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- 1. THE PLACENTA BY: G.LUNGU
- 5. Objectives By the endof the presentation, learner should be able to describe: • the placenta • functions of the placenta • Placenta at term • Umblicol cord • Membranes and amniotic fliud • Abnormalities of the placenta
- 6. Description • It isa temporary organ shared by the mother and fetus • It develops from the outer layer of the pre-implantation embryo • The pre-implantation embryo (blastocyst) is segregated into two lineages: the inner cell mass and outer cell mass and outer cell mass • The outer layer organises into trophoblasts, later becomes the placenta
- 7. Description ct … Trophoblastproliferates and separetes into: • Inner cytotrophoblastic layer (fetal side) • The synctiotrophoblastic layer – outer layer (placental side / maternal side)
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- 9. FUNCTIONS OF THEPLACENTA • RESPIRATORY FUNCTION – oxygen from the mother passes into the placenta into fetal blood by diffussion. • Similary, the fetus gives off carbon dioxide into maternal blood
- 10. Functions ct … •EXCRETORY FUNCTION – end products of fetal metabolism such as urea, bilirubin and carbon dioxide cross the placenta into maternal circulation where they are excreted • NUTRITION FUNCTION – mothers blood supplies the fetus with nutrients such as CHO, water, salts, fats, proteins and minerals
- 11. Functions ct … •PROTECTIVE FUNCTION – placental barrier protects the fetus from many harmful substances. It is limited to viruses, bacilli, syphyllis, hepatitis since these can cross the placental membrane
- 12. Functions ct… • HORMONALFUNCTION – oestrogen, progesterone, HCG and HPL are produced by the placenta. They are responsible for preparing maternal body for labour and lactation
- 13. Functions ct … •PASSIVE IMMUNITY – immunity to diptheria, measles is passed to fetus from maternal antibodies.
- 14. Placenta at term •It is a connective link between mother and fetus • It is disc shaped organ, dark red in colour on maternal side and silver colour on the fetal side • It is 20cm in diameter, 2.5cm thick at the centre • It weighs 1/6 of babys weight (about 500g
- 15. Placenta at termct … • It has 2 surfaces i.e. Maternal and fetal side • The chorionic membrane extends from its edges forming a chorionic sac • The chorionic sac is lined with amniotic membrane which is filled with amniotic fluid • All nourishment of the fetus is derived from the mother through the placenta
- 16. Umblicol cord • Theconnecting body or stalk which joins the placenta and the fetus • It is usually inserted on lateral sides of the placenta or into the centre of the surface of the placenta
- 17. Umblicol cord • Itis about 50 cm long and 1.5cm thick in diameter UMBLICOL CORD INSERTION • BATTLE DORE INSERTION OF THE CORD – The cord is inserted at the very edge of the placenta
- 18. PLACENTA VELAMENTOSA –When the cord is inserted into the membranes instead of the fetal surface of the placenta
- 19. BLOOD VESSELS OFTHE UMBLICOL CORD ONE UMBLICOL VEIN – It is a thin walled wide lumen vessel which carries 85% of oxygenated blood from the placenta to the fetus TWO UMBLICOL ARTERIES – Thick walled and narrowed lumen. It carries deoxygenated blood from the fetus to the placenta.
- 20. • The bloodvessels are surrounded by a jelly like substance known as whartons jelly which protects and supports them
- 21. Umblicol cord • Sometimesthe whartons jelly form lumps known as false knots. • After delivery, inspect for presence of all the 3 vessels. A missing artery / vessels is associated with a congenital abnormality
- 22. THE AMNION • Alsoknown as amniotic membrane • The sac becomes filled with fluid derived from maternal circulation • The fluid is called amniotic fluid or liquor
- 23. Amnion • The sacincreases in size until it completely sorrounds the embryo which freely floats in the fluid • It is tough, translucent and smooth • It ruptures at birth • Some times the baby can be born with it and can lead to suffocation
- 24. THE CHORION • Itis a thick opaque membrane • It is friable (easily breaks into small pieces) • It Seen hanging from the edges of the placenta
- 25. NOTE: after deliveryof the placenta and membranes, the 2 membranes can be separated up to the point of cord insertion • Amniotic membrane, chorionic membrane and fetal side of the placenta forms the fetal sac.
- 26. Amniotic fluid • Itis similar to that of extra cellular fluid • 98% is water, 2% solids made up of electrolytes, proteins, creatinine, urea and uric acid, glucose, fats and hormones • It is clear alkaline fluid
- 27. ABNORMALITIES OF THEPLACENTA • Placenta succenturiata • Placenta bi partita or tripartita • Placenta circumvallata • Placenta infarct • Placenta oedema • Meconeum stained placenta and cord • placenta acreta
- 28. Summary • It isa temporary organ shared by the mother and fetus • It is a connecting link between the mother and fetus • It consists of two sides (fetal and maternal), two membranes (amnion and chorion) and umblicol cord. • It protects and supports the fetus by performing various functions like: respiratory, excretory, nutritive and barrier
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