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PLACENTA, PARTURITION AND LACTATION

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placenta

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PLACENTA, PARTURITION AND LACTATION

  1. 1. DR NILESH KATE MBBS,MD ASSOCIATE PROF DEPT. OF PHYSIOLOGY PLACENTA, PARTURITION & LACTATION
  2. 2. OBJECTIVIES  Placenta –structure  Functions of placenta  Hormones of placenta  Fetoplacental unit  Parturition  Stages of parturition  Mechanism of parturition.  Lactation  Stages of lactation
  3. 3. FERTILIZATION  The genetic material from a sperm cell and secondary Oocyte merges into a single nucleus is called fertilization.
  4. 4. IMPLANTATION  About six days after fertilization the blastocyst attaches to the endometrium a process called implantation
  5. 5. FERTILIZATION
  6. 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. 7. PLACENTA – MACROSCOPIC VIEW
  8. 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. 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. 10. WHY PLACENTA?  The placenta is essential for A) Vital foetal functions and B) for maintaining pregnancy
  11. 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. 12. Placenta - Functions MOTHER NUTRITION OXYGEN ANTIBODIES HORMONES PLACENTA FOETUS CARBON DIOXIDE METABOLITES STORAGE PLACENTAL HORMONES BLOOD
  13. 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. 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. 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. 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. 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.
  18. 18. 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
  19. 19. PARTURITION  Parturition is a process by which the fetus, membranes and placenta are expelled from the uterus  It is also called labour
  20. 20. 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
  21. 21. 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.
  22. 22. 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.
  23. 23. 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.
  24. 24. PLACENTA – AFTER EXPULSION
  25. 25. 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”
  26. 26. 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.
  27. 27. Regulation of Parturition
  28. 28. LACTATION Definition  Process by which milk secretion is Initiated, maintained and ejected Secreted by mammary glands Natural food of newborns .
  29. 29. COMPOSITION  Colostrum  Fat – small globules  Carbohydrate – Lactose  Protein – Lactalbumin - Lactoglobulin - Lactoferrin, Lysozyme, Leukocytes - Long chain W-3 Fatty acid - IgA
  30. 30. STAGES OF LACTATION  Mammogenesis  Lactogenesis  Galactokinesis  Galactopoiesis
  31. 31. 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
  32. 32. 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.
  33. 33. 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
  34. 34.  SUCKLING REFLEX OR  MYOEPITHELIAL REFLX
  35. 35. 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
  36. 36. 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.
  37. 37. 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
  38. 38. STAGES OF LACTATION
  39. 39. Thank You

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