Module 9: 2nd and 3rd trimester normal anatomy: placenta and cord Flashcards
What is the placenta classified as an organ that does that? 5
- Provides nutrients to the fetus
- Transfer of oxygen
- Removal of fetal waste
- Temperature regulation
- Excretion of hormones (hCG)
What is some of the waste removed by the placenta? 3
- Urea
- Uric acid
- Bilirubin
By 12 weeks gestation how many distinct components of the placenta is recognizable? 2
Two
1. Fetal portion: chorion frondosum
2. Maternal portion: decidua basalis
The fetal and maternal portion of the placenta are held together how?
By anchoring of stem villi at the cytotrophoblast shell
From top to bottom what does the red arrows point to?
- Chorion frondosum
- Decidua basilis
What does the syncytiotrophoblast do?
Create the large intervillous space in the decidua basalis (lacune)
The remaining portions of the decidua basalis are called what?
Placental septa.
The placental septa are divided into what?
Compartments called Cotyledon
What is the functional unit of the placenta?
Cotyledon
Each cotyledon consists of what?
Several stem villi
There are how many cotyledons in a placenta?
about 20
What does the red arrow point to?
Placenta septa
What is the maternal circulation like?
Spiral arterioles shoot blood around the chorionic villi
What is fetal circulation like?
From umbilical arteries to chorionic villi back to umbilical veins to baby
What does this image show?
Left goes towards baby and the right goes towards mom
What is the functions of the placenta? 6
- Respiration
- Nutrition
- Excretion
- Protection
- Storage
- Hormonal production
What is the respiration function of the placenta? 3
- Oxygen in the maternal blood diffuses across the placental membrane into the fetal blood by simple diffusion
- CO2 dioxide also passes readily in the opposite direction
- The placenta, therefore acts as a the lungs of the fetus
What kind of nutrients from the material blood makes it through the membrane into the fetus? 6
Nutrients from maternal blood through the placental membrane into the fetal blood such as,
1. Water
2. inorganic salts
3. Carbs
4. Fats
5. Proteins
6. Vitamins
How does excretion functions of the placenta work? Where is waste excreted?
- waste products cross the placental membrane from the fetal blood and enter the maternal blood
- They are excreted by the mother’s kidneys
How does the placenta protect the baby? Is there blood mixture between mom and baby?
- Most microorganisms do not cross the placental membrane
- There is no appreciable mixture of maternal and fetal blood
The placental membrane is sometimes referred to as what, however they don’t protect against what? 2
Placental barrier but it does not protect the fetus from many damaging agents such as
1. Drugs, poisons, carbon monoxides
2. Certain viruses (Rebella)
Once in a fetus, substances can cause what? What are these known as?
Congenital malformations, these are known as teratogens
What is the storage function of the placenta? What is stored? 5
Nutrients are stored in the placenta and area released into fetal circulation as required. Some things stored are:
1. Carbs
2. Proteins
3. Calcium
4. Iron
Where are hormones produced in the placenta? What is produced? 5
Production of the following hormones by the syncytiotrophoblasts
1. HCG
2. Estrogen
3. Progesterone
4. Human chorionic somatomammotropin (HPL human placental lactogen)
What is the sonographic appearance of the placenta around 10-12 weeks? What is present along the basal plate and in the septa?
- Diffuse granular echo pattern, apparent as early as 10-12 weeks (texture is produced by the echoes from the villi)
- Draining veins are present along the entire basal plate and in the septa
In terms of the sonographic appearance, the basic texture does not change with gestational age except for what?
The deposition of calcium
Placental calcifications are present in what amount? And when?
> 50% of placentas after 33 weeks
Calcium deposits are found primarily where? Where might they be found?
- The basal plate and septa
- May be seen in the subchorionic and perivillous space
Amount of calcification is increased in patients with what? 3
- IUGR
- Hypertension
- Smoking
What does this image demonstrate?
The early sonographic appearance of the placenta
What does this image demonstrate?
Normal placenta
What does these images demonstrate?
Maternal Lakes