The Placenta Flashcards
What invades the uterine wall?
Syncitiotrophoblast
When does the blastocyst enter the uterine cavity?
Day 4/5
When is the blastocyst fully embedded within the endometrium?
Day 10
“Implantation is interstitial” explain this.
Uterine epithelium is breached and conceptus implants within stroma
Why does placental membrane become progressively thinner?
Fetal needs have increased
What happens to placental membrane as fetal needs increase?
Become progressively thinner
Define haemomonochorial
One layer of trophoblast separates maternal blood from fetal capillary wall
What are the two portions of the placenta?
- Fetal portion
- Maternal portion
What is the fetal portion of the placenta made up of?
- Chorion frondsum
- Chorionic plate
What is the maternal portion of the placenta made up of?
- Decidua basilis
- Decidual plate
What is most intimately incorporated into the placenta?
Decidual plate
What can be found between the chorionic and decidual plates?
Intervillus spaces
What fills the intervillus spaces?
Maternal blood
What projects into the intervillus spaces?
Decidual septae
When are decidual septae formed?
During months 4/5
What is the purpose of the decidual septae?
To divide the placenta into compartments called cotyledons
What are three features of the first trimester placenta?
- The placenta is established
- Placental barrier to diffusion is relatively thick
- Complete cytotrophoblast layer between syncitiotrophoblast
What are three features of the term placenta?
- Increased surface area for gas exchange
- Placental barrier to diffusion is now thin
- Cytotrophoblast layer is lost
Which fetal blood vessels are present in the placenta?
- Two umbilical arteries
- One umbilical vein
What is the function of the umbilical arteries?
Carries deoxygenated blood from fetus to placenta
What is the function of the umbilical vein?
Carries oxygenated blood from placenta to fetus
What is passive diffusion influenced by?
- Concentration gradient
- Barrier to diffusion
- Diffusion distance
Which substances are actively transported?
- Amino acids
- Iron
- Vitamins
Which substances move via facilitated diffusion?
Glucose
Which substances move via simple diffusion?
- Water
- Electrolytes
- Gases
- Urea
- Urease
List five teratogens that may cross the placenta.
- Thalidomide
- Alcohol
- Therapeutic drugs
- Drugs of abuse
- Maternal smoking
List five pathogens that can cross the placenta,
- Varicella zoster (VZV)
- Cytomegalovirus (CMV)
- Treponema pallidum
- Taxoplasma gondii
- Rubella
What four protein hormones are secreted by the placenta?
- Human chorionic gonadotropin (hCG)
- Human placental lactogen
- Human chorionic thyrotropin
- Human chorionic corticotropin
What two steroid hormones are secreted by the placenta?
- Progesterone
- Oestrogen
Aside from hormones, what else does the placenta synthesise?
- Cholesterol
- Fatty acids
- Glycogen
When does maternal IgG begin to be transported to fetus?
Week 14
How is maternal IgG transported to the fetus?
Receptor mediated pinocytosis
What divides intervillus space into cotyledons?
Decidual septae
