THE PLACENTA

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THE PLACENTA

• Anna Mae Smith, MPAS, PA-C

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PLACENTA

• Synthesize
• cholesterol
• glycogen
• fatty acids
• Especially early in the pregnancy

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Placenta

• FETAL SIDE
• MATERNAL SIDE
• They provide
• protection
• nutrition
• respiration
• excretion
• hormone production

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Placenta

• FETAL SIDE
• develops from the chorionic sac
• MATERNAL SIDE
• DECIDUA - formed from the
• endometrium

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PLACENTAL ATTACHMENT

• Posterior wall
• Anterior wall
• Fundus
• With consecutive pregnancies the blastocyst
  attaches lower in the uterus

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Placental Transfer

• Diffusion
• water
• electrolytes
• minerals
• gases
• O2 sat in mom 70
• O2 sat in umbi. Vein 65

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Placental Transfer

• Active Transport
• Sugars
• Amino Acids
• Fatty Acids
• Pinocytosis
• Gamma globulins - passive
• immunity
• Viruses may pass no bacteria!!

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Hormones that cross the placenta

• Thyroxine, T3
• Testosterone
• Synthetic progestins

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Antibodies

• Passive immunity IgGs
• Diptheria
• Smallpox
• Measles
• Not chickenpox or pertussis

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Infections

• CMV
• Rubella
• Coxsackie
• Varicella
• Polio
• Syphilis
• Spirochetes

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Congenital Cataracts in rubella
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Placental Transfer

• There is normally no blood mixing between fetus
  momhowever, small amounts may enter through very
  small gaps in the fetal membrane!
• No transfer of cholesterol, triglycerides or
  phospholipids

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DRUGS

• Most drugs metabolites cross the placenta by
  diffusion
• Fetal drug addiction

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Placental Production

• Progesterone - hormone of pregnancy!!
• Formed from maternal
  cholesterol or pregnenolone
• - Initially produced by the corpus
  luteum
• Estrogen - estriol

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Amniotic Fluid

• 1st Trimester - by diffusion
• Later by fetal kidneys lungs
• Circulation -
• 1.swallowed absorbed into the
• fetal blood stream
• 2.Diffuses across placental mb back into
  the space
• 3.Excreted by kidneys lungs

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FETAL CIRCULATION

• Umb. Vein carries O2 blood from placenta to the
  fetus LIVER
• DUCTUS VENOSUS - shunts the blood to the inferior
  vena cava
• Right atrial opening into the Left atrium
• Ovale foramen

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FETAL CIRCULATION

• DUCTUS ARTERIOSUS - Opening to the descending
  aorta
• Responsible for blood return back to the
  placenta through the umbilical arteries

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After Birth

• STOP blood flow through umbilical vessels
• therefore immediately decrease pressure in
  right atrium
• The foramen ovale is sealed off by the septum
  primum

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FIRST BREATH

• Open up the pulmonary vasculature, allowing more
  blood to flow to the lungs
• Arterial pressure to the ductus arteriosus
  decreases
• Descending aorta branches take over output from
  the left ventricle
• Oxygenated blood leaks into the DA causing
  contraction of these cells which attracks fibrin
  to close this primum septum

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AS Adults...

• Umbilical Vein - Ligamentum teres( free edge of
  the falciform ligament)
• Ductus Venosus - Ligamentum Venosum Stretches
  from the left branch of the portal vein to the
  inf. Vena cava vein
• Ductus Arteriosus - Ligamentum arteriosum stems
  from the left pulmonary art. To the under surface
  of the aortic arch