The Female Reproductive System Jen Tynes SELU

The Female Reproductive System Jen Tynes SELU
Ch 28 The Female Reproductive System Jen Tynes SELU

Female Reproductive System
Reproductive Anatomy Puberty and Menopause Oogenesis and the Sexual Cycle Female Sexual Response Pregnancy and Childbirth Lactation

more complex than the males because it serves more purposes produce and deliver gametes, provide nutrition and safe harbor for fetal development, gives birth, and nourish the infant more cyclic, and female hormones secreted in a more complex sequence than the relatively steady secretion in the male

Produce and deliver gametes Provide nutrition and room for fetal development Give birth Nourish infant internal genitalia ovaries, uterine tubes, uterus and vagina external genitalia clitoris, labia minora, and labia majora occupy the perineum primary sex organs ovaries secondary sex organs other internal and external genitalia

Sex Differentiation Male and female are indistinguishable for first 8 to 10 weeks of development Female develops no testosterone or müllerian-inhibiting factor causes degeneration of (male) mesonephric duct paramesonephric duct develops into uterine tubes, uterus and vagina genital tubercle becomes clitoris urogenital folds develop into labia minora labioscrotal folds into labia majora the two sexes indistinguishable for first 8 to 10 weeks of development female reproductive tract develops from the paramesonephric ducts not because of the positive action of any hormone because of the absence of testosterone and müllerian-inhibiting factor (MIF) without testosterone: causes mesonephric ducts to degenerate genital tubercle becomes the glans clitoris urogenital folds become the labia minora labioscrotal folds develop into the labia majora without MIF: paramesonephric ducts develop into the uterine tubes, uterus, and vagina

Ovary Produces eggs and hormones
almond-shaped, 3 cm x 1.5 cm x 1 cm tunica albuginea capsule like on testes cortex produces gametes; medulla holds vessels Each egg develops in its own fluid-filled follicle and is released by ovulation Ligaments attached to uterus by ovarian ligament attached to pelvic wall by suspensory ligament contains ovarian artery, vein and nerves anchored to broad ligament by mesovarium ovaries – female gonads which produce egg cells (ova) and sex hormones almond-shaped and nestled in the ovarian fossa depression in the posterior pelvic wall tunica albuginea capsule like on testes outer cortex where germ cells develop inner medulla occupied by major arteries and veins lacks ducts, instead each egg develops in its own fluid-filled follicle ovulation – bursting of the follicle and releasing the egg ovarian ligaments attached to uterus by ovarian ligament attached to pelvic wall by suspensory ligament contains ovarian artery, vein and nerves anchored to broad ligament by mesovarium ovary receives blood from two arteries: ovarian branch of the uterine artery ovarian artery equivalent to testicular artery in male ovarian and uterine arteries anastomose along margin of ovary give off multiple small arteries that enter the ovary ovarian veins, lymphatics, and nerves also travel through the suspensory ligaments

Anatomy of Ovary The ovary is shaped like an almond and is about 3 cm long. The egg develops in a bubble called a follicle and this bubble bursts, releasing the egg at ovulation. This diagram shows the different developmental stages of a follicle and gives you an idea of the anatomy of the ovary.

Secondary Sex Organs Internal genitalia External genitalia
duct system of uterine tubes, uterus, vagina External genitalia clitoris, labia minora, and labia majora occupy perineum accessory glands beneath skin provide lubrication

Uterine (Fallopian) Tubes
10 cm long, muscular tube lined with ciliated cells Major portions narrow isthmus near uterus body (ampulla): middle portion flares distally into infundibulum with fimbriae Enclosed in superior margin of broad ligament (mesosalpinx) uterine tube (oviduct) or (fallopian tube) canal about 10 cm long from ovary to uterus muscular tube lined with ciliated cells highly folded into longitudinal ridges major portions: infundibulum – flared, trumpet-shaped distal (ovarian) end fimbriae – feathery projections on infundibulum ampulla – middle and longest part isthmus – narrower end toward uterus mesosalpinx – the superior portion of the broad ligament that enfolds uterine tube

Epithelial Lining of Uterine Tube
Secretory cells are in red and green and cilia of ciliated cells are yellow.

The Uterus uterus – thick muscular chamber that opens into the roof of the vagina usually tilts forward over the urinary bladder harbors fetus, provides a source of nutrition, and expels the fetus at the end of its development pear-shaped organ fundus – broad superior curvature body (corpus) – middle portion cervix – cylindrical inferior end lumen is roughly triangular upper two corners are the openings to the uterine tube lower apex is internal os not a hollow cavity, but a potential space in the non-pregnant uterus cervical canal connects the lumen to vagina internal os – superior opening of the canal into the body of the uterus external os – inferior opening of the canal into the vagina cervical glands – secretes mucus that prevents the spread of microorganisms from the vagina to the uterus

Uterus Thick-walled, pear-shaped muscular chamber that opens into vagina and tilts forward over urinary bladder internal and external os of cervical canal openings into uterine tubes in two upper corners Domed fundus above body of organ

Reproductive Tract with Ligaments

Histology of Uterine Wall
Perimetrium - external serosa layer Myometrium - middle muscular layer 1.25 cm thick in nonpregnant uterus smooth muscle produces labor contractions, expels fetus Endometrium simple columnar epithelium with thick layer compound tubular glands stratum functionalis – superficial, shed each period stratum basalis - deep layer, regenerates a new stratum functionalis with each menstrual cycle perimetrium - external serosa layer myometrium - middle muscular layer constitutes most of the uterine wall composed mainly of smooth muscle sweep downward from fundus and spiral around the body less muscular and more fibrous near cervix produces labor contractions, expels fetus endometrium – inner mucosa simple columnar epithelium, compound tubular glands, and a stroma populated with leukocytes, macrophages, and other cells. stratum functionalis – superficial half, shed each menstrual period stratum basalis - deep layer, stays behind and regenerates a new stratum functionalis with each menstrual cycle during pregnancy, the endometrium is the site of attachment of the embryo and forms the maternal part of the placenta from which the fetus is nourished

Normal/Abnormal PAP Smears
PAP smears take a sample of cervical tissue and observe the squamous cells under a microscope to determine if cancer or precancer cells are present. If nuclei are enlarged and cell volume decreased then this reflects the presence of cancer. cervical cancer common among women 30-50 smoking, early age sexual activity, STDs ,and human papillomavirus usually begins in epithelial cells in lower cervix best protection against cervical cancer is early detection by PAP smear cells removed from cervix and vagina and microscopically examined three grades of cervical intraepithelial neoplasia class I mild dysplasia, class II calls for a biopsy, class III results may call for radiation therapy or hysterectomy

Blood Supply uterine blood supply is important to the menstrual cycle and pregnancy uterine artery arises from each internal iliac artery travels and gives off several branches that penetrate myometrium lead to arcuate arteries each travels in a circle around the uterus anastomose with arcuate artery on the other side spiral arteries penetrate through the myometrium into the endometrium wind between endometrial glands toward surface of mucosa rhythmically constrict and dilate making the mucosa alternately blanch and flush with blood

Vessels of Reproductive Tract
Hormonal changes cause spiral artery vasoconstriction, necrosis of stratum functionalis and menstrual flow

Histology of Endometrium
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Surface epithelium Endometrial gland Lamina propria Figure 28.6 (1) 0.1 mm © Ed Reschke

Ligaments of Reproductive Tract
There are several ligaments that hold the uterus, ovaries and fallopian tubes in place.

Ligaments uterus is supported by the muscular floor of the pelvic outlet and folds of peritoneum that form ligaments around the organ broad ligament has two parts mesosalpinx mesometrium on each side of the uterus cardinal (lateral cervical) ligaments – supports the cervix and superior part of the vagina extending to the pelvic wall uterosacral ligaments – paired and attach posterior side of the uterus to the sacrum round ligaments – paired and arise from the anterior surface of the uterus, pass through inguinal canals, and terminate in the labia majoris much like the gubernaculum terminating in the male scrotum

Vagina 8-10 cm distensible muscular tube
allows for discharge of menstrual fluid, receipt of penis, semen and birth of baby Outer adventitia, middle muscularis and inner mucosa Epithelium child - simple cuboidal puberty - estrogens transform to stratified squamous bacteria ferment glycogen rich cells producing acidic pH Tilted posteriorly between rectum and urethra urethra embedded in its anterior wall vagina (birth canal) – cm distensible muscular tube allows for discharge of menstrual fluid, receipt of penis and semen, and birth of baby outer adventitia, middle muscularis, and inner mucosa tilted posteriorly between rectum and urethra vagina has no glands transudation lubricates vagina – “vaginal sweating” serous fluid through its walls and by mucus from the cervical gland above it fornices – blind-ended spaces formed from the vagina extends slightly beyond the cervix transverse friction ridges (vaginal rugae) at lower end mucosal folds form hymen across vaginal opening vaginal epithelium childhood - simple cuboidal puberty - estrogens transform to stratified squamous bacteria ferment glycogen rich cells producing acidic pH in vagina an example of metaplasia – the transformation of one tissue type to another antigen-presenting dendritic cells – route by which HIV from infected semen invades the female body

Vulva (Pudendum) Mons pubis - mound of fat over pubic symphysis; covered by pubic hair Labia majora - thick folds of skin Labia minora - medial, thin hairless folds form vestibule contains urethral and vaginal openings form hoodlike prepuce over clitoris Clitoris - erectile, sensory organ Vestibular bulbs - erectile tissue around vagina Greater and lesser vestibular and paraurethral glands open into vestibule for lubrication external genitalia are collectively called the vulva or pudendum mons pubis - mound of fat over pubic symphysis bearing most of the pubic hair labia majora – pair of thick folds of skin and adipose tissue inferior to the mons pudendal cleft – slit between labia majora labia minora – medial to labia majora are thin hairless folds space between forms vestibule which contains urethral and vaginal openings anterior margins of labia minora join to form hood-like prepuce over clitoris clitoris - erectile, sensory organ with no urinary role primary center for erotic stimulation glans, body, and crura vestibular bulbs - erectile tissue deep to the labia majora cause the vagina to tighten around the penis, enhancing sexual stimulation greater and lesser vestibular and paraurethral glands open into vestibule for lubrication

Female Perineum Showing Vulva

Components of Female Perineum

Breasts Overlies pectoralis major Nipple surrounded by areola
conical body, nipple at apex axillary tail contains many lymphatic vessels Nipple surrounded by areola dermal blood vessels closer to surface melanocytes darken during pregnancy smooth muscle contracts wrinkling skin and erecting nipple in response to cold, touch and arousal Suspensory ligaments from skin, muscle Nonlactating breast has little glandular tissue breast – mound of tissue overlying the pectoralis major enlarges at puberty and remains so for life most of the time it contains very little mammary gland mammary gland – develops within the breast during pregnancy remains active in the lactating breast atrophies when a woman ceases to nurse two principal regions of the breast: body – conical to pendulous, with the nipple at its apex axillary tail – extension toward the armpit lymphatics in axillary tail are important as a route for breast cancer metastasis nipple surrounded by circular colored zone the areola blood capillaries and nerves closer to skin surface – more sensitive sensory nerve fibers of areola trigger a milk ejection reflex when an infant nurses areolar glands – intermediate between sweat glands and mammary glands secretions protect the nipple from chapping and cracking during nursing smooth muscle fibers in dermis of areola that contract in response to cold, touch, and sexual arousal wrinkling the skin and erecting the nipple

Anatomy of Lactating Breast
Breast feeding has several benefits…. Not just for infant but also mom. It helps stimulate uterine contracts which allows the uterus to get back to prepregnancy size, it decreases the chances of breast & ovarian cancer later in life, and it burns roughly 500 calories a day just by producing milk– some mothers also report that they do not have periods while nursing; however, this is not an effective means of birth control. It may also help reduce her chances of osteoporosis & hip fractures after menopause. Some women find it very convenient, since you don’t have to heat up a bottle in the middle of the night or pack formula around during shopping trips and find a way to heat it--- one huge plus is that it’s basically free- way cheaper than formula. On the downside some mothers find it difficult to nurse b/c they either don’t produce enough milk, they need to return to work, or they find they are the only person who can feed the infant and for some new mom’s this puts a lot of stress on them…. Breast milk can be pumped and stored in a freezer for several months (up to 6 months if stored correctly in a deep freeze) and there are locations that purchase or take donated breast milk for medical purposes (to feed infants in ICU, help burn pts and cancer pts). How does the infant benefit- recent studies show breast fed children have higher IQs, possibly develop a unique mother-child relationship, receive antibodies from the mother and therefore are less sick than other babies- which may continue throughout childhood. Protects baby against asthma, infant less like to have colic, has right amt of nutrients and infants tend to be leaner and w/out excess fat can hit motor milestones sooner (such as standing up and walking) which may also advance brain activity, surveys show that children breastfed are less likely to be diabetic or obese later in life. Are less likely to die of SIDS the first yr, or have lymphoma, leukemia, Hodgkin's disease or high cholesterol later in life; however, more studies need to be conducted to verify this is b/c of breast milk.

Anatomy of Lactating Breast

Sagittal Section of Breast
the nonlactating breast consists mostly of adipose and collagenous tissue breast size determined by amount of adipose tissue suspensory ligaments attach breast to dermis of overlying skin and fascia of the pectoralis major system of ducts through fibrous stroma and converge on the nipple mammary gland develops during pregnancy 15 to 20 lobes around the nipple lactiferous duct drains each lobe dilates to form lactiferous sinus which opens into the nipple

Breast of Cadaver Figure 28.9b Adipose tissue Suspensory ligaments
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Adipose tissue Suspensory ligaments Areola Nipple Figure 28.9b (b) Breast of cadaver From Anatomy & Physiology Revealed, © The McGraw-Hill Companies, Inc./The University of Toledo, photography and dissection

Breast Cancer 1 out of 8 American women
Tumors begin with cells from mammary ducts may metastasize by lymphatics Symptoms may include palpable lump, skin puckering, skin texture and drainage from nipple Most breast cancer is nonhereditary some stimulated by estrogen Risk factors include aging, ionizing radiation, carcinogenic chemicals, alcohol, smoking and fat intake 70% lack risk factors breast cancer occurs in 1 out of 8 American women tumors begin with cells from mammary ducts may metastasize by mammary and axillary lymphatics signs may include palpable lump (the tumor), skin puckering, changes in skin texture, and drainage from nipple most breast cancer is nonhereditary two breast cancer genes were discovered in the 1990s BRCA1 and BRCA2 some stimulated long periods of fertility and estrogen exposure risk factors include aging, exposure to ionizing radiation, carcinogenic chemicals, excessive alcohol and fat intake, and smoking 70% of cases lack identifiable risk factors tumor discovery usually during breast self-examination (BSE) – monthly for all women mammograms (breast X-rays) late 30s – baseline mammogram every two years over 50 – yearly treatment of breast cancer lumpectomy – removal of tumor only simple mastectomy – removal of the breast tissue only or breast tissue and some axillary lymph nodes radical mastectomy – removal of breast, underlying muscle, fascia, and lymph nodes surgery followed by radiation or chemotherapy breast reconstruction from skin, fat, and muscle from other parts of the body

Cancer Screening and Treatment
A and B are mammogram procedure and results. B shows tumor. C is pt after mastectomy and d is same pt after reconstructive surgery. Today they can do a mastectomy and reconstruct the breast during the same procedure.

Puberty Begins at age 9-10 (US) Triggered by rising levels of GnRH
stimulates anterior lobe of pituitary to produce follicle-stimulating hormone (FSH) luteinizing hormone (LH) Follicles develop and begin to secrete estrogen and progesterone puberty begins at age 8-10 for most girls in US triggered by rising levels of GnRH stimulates anterior lobe of pituitary to produce follicle-stimulating hormone (FSH) luteinizing hormone (LH) FSH stimulates developing ovarian follicles and they begin to secrete estrogen, progesterone, inhibin, and a small amount of androgen estrogens are feminizing hormones with widespread effects on the body estradiol (most abundant), estriol, and estrone

Puberty Thelarche - development of breasts
Pubarche - growth of pubic and axillary hair; apocrine and sebaceous glands Menarche - first menstrual period requires at least 17% body fat in teenager, 22% in adult leptin stimulates gonadotropin secretion improved nutrition ( body fat) has lowered avg. age of onset to 12 Female hormones secreted cyclically and in sequence thelarche – onset of breast development is the earliest noticeable sign of puberty initial duct and lobule formation – estrogen, progesterone and prolactin completion of duct and lobule formation – glucocorticoids and growth hormone adipose and fibrous tissue complete breast enlargement by age 20 pubarche - appearance of pubic and axillary hair, sebaceous glands, and axillary glands androgens from ovaries and adrenal cortex stimulates pubarche and libido menarche - first menstrual period requires at least 17% body fat in teenager, 22% in adult improved nutrition has lowered age of onset to age 12 leptin stimulates gonadotropin secretion if body fat and leptin levels drop too low, gonadotropin secretion declines and a female’s menstrual cycle might cease first few menstrual cycles are anovulatory (no egg ovulated) girls begin ovulating regularly about a year after they begin menstruating

Hormones of Puberty estradiol progesterone
stimulates vaginal metaplasia stimulates growth of ovaries and secondary sex organs stimulates growth hormone secretion increase in height and widening of the pelvis responsible for feminine physique because it stimulates the deposition of fat makes a girl’s skin thicker but remains thinner, softer, and warmer than males of the corresponding age progesterone primarily acts on the uterus preparing it for possible pregnancy in the second half of the menstrual cycle estrogens and progesterone suppress FSH and LH secretion through negative feedback inhibin selectively suppresses FSH secretion hormone secretion is distinctly cyclic and the hormones are secreted in sequence

Climacteric Midlife change in hormone secretion Results
due to age related depletion of follicles occurs with menopause (cessation of menstruation); average age of 52 Results atrophy of uterus, vagina and breasts skin becomes thinner, bone mass declines, and risks of cardiovascular disease increase hot flashes (sudden dilation of cutaneous arteries) occur several times a day HRT = hormone replacement therapy climacteric -midlife change in hormone secretion accompanied by menopause – cessation of menstruation female born with about 2 million eggs, climacteric begins when there are about 1000 follicles left follicles less responsive to gonadotropins less estrogen and progesterone secretion uterus, vagina, and breast atrophy intercourse becomes uncomfortable as vagina becomes thinner, less distensible, and drier vaginal infections more common skin becomes thinner cholesterol levels rise increasing the risk of cardiovascular disease bone mass declines producing increased risk for osteoporosis blood vessels constrict and dilate in response to shifting hormone balances hot flashes – spreading sense of heat from the abdomen to the thorax, neck, and face hormone replacement therapy (HRT) – low doses of estrogen and progesterone to relieve some of these symptoms risks and benefits are still being debated

Evolution of Menopause
theory – older mother would not live long enough to rear an infant to a survivable age better to become infertile and help rear her grandchildren Pleistocene ice age skeletons show early hominids rarely lived past age 40 menopause may be an artifact of modern nutrition and medicine allowing us to live longer than our ancestors

Oogensis and Sexual Cycle
Reproductive cycle - events occurring between fertilization and birth Sexual cycle - events recurring every month when pregnancy does not occur ovarian cycle = events in ovaries menstrual cycle = parallel changes in uterus

Oogenesis Monthly event produces haploid egg by meiosis
Embryonic development of ovary female germ cells arise from yolk sac differentiate into oogonia, multiply transform into primary oocytes - early meiosis I most degenerate (atresia) by childhood by puberty 400,000 oocytes remain FSH stimulates completion of meiosis I, produces secondary oocyte and 1st polar body proceeds to meiosis II and ceases until fertilization after fertilization , releases 2nd polar body reproductive cycle – sequence of events from fertilization to giving birth sexual cycle - events that recur every month when pregnancy does not intervene consists of two interrelated cycles controlled by shifting patterns of hormone secretion ovarian cycle - events in ovaries menstrual cycle - parallel changes in uterus

Oogenesis and Follicle Development
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Development of egg (oogenesis) Development of follicle (folliculogenesis) Before birth Oocyte Mitosis 2n Multiplication of oogonia Nucleus Primordial follicle Follicular cells Primary oocyte 2n No change Adolescence to menopause Meiosis I Secondary oocyte n Primary follicle Granulosa cells n First polar body (dies) Granulosa cells Secondary follicle Zona pellucida Theca folliculi Tertiary follicle Antrum Cumulus oophorus Theca interna Secondary oocyte (ovulated) n Theca externa If not fertilized If fertilized Ovulation of mature (graafian) follicle Bleeding into antrum Figure 28.11 n n n Ovulated oocyte Dies n Meiosis II Follicular fluid Second polar body (dies) Corpus luteum 2n Zygote Embryo (Primordial & Primary follicle): © Ed Reschke;(Secondary follicle): © The McGraw-Hill Companies, Inc./Photo by Dr. Alvin Telser; (Tertiary follicle): Manfred Kage/Peter Arnold, Inc.; (Graafian): Landrum Dr. Shettles; (Corpus luteum): © The McGraw-Hill Companies, Inc./Photo by Dr. Alvin Telser

a: © Ed Reschke; b: Manfred Kage/Peter Arnold, Inc
Ovarian Follicles Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Tunica albuginea of ovary Primordial follicles Granulosa cells Follicular cells Oocyte (egg) Oocyte nucleus Zona pellucida Primary follicles Cumulus oophorus Oocytes Antrum Theca folliculi (a) 50 µm (b) 100 µm a: © Ed Reschke; b: Manfred Kage/Peter Arnold, Inc Figure a-b

Folliculogenesis folliculogenesis – the development of the follicles around the egg than undergoes oogenesis primordial follicles consists of a primary oocyte in early meiosis surrounded by a single layer of squamous follicular cells follicular cells connected to the oocyte by fine cytoplasmic processes for passage of nutrients and chemical signals concentrated in the cortex of the ovary most wait 13 to 50 years before they develop further adult ovary has 90% to 95% primordial follicles primary follicles have larger oocytes and follicular cells that still form a single layer secondary follicles still larger oocytes and follicular cells now stratified (granulosa cells) zona pellucida – layer of glycoprotein gel secreted by granulosa cells around the oocyte theca folliculi – connective tissue around the granulosa cells condenses to form a fibrous husk

Folliculogenesis tertiary follicles mature (graafian) follicles
granulosa cells begin secreting follicular fluid accumulate in little pools in the follicular wall - this defines the tertiary follicles as they enlarge, the pools merge forming a single fluid-filled cavity, the antrum antral follicles – tertiary and mature follicles preantral follicles – earlier stages of the follicles cumulus oophorus – a mound of granulosa cells on one side of the antrum that covers the oocyte and secures it to the follicular wall corona radiata – innermost layer of cells in the cumulus surrounding the zona pellucida and the oocyte protective barrier around the egg with a similar function as the blood-testis barrier theca folliculi continues to differentiate forming two layers theca externa – outer fibrous capsule rich in blood vessels theca interna – inner cellular, hormone secreting layer producing androgens (androstenedione and testosterone), and granulosa cells converts them to estradiol mature (graafian) follicles normally only one follicle from each month’s cohort becomes a mature follicle destined to ovulate remainder degenerate

Histology of Ovarian Follicles
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Granulosa cells Oocyte (egg) Oocyte nucleus Zona pellucida Cumulus oophorus Antrum Theca folliculi (b) 100 µm Manfred Kage/Peter Arnold, Inc Figure 28.12b

Sexual Cycle Averages 28 days, ranges from 20 to 45
Hormone cycle: hierarchy of control hypothalamus pituitary  ovaries  uterus Follicular phase (2 weeks) menstruation occurs during first 3 to 5 days of cycle uterus replaces lost endometrium and follicles grow Luteal phase (2 weeks) corpus luteum stimulates endometrial thickening endometrium lost without pregnancy sexual cycle averages 28 days, varies from 20 to 45 days hormones of the hypothalamus regulate the pituitary gland pituitary hormones regulate the ovaries ovaries secrete hormones that regulate the uterus basic hierarchy of hormonal control hypothalamus pituitary  ovaries  uterus ovaries exert feedback control over hypothalamus and pituitary cycle begins with 2 week follicular phase menstruation occurs during first 3 to 5 days of cycle uterus replaces lost tissue by mitosis and cohort of follicles grow ovulation around day 14 –remainder the of follicle becomes corpus luteum next 2 weeks the luteal phase corpus luteum stimulates endometrial secretion and thickening if pregnancy does not occur, endometrium breaks down in the last 2 days menstruation begins and the cycle starts over

Menstrual Cycle Menstrual cycle (avg 28 day cycle):
Menstruation (aka Menses or Period) typically lasts 5-7 days and occurs during the Follicular Phase. Follicular Phase occurs for days. Then Ovulation takes place (the releasing of the egg from the ovary), followed by the Luteal Phase which also occurs for days. Hormones trigger each phase to occur. Estradiol will surge which signals LH to spike- the LH surge is what triggers the ovaries to release the egg (FSH is also a player here, but LH increases more). After ovulation both LH and FSH decrease, when they were at their peaks- Progesterone began to increase.. It continues to increase for the first several days of the Luteal Phase and then begins to decline. Once all hormones have declined, the “period” will start and the Follicular Phase begins again. So what’s one major thing that will affect your menstrual cycle? STRESS! If you start to workout everyday, your body views that as stress. If you have an exam coming up, plans for a wedding, a job interview, terminally ill family member, etc– all of those are forms of stress that impact the systems of your body. Now, you have heard that stress will cause your “period” to be late. Is that true? Yes, it is. Now, can it affect it at any time during the cycle (as far as making the period late?)? Nope. The Luteal Phase is like clockwork- it almost always (98% of the time for an average 28 day cycle) is days long. So- how does stress affect it… well, the Follicular Phase is variable- if you are under stress during the first days of the cycle- then ovulation gets postponed. Think of it as a females way of increasing her chance to conceive. If you are super stressed out, her body is thinking “Okay, the chances of intercourse in the next few days is pretty slim… lets keep the egg here for a little bit longer and then maybe we’ll have a better chance of getting fertilized.” There’s no point in waiting the energy it took to mature that follicle (egg), if it’s not going to be fertilized. There are some basic physical things that occur during ovulation. Any idea what happens??? The 3 standard physical features are: 1. Cervical positioning- the cervix will be higher, will open, is softer, and moist. This allows sperm to easily enter. 2. Waking body temperature or Basal Body Temperature (BBT)- At the time of ovulation the body temperature will increase about a degree. So if you chart your body temperature every morning (around the same time) and you find it’s 96.7 degrees (give or take 0.3 degrees) for the first 2 weeks and then one morning it spikes to 97.6, you are either near ovulation or ovulating (or you are sick). Some women do not increase as much as others… the minimum increase is degrees. Why would your body temp increase?? If you raise chickens from eggs, what do you do w/ them?? You place them in an incubator– the females body acts like an incubator to keep that egg nice and warm. You will find that your body temp stays roughly a degree higher until menstruation begins or until you give birth. 3. Cervical discharge- After menstruation the vaginal area stays somewhat dry. As you near ovulation it becomes more moist. Around the time of ovulation the moisture increases and the cervix will discharge an “eggwhite” mucus. It’s called “eggwhite” b/c it often appears like that of eggwhites. This is a slippery and stretchy fluid. Why would this occur?? It’s the perfect medium for sperm to swim… if the vagina, cervix, etc is very dry- then is it easy for sperm to swim? NO- you can’t swim in a pool that doesn’t have any water… But the eggwhite discharge is the perfect type of “water” and the sperm can easily swim to find the egg. By understanding when a female ovulates you, you can increase your chances of conception, use it as a “natural” birth control method or along w/ other forms of birth control. Are all sperm created equal?? Nope. So who determines the sex of the baby? Is it mom or dad? Mom has chromosomes XX; therefore, w/ meiosis, she can only give up an “X” to the egg. Whereas dad has XY and the sperm can contain an “X” or a “Y”. So Dad determines the sex of the baby. If the sperm that fertilizes the egg is an “X” then the baby is female and if it’s “Y” then it’s male. Are “X” & “Y” sperm identical other than that chromosome?? Nope- you find that “X”- our girls… have more genetic material, are slower swimmers, but can deal w/ changes in temperature and pH… they are hardy. Think of them as your marathon runners. “Y”- our boys… are fast swimmers, but they can’t deal w/ pH changes or temperature changes. So think of them as your sprinters. Therefore, in theory, you can influence the likelihood of having a male or female child. So- if you know when you are ovulating, then how can you influence the chances of having a boy vs a girl? Well, first- lets talk about sperm and egg viability. Sperm typically live for 72 hrs, w/ the “X” lasting longer. Eggs usually only last 36 hrs or so. Lets say you ovulate on day 15. If you have intercourse on day 13- then are your more likely to have a boy or girl?? A girl- b/c the egg wasn’t available to be fertilized at the time of intercourse… the boys die off faster and the “hardy” girls are hanging out waiting for the egg to be released. Now, if you have intercourse on day 16- you are more likely to have a boy b/c the “Y”s swim faster and beat the girls to the egg. (Remember they are your sprinters, the egg is available for fertilization and the boys beat the “X” sperm). FYI- some studies show that not all sperm race to fertilize the egg. It is believed that a portion of sperm are “warriors” and their job is to fight any foreign sperm from fertilizing the egg. For example, if a female has intercourse w/ two different males, then some sperm from both males will be “protectors” or “warriors” to help increase their chances of fertilization.

Ovarian Cycle - Follicular Phase
ovarian cycle – in three principal steps follicular phase, ovulation, and luteal phase this cycle reflects what happens in the ovaries and their relationship to the hypothalamus and pituitary much remains unknown about the timing of folliculogenesis follicular phase extends from the beginning of menstruation until ovulation day 1 to day 14 of an average cycle preovulatory phase – from the end of menstruation until ovulation most variable part of the cycle and it is seldom possible to reliably predict the date of ovulation preparation for the follicular phase begins almost two month earlier shortly after ovulation a new cohort of preantral follicles descend form the cortex deeper into the ovary begins to grow and each develops an antrum selection window of 5 days in which one of them is selected as the dominant follicle to mature and ultimately ovulate in the next cycle FSH stimulates continued growth of the cohort, but the dominant follicle above all FSH stimulates the granulosa cells of the antral follicles to secrete estradiol dominant follicle becomes more sensitive to FSH and LH grows and becomes mature (graafian) follicle while others degenerate Menstruation (day 1) to ovulation(14) (variable) Difficult to predict date of ovulation Contains menstrual and preovulatory phases

Ovarian Cycle - Preantral Phase
Discharge of menstrual fluid (days 1-5) Before follicle develops antrum primordial and primary follicles

Ovarian Cycle - Antral Phase
Day 6 to 14, one dominant follicle advances to mature (graafian) follicle; secretes estrogen

Ovarian Cycle - Ovulation
ovulation – the rupture of the mature follicle and the release of its egg and attendant cells typically around day 14 estradiol stimulates a surge of LH and a lesser spike of FSH by anterior pituitary LH induces several events primary oocyte completes meiosis I produces secondary oocyte and first polar body follicular fluid builds rapidly and follicle swells looks like a blister on the ovary surface follicular wall weakened by inflammation and proteolytic enzymes mature follicle approaches rupture ovulation takes only 2 or 3 minutes nipple-like stigma appears on ovary surface over follicle seeps follicular fluid for 1 or 2 minutes follicle bursts and remaining fluid oozes out carrying the secondary oocyte and cumulus oophorus normally swept up by ciliary current and taken into the uterine tube uterine tube prepares to catch the oocyte when it emerges it swells with edema its fimbriae envelop and caress the ovary in synchrony with the woman’s heartbeat cilia create gentle current in the nearby peritoneal fluid many oocytes fall into the pelvic cavity and die couples attempting to conceive a child or avoid pregnancy need to be able to tell when ovulation occurs cervical mucus becomes thinner and more stretchy resting body temperature rises 0.4° to 0.6° F best measured first thing in the morning before arising from bed record for several days to see the difference LH surge occurs about 24 hours prior to ovulation detected with home testing kit twinges of ovarian pain (mittelschmerz) lasts from a few hours to a day or so at the time of ovulation best time for conception within 24 hours after the cervical mucus changes and the basal temperature rises Mature follicle ruptures, releases oocyte influenced by LH

Histology of Ovarian Follicles

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Endoscopic View of Ovulation
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Infundibulum of uterine tube Fimbriae Cumulus oophorus Oocyte Stigma Ovary 0.1 mm Figure 28.15 © Landrum B. Shettles, MD

Pituitary-Ovarian Axis

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Ovarian Cycle - Luteal Phase
luteal (postovulatory) phase - days 15 to day 28, from just after ovulation to the onset of menstruation if pregnancy does not occur, events happen as follows: when follicle ruptures it collapses and bleeds into antrum clotted blood is slowly absorbed granulosa and theca interna cells multiply and fill antrum dense bed of capillaries grows amid them ovulated follicle has now become the corpus luteum named for a yellow lipid that accumulates in the theca interna cells cells now called lutein cells transformation from ruptured follicle to corpus luteum is regulated by LH LH stimulates the corpus luteum to continue to grow and secrete rising levels of estradiol and progesterone 10 fold increase in progesterone is the most important aspect of the luteal phase progesterone has a crucial role in preparing the uterus for the possibility of pregnancy LH and FSH secretion declines over the rest of the cycle high levels of estradiol and progesterone, along with inhibin from the corpus luteum has a negative feedback effect on the pituitary if pregnancy does not occur, the corpus luteum begins the process of involution (shrinkage) beginning about day 22 (8 days after ovulation) by day 26 involution is complete and becomes inactive bit of scar tissue, the corpus albicans with diminishing ovarian steroid secretion, FSH levels rise ripening a new cohort of follicles ovaries usually alternate from month to month Corpus luteum - forms from ruptured follicle, under influence of LH; secretes progesterone

Menstrual Cycle - Proliferative Phase
menstrual cycle - consists of a buildup of the endometrium during most of the sexual cycle, followed by its breakdown and vaginal discharge divided into four phases: proliferative phase, secretory phase, premenstrual phase, and menstrual phase first day of noticeable vaginal discharge is defined as day 1 of the sexual cycle averages 5 days long proliferative phase – layer of endometrial tissue (stratum functionalis) lost in the last menstruation is rebuilt at day 5 of menstruation, the endometrium is about 0.5 mm thick consists only of stratum basalis as new cohort of follicles develop, they secrete more and more estrogen estrogen stimulates mitosis in the stratum basalis and the prolific regrowth of blood vessels regenerating the functionalis by day 14 is 2 to 3 mm thick estrogen also stimulates endometrial cells to produce progesterone receptors Day 6-14 rebuild endometrial tissue mitosis occurs in stratum basalis result of estrogen from developing follicles

Menstrual Cycle - Secretory Phase
secretory phase – endometrium thickens still more in response to progesterone from corpus luteum day 15 to day 26 secretion and fluid accumulation rather than mitosis progesterone stimulates endometrial glands to secrete glycogen glands grow wider, longer and more coiled endometrium 5 to 6 mm thick a soft, wet, nutritious bed available for embryonic development premenstrual phase – period of endometrial degeneration last 2 days of the cycle corpus luteum atrophies and progesterone levels fall sharply triggers spasmodic contractions of spiral arteries causes endometrial ischemia (interrupted blood flow) brings about tissue necrosis and menstrual cramps pools of blood accumulate in stratum functionalis necrotic endometrium mixes with blood and serous fluid – menstrual fluid Further thickening of endometrium due to secretion and fluid accumulation -- not mitosis Due to progesterone stimulation of glands

Menstrual Cycle Premenstrual Phase
menstrual phase – discharge of menstrual fluid from the vagina (menses) first day of discharge is day 1 of the new cycle average woman expels about 40 mL of blood and 35 mL of serous fluid over a 5 day period contains fibrinolysin so it does not clot Involution of corpus luteum, progesterone falls spiral arteries constrict causes endometrial ischemia stratum functionalis sloughs

Menstrual Cycle - Menstrual Phase
Blood, serous fluid and endometrial tissue are discharged

Endometrial Changes Figure 28.16 Secretion Endometrial gland Stratum
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Secretion Endometrial gland Stratum functionalis Spiral artery Stratum basalis Myometrium (a) Proliferative phase (b) Secretory phase (c) Menstrual phase Figure 28.16

Female Sexual Response

physiological changes that occur during intercourse differences from male excitement and plateau labia minora becomes congested and often protrude beyond the labia majora labia majora become reddened and enlarged then flatten and spread away from vaginal orifice vaginal transudate – serous fluid that seeps through the walls of the canal greater vestibular gland secretion moistens the vestibule and provides lubrication lower 1/3 of vagina constricts – the orgasmic platform narrower canal and vaginal rugae enhance stimulation and help induce orgasm in both partners tenting effect – uterus stands nearly vertical, where normally it tilts forward over the bladder breasts swell and nipples become erect stimulation of the erect clitoris brings about erotic stimulation thrusting of the penis and pressure between the pubic symphyses of the partners 28-62

orgasm late in plateau phase, many women experience involuntary pelvis thrusts, followed by 1 to 2 seconds of “suspension” or “stillness” preceding orgasm orgasm – intense sensation spreading from the clitoris through the pelvis sometimes with pelvic throbbing and a spreading sense of warmth pelvic platform gives three to five strong contractions about 0.8 sec apart cervix plunges spasmodically into vagina and pool of semen uterus exhibits peristaltic contraction anal and urethral sphincters constrict paraurethral glands (homologous to the prostate) sometimes expel copious fluid similar to prostatic fluid (female ejaculation) tachycardia, hyperventilation sometimes women experience reddish, rash-like flush that appears on the lower abdomen, chest, neck, and face

resolution the uterus drops forward to its resting position orgasmic platform quickly relaxes rest of the vagina returns more slowly to its normal dimensions flush disappears quickly areolae and nipples undergo rapid detumescence may take 5 to 10 minutes for breasts to return to their normal size postorgasmic outbreak of perspiration women do not have refractory period may quickly experience additional orgasms

Pregnancy and Childbirth
Gestation (pregnancy) lasts an average of 266 days from conception to childbirth gestational calendar measured from first day of the woman’s last menstrual period (LMP) Birth predicted 280 days from LMP 3 three month intervals called trimesters pregnancy from a maternal standpoint adjustments of the woman’s body to pregnancy mechanism of childbirth gestation (pregnancy) lasts an average of 266 days from conception to childbirth gestational calendar measured from first day of the woman’s last menstrual period (LMP) birth predicted 280 days (40 weeks) from LMP term – the duration of pregnancy 3 three month intervals called trimesters conceptus – all products of conception – the embryo or fetus, the placenta, and associated membranes blastocyst – the developing individual is a hollow ball the first 2 weeks embryo - from day 16 through 8 weeks fetus – beginning of week 9 to birth attached by way of an umbilical cord to a disc-shaped placenta provides fetal nutrition and waste disposal, secretes hormones that regulate pregnancy, mammary development, and fetal development neonate - newborn to 6 weeks

Prenatal Development Age based terminology
blastocyst is less than 2 weeks old embryo is from 2 to 8 weeks old fetus is 9 weeks to birth neonate - newborn to 6 weeks

Hormones of Pregnancy HCG (human chorionic gonadotropin) Estrogens
secreted by trophoblast within 9 days of conception prevents involution of corpus luteum Estrogens increases to 30 times normal before birth corpus luteum is source for first 12 weeks until placenta takes over causes uterine, mammary duct and breast enlargement hormones with the strongest influence on pregnancy are: estrogens progesterone human chorionic gonadotropin human chorionic somatomammotropin all primarily secreted by the placenta corpus luteum is important source for the first several weeks if corpus luteum removed before 7 weeks, abortion from week 7 to 17, the corpus luteum degenerates and placenta takes over its endocrine function human chorionic gonadotropin (HCG) secreted by blastocyst and placenta detectable in urine 8 to 9 days after conception by home pregnancy test kits stimulates growth of corpus luteum secretes increasing amounts of progesterone and estrogen increases to 30 times normal by the end of gestation corpus luteum is source for first 12 weeks until placenta takes over gradually from weeks 7 to 17 causes tissue growth in the fetus and the mother mother’s uterus and external genitalia enlarge mammary ducts grow, breasts increase to nearly twice normal size relaxed pubic symphysis and widens pelvis

Hormones of Pregnancy Progesterone
secreted by placenta and corpus luteum suppresses secretion of FSH and LH preventing follicular development prevents menstruation, thickens endometrium stimulates development of acini in breast HCS (human chorionic somatomammotropin) secreted from placenta in direct proportion to its size  mother’s glucose usage and  release of fatty acids progesterone secreted by placenta and corpus luteum suppresses secretion of FSH and LH preventing follicular development during pregnancy suppresses uterine contractions prevents menstruation, thickens endometrium promotes proliferation of decidual cells of the endometrium on which the blastocyst feeds stimulates development of acini in breast in another step toward lactation human chorionic somatomammotropin (HCS) placenta begins its secretion about 5th week increases steadily until term in proportion to placental size effects seem similar to growth hormone, but weaker seems to reduce the mother’s insulin sensitivity and glucose usage leaving more for the fetus

Hormones of Pregnancy Relaxin Aldosterone secretion rises
↑ during pregnancy and allows ligaments to “relax”  widening of pubic bones, facilitates labors (softens cervix) Aldosterone secretion rises fluid retention  mother’s blood volume Endocrine organs thyroid gland increases 50% in size  BMR of mother parathyroid glands enlarge stimulate osteoclasts to release additional calcium from mother’s bones Some women say their feet grow during pregnancy--- they were a size 8 before being pregnant and now are a size 8.5 or 9, it’s believed relaxin also relaxes other ligaments and tendons and women may become more flat footed b/c of this. woman’s pituitary gland grows about 50% larger during pregnancy produces markedly elevated levels of thyrotropin, prolactin, and ACTH thyroid gland becomes 50% larger under influence of HCG, pituitary thyrotropin, and human chorionic thyrotropin from placenta increases metabolic rate of mother and fetus parathyroid glands enlarge and increase osteoclast activity ACTH stimulates glucocorticoid secretion serve primarily to mobilize amino acids for fetal protein synthesis aldosterone secretion rises promoting fluid retention increasing mother’s blood volume relaxin, secreted by corpus luteum and placenta synergizes progesterone in stimulating the multiplication of decidual cells promotes growth of blood vessels in the pregnant uterus

Hormone Levels and Pregnancy

Adjustments to Pregnancy
B/c organs are displaced digestion is slower and heartburn may result… gravid women also urinate more frequently b/c of the pressure exerted on the bladder…. They also experience lower back or hip pain--- blood flow is often limited so swelling of the ankles occurs usually in the 3rd trimester, sitting indian-style aka tailor sitting, will stretch the sartorius muscle and allow the femoral artery and vein more room and blood flows easier.

Digestive System nausea first few months constipation and heartburn due to  intestinal motility pressure on stomach Metabolism BMR  may stimulate appetite healthy weight gain - 24 lb. digestive system morning sickness – nausea especially arising from bed in the first few months of gestation unknown cause constipation and heartburn due to: reduced intestinal motility pressure on stomach causing reflux of gastric contents into the esophagus metabolism basal metabolic rate (BMR) – rises about 15% in second half of gestation appetite may be strongly stimulated healthy average weight gain – 24 lbs.

Nutrition placenta stores nutrients for 3rd trimester protein, iron, calcium, phosphates vitamin K reduces risk of hemorrhages in neonatal brain folic acid prevent neurological disorders spina bifida, anencephaly supplements must be started before pregnancy nutrition placenta stores nutrients in early gestation and releases them in the last trimester demand especially high for protein, iron, calcium, and phosphates needs extra iron during late pregnancy or will become anemic vitamin K given in late pregnancy to promote prothrombin synthesis in the fetus minimizes risk of neonatal hemorrhage especially in the brain vitamin D supplements help insure adequate calcium absorption to meet fetal demand folic acid reduces the risk of neurological fetal disorders spina bifida, anencephaly supplements must be started before pregnancy

Circulatory System mother’s blood volume and cardiac output - rises 30% due to fluid retention and hemopoiesis by full term, placenta requires 625 mL of blood/minute hemorrhoids and varicose veins from pressure on large pelvic blood vessels circulatory system by full term, placenta requires 625 mL of blood per minute from the mother mother’s blood volume rises about 30% during pregnancy due to fluid retention and hemopoiesis mother has about 1 to 2 L of extra blood mother’s cardiac output rises 30% to 40% above normal by week 27 falls almost to normal during the last 8 weeks pregnant uterus puts pressure on large pelvic blood vessels that interferes with venous return from the legs can result in hemorrhoids, varicose veins, and edema of the feet

Respiratory System minute ventilation  about 50% demands of fetus, higher maternal metabolic rate ventilation adjusted to keep PCO2 lower than normal respiratory rate  difficult to breathe deeply respiratory system respiratory rate remains constant tidal volume and minute ventilation increases about 40% two reasons for this: oxygen demand rises in proportion to the woman’s increase in metabolic rate and the increasing needs of the fetus progesterone increases the sensitivity of the woman’s chemoreceptors to carbon dioxide ventilation is adjusted to keep her arterial Pco2 lower than normal promotes CO2 diffusion from fetal blood stream into maternal blood ‘air hungry’ from pressure on the diaphragm from growing uterus breathes more easily in the last month due to pelvic expansion causing the fetus to drop lower in the pelvic cavity taking pressure off the diaphragm

Urinary System salt and water retention due to aldosterone and steroids GFR  by 50% and output is slightly elevated mother disposes additional metabolic wastes  frequency of urination due to bladder compression urinary system aldosterone and the steroids of pregnancy promote water and salt retention by the kidneys glomerular filtration rate increases 50% and urine output is slightly elevated enables the woman to dispose of both her own and the fetus’s metabolic wastes pregnant uterus compresses the bladder and reduces its capacity frequent urination and uncontrollable leakage of urine (incontinence)

Integumentary Systems stretch marks due to dermal stretching linea alba may become dark (linea nigra) temporary chloasma or “mask of pregnancy” blotchy darkening of skin over nose and cheeks integumentary system skin grows to accommodate expansion of the abdomen and breasts added fat deposition in hips and thighs striae or stretch marks can result from tearing the stretched connective tissue reddish at first, but fade after pregnancy melanocyte activity increases in some areas darkening of the areolae and linea alba (linea nigra) temporary blotchy darkening of the skin over the nose and cheeks ‘mask of pregnancy’ or chloasma disappears after pregnancy

Uterine Growth and Weight Gain
uterus weighs about 50 g when not pregnant weighs about 900 g at the end of pregnancy reaches almost to the xiphoid process

Childbirth - Uterine Contractility
Parturition process of giving birth by contraction of uterine and abdominal muscles Braxton Hicks contractions throughout gestation strengthen late in pregnancy - false labor in the seventh month of gestation, the fetus normally turns into the head-down vertex position most babies born head first head acting as a wedge that widens the mother’s cervix, vagina, and vulva during birth fetus is a passive player in its own birth expulsion achieved by contractions of mother’s uterine and abdominal muscles fetus may play a role chemically by stimulating labor contractions sending chemical messages that signify when it is developed enough to be born Braxton Hicks contractions – relatively weak contractions of the uterus over the course of gestation strengthen late in pregnancy - false labor contractions transform suddenly into more powerful labor contractions parturition - the process of giving birth marked by the onset of true labor contractions progesterone and estradiol balance may be one factor in this pattern of increasing contractility progesterone inhibits uterine contractions, but declines after 6 months estradiol stimulates uterine contractions, and continues to rise

Childbirth - Uterine Contractility
Progesterone inhibits contractions Estrogen stimulates contractions Near full term - posterior pituitary releases more oxytocin, uterus produces more receptors directly stimulates myometrial contractions stimulates fetal membranes to produce prostaglandins - synergists of oxytocin Stretching increases contractility of smooth muscle role in initiating labor as pregnancy nears full term - posterior pituitary releases more oxytocin (OT), uterus produces more OT receptors oxytocin promotes labor in two ways: directly stimulates muscles of myometrium stimulates fetal membranes to produce prostaglandins, which are synergists of oxytocin in producing labor contractions conceptus may produce chemical stimuli promoting its own birth fetal cortisol rises and may increase estrogen secretion by the placenta fetal pituitary produces oxytocin, but may stimulate fetal membranes to produce prostaglandin uterine stretching thought to play a role in initiating labor stretching of smooth muscle increases contractility of smooth muscle role in initiating labor

Labor Contractions Contractions begin 30 minutes apart and eventually occur every 1-3 minutes periodically relax to  blood flow to placenta and fetus contractions strongest in fundus and body of uterus, pushes fetus into cervix labor contractions begin about 30 minutes apart and eventually occur every 1 to 3 minutes periodically relax to increase blood flow and oxygen delivery to placenta and fetus contractions strongest in fundus and body of uterus weakest in the cervix pushes fetus downward positive feedback theory of labor labor induced by stretching of cervix triggers a reflex contraction of the uterine body pushes the fetus downward stretches the cervix even more self-amplifying cycle of stretch and contraction

Labor Contractions Self-amplifying cycle of stretch and contraction
positive feedback cycles increase contractions cervical stretching  oxytocin secretion  uterine contraction  repeat reflex arc from uterus  spinal cord  abdominal skeletal muscles cervical stretching induces a neuroendocrine reflex through the spinal cord, hypothalamus, and the posterior pituitary posterior pituitary releases oxytocin carried by the blood and stimulates uterine muscles directly and through the action of prostaglandin cervical stretching → oxytocin secretion → uterine contraction →cervical stretching woman feels need to “bear down” contraction of these muscles aids in expelling the fetus especially when combined with the Valsalva maneuver for increasing intra-abdominal pressure

Pain of Labor Ischemia of myometrium
Stretching of cervix, vagina and perineum episiotomy prevents tearing Large fetal head in a narrow pelvic outlet pain of labor is due at first mainly to ischemia of the myometrium muscles hurt when they are deprived of blood each contraction temporarily restricts uterine circulation as fetus enters the vaginal canal, the pain becomes stronger stretching of the cervix, vagina, and perineum sometimes tearing of the vaginal tissue episiotomy may be necessary – an incision in the vulva to widen the vaginal orifice to prevent random tearing pain an evolutionary product of two factors: unusually large brain and head of the human infant narrowing of the pelvic outlet which helped humans adapt to bipedal locomotion

Stages of Labor labor occurs in three stages:
dilation expulsion placental stage duration of each stage tends to be longer in primipara woman giving birth for the first time than in multipara woman who has previously given birth

Stages of Labor -- Early Dilation
longest stage – lasting 8 to 24 hours dilation of cervical canal and effacement (thinning) of cervix to reach 10 cm - diameter of fetal head rupture of fetal membranes and loss of amniotic fluid “breaking of the waters” Widening of cervical canal by effacement (thinning) of cervix to reach 10 cm -- diameter of fetal head Rupture of fetal membranes and loss of amniotic fluid

Stages of Labor -- Late Dilation
dilation reaches 10 cm in 24 hours or less in primipara (first baby) and in as little as few minutes in multipara Dilation reaches 10 cm in 24 hours or less in primipara (first baby) and in as little as few minutes in multipara

Stages of Labor -- Expulsion
begins when the baby’s head enters vagina lasts until the baby is expelled up to 30 minutes crowning – when the baby’s head is visible delivery of the head is the most difficult part nose and mouth suctioned before delivery to clear airway after expulsion, attendant drains blood from umbilical vein into baby clamps umbilical cord in two places, and cuts cord between clamps Time baby’s head enters vagina until delivery up to 30 minutes Valsalva maneuver helps to expel fetus

Stages of Labor -- Placental
uterine contractions continue causing placental separation membranes (afterbirth) inspected to be sure everything has been expelled Uterine contractions continue causing placental separation

Crowning (Expulsion Stage)

Expulsion Stage (cont.)

Placental Stage

C-sections Birth via c-section (cesarean section) has dramatically increased over the last 10 yrs. It is usually performed b/c there are health risks to mother and/or child if a natural delivery occurs. The picture here shows a c-section in progress of a breeched baby. The majority of c-sections today consist of an incision through the abdomen and uterus. This incision is usually a horizontal one, unlike the longitudinal or vertical ones of the past… The horizontal incision is often referred to as a bikini cut due to its location. C-section is a major surgery and does require a longer recovery period than that of a natural birth; however, there are plenty of reasons for a women to choose this route of delivery as a safer method such as: Failure to dilate during a prolonged labor or labor never begins, fetal distress (his heart beat is abnormal or has stopped), maternal distress (often to due to long labors and the mother is tired and may be unable to push), uterine rupture (this occurs in about 1 out of 300 of post-c-section pregnancies when the mother has decided to try a natural birth after having a previous child via c-section), High Risk fetus or multiple births, complications due to infant size (if the mother has gestational diabetes the infant is usually over 8 lbs making a vaginal delivery more difficult) or complications b/c the mother has pre-eclampsia, high blood pressure, active herpes or another STD that could harm the infant via vaginal birth. Emergency c-sections are also common… this may occur b/c labor has not progressed, the fetus is in distress, or if the mother has a temperature over 100 then some type of infection has probably occurred (that’s another reason why nurses and doctors do not check the cervix multiple times an hour--- everytime cervix dilation is checked the possibly of introducing bacteria to the area increases, which increases the likelihood of infection).

Puerperium First 6 weeks after delivery
Anatomy and physiology return to normal involution of uterus to pre-gravid weight in 4 weeks accomplished by autolysis by lysosomal enzymes vaginal discharge called lochia breastfeeding promotes involution suppresses estrogen secretion stimulates oxytocin which causes myometrial contraction first 6 weeks postpartum (after birth) are called the puerperium period in which the mother’s anatomy and physiology stabilize and the reproductive organs return nearly to the pregravid state (condition prior to pregnancy) involution – shrinkage of the uterus loses 50% of its weight in the first week involution is achieved by autolysis (self-digestion) of uterine cells by their own lysosomal enzymes for about 10 days produces a vaginal discharge – lochia bloody at first and then turns serous breast-feeding promotes involution suppresses estrogen secretion which would make the uterus more flaccid stimulates oxytocin secretion which causes myometrium to contract and firm up the uterus sooner

Mammary Gland Development
Lactation synthesis and ejection of milk from mammary glands in breast Ducts grow and branch due to high estrogen levels in pregnancy Followed by budding and development of acini at the ends of the ducts due to progesterone lactation – the synthesis and ejection of milk from the mammary glands lasts as little as a week in women who do not breast-feed their infants can continue for many years as long as the breast is stimulated by a nursing infant or a mechanical device (breast pump) women traditionally nurse their infants until a median age of about 2.8 years high estrogen level in pregnancy causes the ducts of the mammary glands to grow and branch extensively growth hormone, insulin, glucocorticoids, and prolactin contribute to this development progesterone stimulates the budding and development of acini at the end of the ducts acini organized into grape-like clusters (lobules) within each breast lobe

Colostrum and Milk Synthesis
Colostrum forms in late pregnancy similar to breast milk; contains 1/3 less fat, thinner first 1 to 3 days after birth contains IgA protection from gastroenteritis Synthesis is promoted by prolactin (from pituitary) synthesis of hormone begins 5 weeks into pregnancy, by full term it is 20x normal level steroid hormones from placenta oppose it until birth colostrum forms in late pregnancy similar to breast milk in protein and lactose, but contains 1/3 less fat first 1 to 3 days after birth thin watery consistency and a cloudy yellow color contains IgA to protection the baby from gastroenteritis prolactin (from anterior pituitary) promotes milk synthesis inhibited by dopamine when not pregnant synthesis of hormone begins 5 weeks into pregnancy, by full term it is 10 to 20 times normal level little effect on mammary glands until after birth steroid hormones from placenta oppose prolactin until birth milk synthesis also requires growth hormone, cortisol, insulin, and parathyroid hormone to mobilize necessary amino acids, fatty acids, glucose, and calcium

Colostrum and Milk Synthesis
At birth, prolactin secretion drops, but  20 times after nursing without nursing, milk production stops in 1 week 5-10% of women become pregnant while nursing inhibition of GnRH and reduced ovarian cycling at birth, prolactin secretion drops to nonpregnancy levels every time the infant nurses prolactin levels jump to 10 to 20 times this level for the next hour stimulates the synthesis of milk for the next feeding without nursing, milk production stops in 1 week only 5-10% of women become pregnant while breast-feeding inhibition of GnRH and reduced ovarian cycling natural means of spacing births

Prolactin and Lactation

Milk Ejection Controlled by a neuroendocrine reflex
infant’s suckling stimulates sensory receptors in nipple, signaling hypothalamus and posterior pituitary to release oxytocin oxytocin stimulates myoepithelial cells Myoepithelial cells surround secretory cells in acinus contract to squeeze milk into duct milk flow within seconds after suckling begins milk is continually secreted into the mammary acini, but does not easily flow into the ducts milk ejection (letdown) is controlled by a neuroendocrine reflex infant’s suckling stimulates sensory receptors in nipple, signaling hypothalamus and posterior pituitary to release oxytocin oxytocin stimulates myoepithelial cells around each acinus contract to squeeze milk into duct milk flow within seconds after suckling begins

Breast Milk Supplies antibodies and colonizes intestine with beneficial bacteria Colostrum and milk have a laxative effect that clears intestine of meconium (green, bile-filled fecal material in newborn) Nursing woman can produce 1.5L per day Cow’s milk not a good substitute 1/3 less lactose but 3 times as much protein harder to digest and more nitrogenous waste (diaper rash) breast milk changes composition over the first two weeks varies from one time of day to another at the end of a feeding there is less lactose and protein, but six times the fat cow’s milk not a good substitute 1/3 less lactose but 3 times as much protein harder to digest and more nitrogenous waste (diaper rash) colostrum and milk have a laxative effect that clears intestine of meconium (green, bile-filled fecal material in newborn) supplies antibodies and colonizes intestine with beneficial bacteria nursing woman can produce 1.5L per day

Contraceptive Devices
These are just a few of the current birth control methods.

Methods of Contraception
contraception - any procedure or device intended to prevent pregnancy behavioral methods abstinence rhythm method (periodic abstinence) withdrawal (coitus interruptus) barrier and spermicidal methods male and female condom, diaphragm, sponge hormonal methods “the pill”, patch, injection or vaginal ring - ovarian follicles do not mature “morning after pills” – induces menstruation providing implantation has not occurred RU-486 – induces abortion up to 2 months into pregnancy preventing implantation intrauterine device (IUD) surgical sterilization clamping or cutting the genital ducts (uterine tubes or ductus deferens)

The Female Reproductive System Jen Tynes SELU

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