The placenta develops from the trophoblast layers of the fertilized egg and connects the developing fetus to the uterine wall. It allows for nutrient and gas exchange between the mother and fetus's blood supply. The placenta grows throughout pregnancy and is fully developed by the end of the first trimester. It has both a maternal and fetal surface and connects to the fetus via the umbilical cord. The placenta functions to provide nutrition, gas exchange, waste removal, hormone production, storage, and protection for the fetus. Abnormalities like placenta accreta, increta, percreta, previa and abruptio placentae can complicate delivery and cause hemorrhaging. The placent

2. placenta

3. Out line:
Introduction
Definition of placenta
Development of the placenta
Structure and characters of placenta
Function of placenta
Circulation
Abnormalities
Delivery of placenta
Nursing role

4. :
Introduction
The placenta originating from the
trophoblast layers of the fertilized ovum it
self .it links closely with the mothers
circulation to carry out functions which the
fetus is unable to perform for itself during
intrauterine life .the survival of the fetus
depends upon its integrity and efficiency .

5. Definition:
The placenta is an organ that connects the developing fetus
to the uterine wall to
Allow nutrient uptake, waste elimination, and gas exchange
via the mother's blood supply.

6. Development:
•The placenta begins to develop upon implantation of the
blastocyst into the maternal endometrium.
• The outer layer of the blastocyst becomes the trophoblast,
which forms the outer layer of the placenta. This outer layer
is divided into two further layers
•The placenta grows throughout pregnancy. Development of
the maternal blood supply to the placenta is complete by the
end of the first trimester of pregnancy (approximately 12–13
weeks).

8. Structure and characters:
Maternal surface
*
Fetal surface
*
*The fetal sac
Outer membrane(chorion)
Inner membrane(amnion)
In humans, the placenta averages 22 cm in length and 2–
2.5 cm in thickness it typically weighs approximately
500 grams. It has a dark reddish-blue or maroon color.
It connects to the fetus by an umbilical cord of
approximately 55–60 cm in length that contains two arteries
and one vein.

10. Function of placenta:
A) Nutrition and immunity:
The perfusion of the intervillous spaces of the placenta with
maternal blood allows the transfer of nutrients and oxygen
from the mother to the fetus and the transfer of waste
products and carbon dioxide back from the fetus to the
maternal blood supply.
IgG antibodies can pass through the human placenta, thereby
providing protection to the fetus in utero

11. B) Endocrine function:
In humans, aside from serving as the conduit for oxygen and
nutrients for fetus, the placenta secretes hormones that are
important during pregnancy.
Hormones:
Human Chorionic Gonadotropin (HCG): The first placental
hormone produced is HCG, which can be found in maternal
blood and urine as early as the first missed menstrual period
through about the 100th day of pregnancy.
. HCG also ensures that the corpus luteum continues to
secrete progesterone and estrogen. Progesterone is very
important during pregnancy because, when its secretion
decreases, the endometrial lining will slough off and
pregnancy will be lost. HCG suppresses the maternal
immunologic response so that placenta is not rejected.

12. Human Placental Lactogen (hPL): This hormone is lactogenic
and growth-promoting properties. It promotes mammary
gland growth in preparation for lactation in the mother. It also
regulates maternal glucose, protein, and fat levels so that this
is always available to the fetus.
Estrogen is referred as the "hormone of women" because it
stimulates the development of secondary female sex
characteristics. It coto ntributes to the woman's mammary
gland development in preparation for lactation and stimulates
uterine growth to accommodate growing fetus.
Progesterone is necessary to maintain endometrial lining of
the uterus during pregnancy. This hormone prevents preterm
labor by reducing myometrial contraction. Levels of
progesterone are high during pregnancy.

13. C) Storage:
The placenta metabolizes glucose that is stored in the form of
glucose and reconverts it to glucose as required.
The placenta can also store iron and fat soluble vitamins.
D) Excretion:
-The main substance excreted from the fetus is carbon
dioxide.
Amount of urea and uric acid excreted are very small.
Billirubin will also be excreted.
E) Protection:
Placenta provide limited barrier to infection but few bacteria
cross early and may be causes congenital anomalies.

14. Maternal blood fills the intervillous space, nutrients, water,
and gases are actively and passively exchanged, then
deoxygenated blood is displaced by the next maternal pulse.
Placental circulation:

15. Maternal placental circulation:
-In preparation for implantation, the uterine endometrium
undergoes 'decidualisation'. Spiral arteries in decidua are
remodeled so that they become less convoluted and their
diameter is increased. The increased diameter and straighter flow
path both act to increase maternal blood flow to the placenta.
- The relatively high pressure as the maternal blood fills
intervillous space through these spiral arteries bathes the fetal villi
in blood, allowing an exchange of gases to take place.
- In humans and other he comes into direct contact with the fetal
chorion, though no fluid is exchanged.
-As the pressure decreases between pulses, the deoxygenated
blood flows back through the endometrial veins.
Maternal blood flow is approx 600–700 ml/min at term.

16. Fetoplacental circulation:
-Deoxygenated fetal blood passes through umbilical arteries
to the placenta. At the junction of umbilical cord and
placenta, the umbilical arteries branch radially to form
chorionic arteries.
- Chorionic arteries, in turn, branch into cotyledon arteries. In
the villi, these vessels eventually branch to form an extensive
arterio-capillary-venous system, bringing the fetal blood
extremely close to the maternal blood; but no intermingling
of fetal and maternal blood occurs ("placental barrier").
-Endothelin and prostanoids cause vasoconstriction in
placental arteries, while nitric oxide vasodilation. On the
other hand, there is no neural vascular regulation, and
catecholamines have only little effect.
mochorial placentals, the maternal blood.

17. Abnormalities:
Placenta accrete:
-Occurs when the placenta attaches too deep in the uterine
wall but it does not penetrate the uterine muscle.
It is the most common type 75% of cases.
Placenta increta:
-Occurs when the placenta attaches even deeper into the
uterine wall and does peneterate into the uterine muscle.
It accounts 15% of all cases.
Placenta percreta:
-Occurs when placeta peneterate through the entire uterine
wall and attaches to another organ such as bladder.
It accounts 5% of all cases .
complication:
-Abnormal adherent to uterine wall may lead to delay
separation or post partum hemorrhage.

19. Placenta previa :
-Placenta is partially or completely implanted in the lower
uterine segment.
Complication:
-it places the mother and fetus as high risk as it causes
placenta to separate and severe bleeding can occur .
.

20. abruptio placenta:
premature separation of the placenta from anormally implanted site
occurring after 28th week of pregnancy .
complication :
dissemination intra vascular coagulation.
Post partum hemorrhage

21. Delivery of the placenta:
-as the placenta delivers ,hold it in both hands and gently
turn it until the membranes are twisted .
-slowly pull to complete the delivery . move membranes up
and down until they deliver .
-if the membranes tear ,gently examine the upper vagina and
cervix wearing sterile gloves and use a sponge forceps to
remove any remaining pieces of membrane.
-place the placenta in the receptacle provided (for later
examination).

23. Nursing role:
-hold the placenta in the palm of the hands,with maternal side
facing upword.
-check whether all of the lobules are present and fit together.
-hold the cord with one hand and allow the placenta and
membranes to hang down.
-insert the other hand inside the membranes, with fingers
spread out.
-inspect the membranes for completeness.
-if membranes or placenta are not complete, take immediate
action.
-document the findings in the delivery room report.

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