placenta

1. DR NILESH KATE
MBBS,MD
ASSOCIATE PROF
DEPT. OF PHYSIOLOGY
PLACENTA,
PARTURITION &
LACTATION

2. OBJECTIVIES
 Placenta –structure
 Functions of placenta
 Hormones of placenta
 Fetoplacental unit
 Parturition
 Stages of parturition
 Mechanism of
parturition.
 Lactation
 Stages of lactation

3. FERTILIZATION
 The genetic material
from a sperm cell
and secondary
Oocyte merges into a
single nucleus is
called fertilization.

4. IMPLANTATION
 About six days after
fertilization the
blastocyst attaches
to the endometrium
a process called
implantation

5. FERTILIZATION

6. PLACENTA
 After implantation a portion of the
endometrium becomes modified known as
decidua.
 The decidua basalis – Portion of endometium
between chorion and stratum basalis –
Maternal placenta
 The decidua capsularis – portion of the
endometrium covers the embryo located
between embryo and uterine cavity.
 The decidua parietalis – Non involved area of
endometrium

7. PLACENTA – MACROSCOPIC VIEW

8. PLACENTA
 It is formed by the union of
maternal decidua and foetal
chorionic villi and is
connected to the foetus by the
umbilical cord.
 Formed during the 6th
to 12th
weeks of pregnancy
 The fully developed placenta is
disc-shaped with a diameter of
15 to 20cm and thickness of 2-
5cm and weighs about 500gm.

9. PLACENTA
 There are numerous foetal
chorionic villi lined by trophoblast
cells.
 They contain foetal blood.
 In the intervillous spaces are the
maternal blood sinuses containing
maternal blood.
 In the placenta, maternal and foetal
blood come in contact, but do not
mix as they are separated by the
placental barrier.

10. WHY PLACENTA?
 The placenta is essential
for
A) Vital foetal functions
and
B) for maintaining
pregnancy

11. Functions of Placenta
Nutritive function:
Glucose, iron, calcium, phosphorus, aminoacids, water,NaCl , vitamins and
fatty acids
Excretory Function: Waste
products like urea, uric acid diffuse form foetal to maternal blood
Immunological function: The
foetus is antigenically a foreign body, the placenta protects the
embryoand foetus from rejection. The MHC class I and II are not present
on the placental trophoblast.
Barrier Function: Though
large molecular weight substances cannot cross the placenta
Respiratory Function: Exchange
of oxygen and CO2 between fetuse and mother. It is facilitated by three
factors: HbF, Large quantity of Hb, Double Bohr effect

12. Placenta - Functions
MOTHER
NUTRITION
OXYGEN
ANTIBODIES
HORMONES
PLACENTA FOETUS
CARBON
DIOXIDE
METABOLITES
STORAGE
PLACENTAL
HORMONES
BLOOD

13. ENDOCRINE FUNCTION
 Endocrine Function:
Placenta is the temporary endocrine organ of
pregnancy and synthesizes many hormones.
1. Oestrogen
2. Progesteron
3. HCG
4. HCS
5. Relaxin

14. OESTROGEN
 Oestrogens are synthesized in the
syncitiotrophoblast.
 Greatly increases blood flow to the
uterus, placenta and foetus.
 Stimulates the development of
ducts of breast gland.
 Increases the sensitivity to
oxytocin.
 Development and growth of
uterus,accessory sex organs.
 its concentration greatly increases
towards the end of pregnancy.

15. Progesterone Is synthesized in the
syncitiotrophoblast from maternal
cholesterol.
 Its concentration greatly increases
and reaches a peak towards the
end of pregnancy (up to 19
μg/100 ml)
 It is the hormone of pregnancy
 It suppresses ovulation and
menstruation
 inhibits uterine motility
 maintains pregnancy
 Increase the development of the
alveolar system of the mammary
gland

16. Human Chronic
Gonadotrophin
(HCG)
 Synthesized by
syncitiotrophoblast
 It maintains the corpus
luteum of pregnancy to
secrete estrogen and
progesterone
 stimulates foetal androgen
secretion.
 Stimulates the growth of
breast gland
 Helps for pregnancy
diagnosis tests.

17. HUMAN CHORIONIC
SOMATOMAMMOTROPHIN (HCS)
 Also human placental lactogen
(HPL) or chorionic growth hormone
– prolactin.
 It has lactogenic and growth
stimulating effects.
 begins about the 6th
week of
gestation peak by 36th
week (about
15 mg/ml).
 It promotes lipolysis, inhibits
gluconeogenesis and glucose
utilization.
 Favours retention of nitrogen,
calcium and phosphorous.
 It also has anti insulin effects.

19. FETO PLACENTAL UNIT
 The interaction between fetus and mother during synthesis of
steroid hormones called Feto- Placental Unit.
Urinary oestriol level is clinically used as an index of the health of the fetus

20. PARTURITION
 Parturition is a
process by which the
fetus, membranes
and placenta are
expelled from the
uterus
 It is also called
labour

21. INITIATION OF LABOUR
 At the end of about 40 weeks
of gestation, uterine
contractions begin. Initially
they are weak and painless
(Braxton –Hicks).
 Then the intermittent
contractions become painful
and increase in frequency,
duration and force, and the
cervix dilates

22. I - Stage of Labour
 From the beginning of
painful contractions of
the uterus to the full
dilatation of the cervix is
the first stage of labour.
 At this time the
membranes rupture and
amniotic fluid is
expelled.
 It last for about 16
hours.

23. II – Stage of Labor
 This stage begins with
complete dilatation of the
cervix.
 The foetus gradually passes
down the dilated canal by
merging of uterus, cervix and
vagina as a single broad
channel.
 Finally the foetus is delivered.
 Voluntary contraction of the
abdominal muscles and
diaphragm, and straining
assists in delivery.

24. III – Stage of Labor
 The expulsion of the
placenta which follows
a few minutes after the
delivery of foetus.
 Followed by delivery
there is beginning of
uterine contraction.

25. PLACENTA – AFTER
EXPULSION

26. POST CHANGES
 Following parturition, there is involution of the
uterus and pelvic organs.
 The postpartum period of six weeks is called
puerperium.
 However, it takes 3 months for the maternal
system to return to the pregravid state, and is
sometimes referred to as “fourth trimester”

27. Mechanism of Parturition
 At the end of pregnancy the uterus is greatly distended but the cervix
is soft.
 As labour begins, cervix dilates, afferent impulses travel up to the
hypothalamus, and increase oxytocin release.
 More glucocoritcoids with less andrgens –fall in progesterone
 Oxytocin acts directly on the uterine smooth muscles, and also by
increasing prostaglandin PGE2 formation
 Reduces formation of progesterone and increases oestrogens
(E/P) leads to increased production of prostaglandins.

28. Regulation of Parturition

30. LACTATION
Definition
 Process by which
milk secretion is
Initiated, maintained
and ejected Secreted
by mammary glands
Natural food of
newborns .

31. COMPOSITION
 Colostrum
 Fat – small globules
 Carbohydrate – Lactose
 Protein – Lactalbumin
- Lactoglobulin
- Lactoferrin, Lysozyme, Leukocytes
- Long chain W-3 Fatty acid
- IgA

32. STAGES OF LACTATION
 Mammogenesis
 Lactogenesis
 Galactokinesis
 Galactopoiesis

33. STAGES OF BREAST DEVELOPMENT
(Mammogenesis)
Up to Puberty: - Rudimentry
After Puberty : - Each menstrual cycle proliferation of lobulo – alveolar
system.
↑in duct system - Enlargement of Gland
Mammogenesis
Surface Epithelium invaginate
Invaginated column of cells become hollow
Hollow Solid columns of cells form duct & alveoli

34. LACTOGENESIS
From 5th
month of pregnancy there is small amount of
prolactin secretion.
Oestrogen & Progesterone suppress the ↑ activity of
prolactin.
At the time of parturition the oestrogen & progestrone
level ↓ & prolactin ↑.
 ↑ Secretion of breast milk.

35. GALACTOKINESIS (LET –DOWN
REFLEX)
- Neuro – Endocrine Reflex:
Suckling of baby
Impulses to hypothalamus
Relayed to neuro hypophysis
Release of oxytocin
Oxytocin to breast gland
Contraction of myoepithelial cells

36.  SUCKLING REFLEX
OR
 MYOEPITHELIAL
REFLX

37. GALACTOPOIESIS
Maintenance depends on
1.Hormones:
Prolactin - Helps in continuous secretion.
GH - Lactogenic Effect
Thyroxine - Metabolism in breast gland.
Cortisol - Permissive action.
2. Continuous Expulsion:
- Feeding & expulsion.
3. Nutrition
- ↑ quality of milk

38. Endocrine Control Of Breast Development
 Action of Progesterone:
↑ the size & number.
 Action of Prolactin:
↑ Alveoli growth by GH, Cortisol and
thyroxin.
 Growth Hormone: Growth of breast gland
Thyroid Hormone: Maintains Metabolic
activity maintains Normal growth.
 HCG & HPL : Stimulate growth of breast
gland.
 Insulin: Provides glucose for energy.

39. GALACTORREA
Hyper secretion of Milk:
- Physiological – in Newborns
- Drugs: (Galactogogues)
- Metoclopramide - Prolactin↑
- Sulpuride – Dopamine antagonist
Chiari – Frommel Syndrome:
Persistance of lactation and amenorrhea in women who do not
nurse after delivery
 This condition is called CHIARI – FROMMEL SYNDROME
Cause:
 Persistent prolactin secretion without the secretion of FSH and LH
necessary to produce maturation of new follicles and ovulation

40. STAGES OF LACTATION

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