BLOOD CHANGES  ERYTHROCYTE SEDIMENTATION RATE.  COLLOID ONCOTIC PRESSURE EDEMA LOSS OF 1/8th TO 1/10th IRON. CHANGES IN RESPIRATORY SYSTEM

CHANGES IN ENDOCRINES:

HYPOTHALAMO-HYPOPHYSIAL AXIS STOPPED. HCG TAKES OVER. CORPUS LUTEUM AND PLACENTA BECOME MAJOR ENDOCRINE GLANDS PRODUCING ESTROGENS & PROGESTERONE. INCREASED LEVELS OF: PTH, CORTISOL, PROLACTIN & OXYTOCIN. CHANGES IN ENDOCRINES

CHANGES IN METABOLISM:

BMR INCREASED BY 25%. WEIGHT GAIN: 12.5 kg. POSITIVE CALCIUM BALANCE. PROTEIN ANABOLISM POSITIVE NITROGEN BALANCE. HYPER GLYCEMIA INABILITY TO TOLERATE FASTING. CHANGES IN METABOLISM

CHANGES IN MAMMARY GLANDS:

BREASTS ARE ENLARGED. THE AREOLA AND NIPPLES ARE DARKENED & SWOLLEN. CHANGES IN MAMMARY GLANDS

PowerPoint Presentation:

PROFOUND CHANGES OCCUR. UTERUS INCREASES IN WEIGHT & SIZE. BOTH HYPERPLASIA & HYPERTROPHY OCCUR OF BOTH ENDO & MYOMETRIA. WEAK CONTRACTIONS OCCUR IN THE UTERUS CHANGES IN REPRODUCTIVE ORGANS

CHANGES IN REPRODUCTIVE ORGANS contd.:

CERVIX BEGINS TO SOFTEN. OVARIES: NO OVULATION CORPUS LUTEUM OF PREGNANCY INCREASES IN SIZE WITHIN THE OVARY. VAGINA BECOMES HYPERVASCULAR. MUCOSA BECOMES PURPLISH  ACIDITY IN THE VAGINA. CHANGES IN REPRODUCTIVE ORGANS contd.

Implantation::

Implantation:

Chorionic villi:

Chorionic villi

Placenta:

Syncytiotrophoblast secretes enzymes that create blood filled cavities in the maternal tissue. Cytotrophoblast then forms villi that grow into the pools of venous blood. Produces chorion frondosum on the side that faces the uterine wall. Other side of chorion bulges into the uterine cavity. Placenta

Placenta :

Placenta Fully formed placenta is a disc shaped structure with diameter of 15-20 cm and weighs 500gms. Placental membrane consist of :- endothelium of the fetal blood vessels and its basement membrane connective tissue cytotrophoblast and its basement membrane syncytiotrophoblast

PowerPoint Presentation:

Decidual reaction: Endometrial growth. Accumulation of glycogen. Decidua basalis: Maternal tissue in contact with the chorion frondosum. Decidua basalis and chorion fondosum together become placenta. Maternal and fetal blood do not mix. Formation of the Placenta and Amniotic Sac

PowerPoint Presentation:

Envelop the embryo and umbilical cord. Amniotic fluid initially is isotonic, but as fetus develops; concentration changes by urine and sloughed cells of the fetus, placenta, and amniotic sac. Amnion

Placental hormones::

Placental hormones: During early pregnancy, HCG is secreted by the syncitial trophoblasts. Later, the placenta secretes estradiol, progesterone, relaxin and somato-mammotropin.

PowerPoint Presentation:

hCG (Human Chorionic Gonadotropin) Trophoblast cells secrete hCG: Signals corpus luteum not to degenerate until placenta secretes adequate [hormones]. Prevents immunological rejection of implanting embryo. Has thyroid-stimulating ability. Produces effects similar to LH. Basis of pregnancy test.

Function of placental hormones: :

Function of placental hormones: HCG is similar to LH and maintains the corpus luteum in a functional state for 3-4 months. This keeps progesterone levels high and they maintain the functional endometrium. Relaxin increases flexibility in the pelvic joints, as well as suppressing release of oxytocin. Placental progesterone keeps the uterine wall intact. Somatomammotropin acts like prolactin and triggers the mammary glands to develop. Estrogen increases the sensitivity of the myometrium to mechanical irritation, as well as oxytocin stimulation.

Placental Hormones:

hCS (chorionic somatomammotropin): secretion begins at 5 th wk of pregnancy(plasma concentration is proportional to activity of placenta) Actions similar to GH. Actions similar to prolactin. hCS and GH cause diabetic-like effect: Glucose sparing effects by maternal tissues. Ensure sufficient supply of glucose for placenta and fetus. Polyuria. Lipolysis. Placental Hormones

Placental Hormones (continued):

Fetal-placental unit: Placenta must cooperate with the adrenal cortex in the fetus to produce estrogen. Estrogen/estriol stimulates: Endometrial growth. Inhibition of prolactin secretion. Growth of mammary ducts. Enlargement of mother’s uterus. Placental Hormones (continued)

Placental Hormones (continued):

Progesterone: Suppresses uterine contractions. Stimulates uterine growth. Suppresses LH and FSH. Stimulates development of alveolar tissue of the mammary gland. Placental Hormones (continued)

Placenta Function:

Site for exchange of gases and other molecules between maternal and fetal blood. Gas exchange: 02 and C02. Nutrient exchange. Waste exchange. Synthesis of proteins and enzymes. Placenta Function

Parturition:

Estrogen in late pregnancy: Stimulates production of oxytocin receptors in myometrium. Produces receptors for prostaglandins. Produces gap junctions between myometrium cells in uterus. Factors responsible for initiation of labor are incompletely understood. Parturition

PowerPoint Presentation:

Parturition (continued)

Parturition (continued):

Fetal adrenal cortex: Chain of events may be set in motion through CRH production. Fetal adrenal zone secretes DHEAS, which travel from fetus and placenta. Uterine contractions: Oxytocin. Prostaglandins. Parturition (continued)

Labour::

Labour: Towards the end of pregnancy, relaxin secretion falls off, thus, the uterus becomes more sensitive to oxytocin. Initially, the fetus secretes oxytocin into the maternal circulation. The oxytocin stimulates contractions, which push the head down against the cervix.

PowerPoint Presentation:

This pressure on the cervix stimulates the release of oxytocin from the maternal pituitary gland. The maternal oxytocin causes more contractions of the uterus, forcing the head of the fetus against the cervix even harder. This is a positive feedback system.

Labour and delivery::

Labour and delivery: As the head of the fetus is pressed down against the cervix, it thins and then starts to dilate. This stage is known as the Dilation Stage and can last several hours, or days (usually around 8 hours). Once the cervix has dilated, the fetus starts moving through the birth canal. Contractions are maximal and come about 2-3 minutes. This is known as the Expulsion Stage. If the vaginal wall has not stretched enough, tearing may occur.

Labour and delivery cont. ::

Labour and delivery cont. : There is also a chance that the fetus will get stuck in the birth canal (usually caused by insufficient molding of the head. In these cases, a cesarean section is performed. Finally, after expulsion of the fetus, the placenta detaches from the uterine wall and is delivered through the birth canal. This is known as the Placental Stage.

Lactogenesis :

Lactogenesis Phases are:- 1.preparation of breast for milk secretion (mammogenesis) 2.Synthesis and secretion of milk ( lacto genesis) 3.Expulsion of milk ( galactokinesis) 4.Maintainance of lactation (galactopoiesis)

Lactogenesis :

Lactogenesis Stage 1:- in later weeks of pregnancy there is secretion of colostrum rate is only 1/100 th of that of secretion of milk it occurs due to high levels of prolactin and HCS Stage 2 :- occurs after the baby is born due to loss of the estrogens and progesterone thus allowing the lactogenic secretion of prolactin to take place secretion rate is 500- 750 ml/day

Human milk composition :

Human milk composition Human milk has 88.5% water and 11.5% solids. solids have both organic and in organic components it contains 1.proteins: 1-2 gm% 2. Carbohydrates ( lactose) : 6.5-8.5gm% 3. Fats 3.0-5.0 gm% 4. Calcium .03 gm% 5. Minerals 0.18-0.25 gm%

Expulsion of milk: suckling reflex:

Expulsion of milk: suckling reflex Two hormones are involved, PRL and oxytocin. PRL stimulates milk production, while oxytocin is required for the expression of milk from the breast.

Lactation:

Hypothalamus releases PRH. Anterior pituitary releases prolactin: Stimulates milk production. Prolactin secretion primarily controlled by PIH. Oxytocin needed for “milk letdown.” Lactation

Lactation (continued):

Mammary gland: Lobules contain glandular alveoli that secrete milk of the lactating female. Alveoli secrete milk into secondary tubule that converge to form mammary duct. Ampulla: Where milk accumulates during nursing. Neuroendocrine reflex: Act of nursing maintains high levels of prolactin. Sucking may cause release of PRH. Lactation (continued)

Prolactin secretion:

Prolactin secretion

Milk-Ejection Reflex:

Milk-Ejection Reflex

Fertility issues::

Fertility issues:

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