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VI. ANATOMY AND PHYSIOLOGY
EXTERNAL STRUCTURE
Mons veneris/mons pubis
pad of adipose tissue located over the symphysis pubis, protect the junction of the
pubic bone from trauma.
Labia Majora
2folds of adipose tissues, encloses the region called “Vestibule”.
Labia Minora
Posterior to the mons pubis, two hairless folds of connective tissue, abundant with
sebaceous gland and its product is “SEBUM” lubricant that keeps the skin soft and
moist.
Vestibule
Flattened smooth surface inside the labia, opening to the bladder (urethra) and the
uterus (vagina) both arises from the vestibule.
Clitoris
1-2cm rounded organ of erectile tissue at the forward junction of the labia minora it is
covered by a fold of skin called “Prepuce”.
Sensitive to touch and to temperature and center of sexual arousal and orgasm in
woman.
Skene’s Gland (Paraurethral Gland)
Lateral to urinary meatus, ducts open to the urethra.
Bartholin’s Gland (Vulvovaginal Gland)
Lateral to vaginal opening both side
Their secretion helps to lubricate the external genitalia during intercourse. Both
glands may become infected and produce a discharge and local pain.
The alkaline ph of their secretions helps to improve sperm survival in the vagina.
Fourchette
Ridge of tissue formed by the posterior joining of the labia’s.
Episiotomy is done on this part to enlarge the vaginal opening for the passageway of
the fetus.
Hymen
Tough and elastic semicircle of the tissue.
Covers the opening of the vagina.
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Perineum
Diamond shape region between the anterior end of the labial fold and the anus
posteriorly.
Anus
Distal end of the digestive tract, the outlet of the rectum.
INTERNAL STRUCTURE
Fallopian tube
Arise from each upper corner of the uterine body , extend outward and backward until
each opens at its distal end next to an ovary.
10cm long, conveys ovum from the ovaries to the uterus and to provide a place for
fertilization of the ovum by sperm.
4PARTS:
1. Interstitial
Most proximal division, 1 cm in length, 1mm in Diameter.
Where ectopic pregnancy occur.
2. Isthmus
Cut or scaled in tubular ligation or tubal sterilization.
3. Ampulla
Longest portion 5cm long.
Fertilization of ovum usually occurs in here.
4. Infundibulum
Have fimbrae (small hairs) that helps to guide the ovum into fallopian
tube.
Vagina
Allows passage of menstrual flow.
Receives penis during intercourse.
Lower portion of birth canal during delivery.
Cervix
Neck of the uterus, separates upper end of the vagina from the isthmus of the uterus.
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Uterus
Pear shaped muscular organ that has three components the corpus (body), cervix
(neck), fundus.
Broad ligament/round ligament is the fibrous muscular cords that steady the uterus.
3 LAYERS
Endometrium
- Inner layer, where implantation of embryo occur.
Myometrium
- bulky middle of the uterus
- plays important role in delivery to contract rhythmically
- to force the body out.
Perimetrium
- outermost serious layer of the uterus.
Ovary
Grayish white, almond shaped female gonads.
Produce mature and discharged ova.
Maturation and maintenance of sex characteristics.
PRODUCTION OF OVUM
Ovary reveals tiny sack like structures called “Ovarian/Primary Follicle”.
Each follicle consists of an immature egg “Oocyte”.
Surrounded by one or more layers of very different cells “Follicle Cell”.
As the egg developed, follicle begins to ripen/mature.
Follicle enlarges and develops a fluid filled central region called “Antrum” also called
“Vesicular/Graafian Follicle” and developing egg is ready to be ejected from the
ovary an event called “Ovulation”.
Ruptured follicle is transformed into a very small structure called “Corpus Luteum”,
“Corpus Albican”.
MENSTRUATION – Episodic uterine bleeding in response to cyclic hormonal
changes.
FOLLICLE STIMULATING HORMONE
Stimulates ovary to produce Estrogen
Follicle development of ovary
Oocyte maturation
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Graafian follicle maturation
Stimulates in increasing the amount of endometrial activity during luteal phase.
LEUTINIZING HORMONE
Triggers ovulation of egg
Rupture follicle to produce Progesterone, Estrogen
PROGESTERONE
Hormone of mothers
Necessary to maintain the endometrial lining of the uterus during pregnancy.
Present in serum as early as 4th week of pregnancy as a result of continuation of
Corpus Luteum.
After placental synthesis begins at about 12th week, level of progesterone rises
progressively during the remainder of pregnancy.
Reduce the contractility of uterus during pregnancy, preventing premature labor.
Reduce contractility is produced by a change in electrolytes (notably potassium and
calcium), which decreases the contraction potential of the uterus.
Progesterone withdrawal due to menstruation.
Hormone for the stimulation of gall bladder.
ESTROGEN
Primarily ESTRIOL is produced as a second product of the syncytial cells of the
placenta.
Contributes to the woman mammary gland development in preparation for lactation
and stimulates uterine growth to accommodate the developing fetus.
Development of uterus, fallopian tube, vagina, and the development of the secondary
sex characteristics.
PROSTAGLANDIN
Mediator of pain
Secondary to the contraction of the lining of the uterus stimulating muscle to contract.
INITIATION OF MENSTRUATION
Hypothalamus is the main initiator of menstruation.
Release of Gonadotrophic releasing hormone (leutinizing hormone releasing
hormone) by the hypothalamus.
Hypothalamus stimulates the menstrual cycle
During childhood hypothalamus is very sensitive to high amount of estrogen
produced by the adrenal gland that release of hormone is suppressed.
During puberty hypothalamus is less sensitive to estrogen and feedback mechanism
occur, GnRH is transmitted from hypothalamus to AnPG to stimulate the release of
estrogen and progesterone, menstruation then occurs.
PHASES OF MENSTRUATION
MENSTRUAL PHASE
Last for five days, decrease estrogen, 28-32 days(R), 22-44(IR)
Stimulates the Hypothalamus
Signals the Anterior Pituitary Gland to release Gonadotrophic hormone
Stimulating the release of Follicle Stimulating Hormone and Leutinizing
Hormone
Follicle Stimulating Hormone stimulates ovary to develop ovarian follicle
secreting high amount of estrogen
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Negative feedback mechanism goes to hypothalamus
Suppressing the follicle stimulating hormone
Leutinizing hormone acts to enhance Corpus Luteum Formation
PROLIFERATIVE PHASE
Increase in FSH, Estrogen, 6-14 days
1-8 fold of endomertium.
Increase in follicular phase
Primordial follicle stimulates ovarian follicle forming CLF
Ovarian response phases
Follicle maturation response to FSH stimulation
CLF stimulates to develop from secondary/rupture follicle
Increase in FSH,estrogen
SECRETORY PHASE
Increase in vascularity of endometrium
15-26 days
After the ovum was released it is rupture in the form of CLF
Endometrium lining thickens continuously
Increase in capillary supply
Skimming phase (no fertilization)
Increase in progesterone, LH/CLF regress
Follicle matured
CNS decrease Estrogen and Progesterone
ISCHEMIC PHASE
27-28 days
Regression of corpus luteum formation
↓progesterone, ↓estrogen
Constriction of artery of endometrium
Increase in secretion of prostaglandins
No fertailization(skimming phase)
Endometrium shed of ruptured
Menstruation begins
EPISIOTOMY
Surgical incision of the perineum that is made both to prevent tearing of the
perineum and to release pressure of the fetal head.
EPISIORAPHY
Is the repair of the perineum through stitches an d with the use of chromic suture.
TYPES :
MER (Median episiotomy repair)
heal more easily
less blood loss
less postpartal discomfort
RMLER (Right medio lateral episiotomy repair)
more on bleeding
intense pain
away from rectum, less complications
DEGREES OF LACERATION
1st degree
o small laceration, no stitches are required
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2nd degrees
o laceration deep into the muscle, underneath
3rd degree
o tear in the vaginal tissue
o perineal skin/muscle that extend to the anal sphincter
4th degree
o to the sphincter, tissue underneath
o tear of the top of the vagina near the urethra/ paraurethral laceration.
PLACENTA
Latin “pancake” arises out of the continuing growth of trophoblast tissue.
15-20cm in diameter 2-3 cm in depth covering about half the surface area of the
internal uterus at term.
Role is it serves as a respiratory, excretory, and nutrition delivery system for the
fetus.
It produces several protein and steroid hormones that help maintain pregnancy and
pave the way for the delivery of the baby.
It also produces a hormone called hCG( human chorionic gonadotropin).
100 maternal uterine artery supply the mature placenta to provide enough blood for
exchange.
Woman lies on her left side to lift the uterus away the inferior vena cava. Placental
circulation can be so sharply reduced to supine hypotension, if the women lies on her
back and the weight of the uterus compresses the vena cava.
Placenta weighs about 400-600g (1lb); containing 20-30 cotyledons.
RELAXIN
one of placental hormone causes mothers pelvic ligaments and the symphysis to
relax and become more flexible which eases birth passage.
CHORIONIC VILLI
Once implantation is complete, Trophoblastic layer of cells of the Blastocyst begins
to mature rapidly.
11th-12th day miniature villi that resemble proving fingers termed to be called as
CHORIONIC VILLI.
At term 200 villi will have formed.
2LAYER:
SYNCYTIOTROPHOBLAST
▪ or the syncytial layer, the outer layer,
▪ produce placental hormone such as Hcg, Hpl, estrogen, progesterone.
CYTOTROPHOBLAST
▪ Langhan’s layer, present as early as 12 days gestation.
▪ to protect the embryo and fetus from certain infectious organisms
Such as the spirochete of syphilis.
SIGNS OF PLACENTAL SEPARATION
1. Lengthening of the cord
2. Sudden gush of vaginal blood
3. Change in the size of the uterus (Calkin’s sign)
4. Rise of the fundus in the abdomen
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PLACENTAL SEPERATION
Schultze presentation
- shiny, seperates first at its center and last at its ends
Dunkan presentation
- placenta seperates first at its edge, bloody maternal signs
BREAST
mammary glands form from ectodermic tissue early in utero
ACINAR cell where milk is deposited.
LACTIFEROUS DUCTS it is the passageway of the milk.
Nipple has 20-30 small opening through which milk is secreted.
AMPULLA portion of duct located just posterior to the nipple serves as a reservoir
for milk before breast feeding.
AREOLA is the skin surrounding the nipples, a dark pigmentation.
MONTGOMERY’S TUBERCLE– area appears rough on surface, sebaceous glands.
LACTATING is the production of milk.
TYPES OF MILK
1. NEONATAL MILK (WITCH MILK)
2. COLUSTRUM (contains antibody)
3. HIND MILK (after let down reflex)
HUMAN PLACENTAL LACTOGEN
Human Chorionic Somatomammotropin
Hormone with both growth-promoting and lactogenic (milk-producing) properties.
Produced by the placenta, beginning as early as the 6th week of pregnancy, ↑ to a peak
level at term. It can be assayed in both maternal serum and urine.
Promotes mammary gland (breast) growth in preparation for lactation in the mother.
Important role is by regulating maternal glucose, protein, and fat levels so that
adequate amounts of these nutrients are always available to the fetus.
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PROLACTIN
With the delivery of the placenta,↓ progesterone, dramatically stimulating
“PROLACTIN” an AnPG hormone.
Acts on the Acinar cells of the mammary glands to stimulate the production of milk.
When an infant sucks at the breast, nerve impulses travel from the nipple to the
hypothalamus to stimulate the production of “PROLACTIN – RELEASING
FACTOR.”
This stimulates further active production of Prolactin.
Othrer anterior thyroid stimulating hormone and growth hormone probably also play
a role in growth of the mammary glands and their ability to secrete milk.
CHLOASMA
Extra pigment on the face that occurs from “MELANOCYTE- STIMULATING
HORMONE”. Which might accompany pregnancy.
AMNIOTIC MEMBRANE
Smooth chorion. Outermost fetal membrane.
Form the sac that contains the amniotic fluid.
Forms beneath the chorion, to produce the fluid, support fluid.
AMNIOTIC FLUID
Shield fetus against pressure or a blow to the mother’s abdomen.
Protects fetus from changes in temperature.
Aids in muscular development, allows freedom of fetus to move.
Helps baby’s lung grow and develops because baby breathes in fluid.
Helps baby’s digestive system develop because baby swallow fluid.
Protects umbilical cord from pressure, protecting the fetal oxygen supply.
Fluid is slightly alkaline with a Ph of about 7.2.
800-1200 ml.
Clear and transparent in color
It contains electrolyte, minerals, vitamins, proteins, hormone and antibodies.
Human growth hormone, human follicle stimulating hormone, human leutinizing
hormone, human chorionic gonadotropin, thyroid hormone, insulin, glucagon,
testosterone, progesterone, estradiol, cortisone.
DECIDUA
Corpus luteum continues to atrophy because of Hcg hormone created by the
trophoblast cell. Causes uterine endometrium to continue to grow in thickness and
vascularity instead of sloughing off this is termed as the DECIDUA or the
discharged after giving birth.
▪ Decidua Basalis
o Lies directly under the embryo trophoblast portion is lied where communication
with the blood vessel and maternal occur.
▪ Decidua Capsularis
o Stretches or encapsulates the surface of the trophoblast..
▪ Decidua Vera
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o Remaining portion
HUMAN CHORIONIC GONADOTROPIN
Produced very early in pregnancy
Produced by the developing embryo and then by the fetal part of the placenta.
Stimulates ovary to continue producing estrogen and progesterone so that lining of
the uterus is not sloughed off.
Hormone that is secreted early in the first week of missed menstruation. Can be
detected with the use of pregnancy kit or test.