Session 8 - Pregnancy Flashcards
Onw what day does the blastocyst implant into the endometrium?
6
What are primary, secondary, and tertiary placental villi?
Primary villi – early finger like projections into trophoblast
Secondary villi – invasion of mesenchyme into core
Tertiary villi – invasion of mesenchyme core by fetal vessels
What are the 3 pruposes of establishing a placenta
- Anchor the placenta – via establishment of the outermost cytotrophoblast shell
- Establish maternal blood flow within placenta
- Establish basic unit of exchange ie villi
What is an ectopic pregnancy? What are the consequences?
- Implantation at site other than uterine body, commonly fallopian tube
- Can be peritoneal or ovarian
- Can rupture and cause severe haemorrhage
What is placenta praevia? What are the consequences and how do you treat?
- Placenta grows below os of uterus
- Can cause haemorrhage in pregnancy
- Requires C-section delivery
What is placental insufficiency?
insufficient blood flow to placenta during pregnancy caused by incomplete invasion of placenta
What is pre-eclampsia?
hypertension and large amount of protein in urine during pregnancy caused by incomplete invasion of placenta
How is the endometrium prepared for implantaiton?
Decidualisation – provides the balancing force for the invasive force of the trophoblast:
- Stimulated by progesterone
- W/o this complications such as haemorrhage can occur
Remodelling of spiral arteries:
- Creates low resistance vascular bed
- This maintains a high flow rate required to meet fetal demand.
What is the fetal portion and the maternal portion of the placenta made of?
Fetal - Formed by chorion frondsum
Maternal - Formed by decidua basalis
What is found between the chorionic and decidual plates of the placenta?
intervillous spaces which are filled with maternal blood
What are cotyledons of the placenta?
Decidual septa formed in the decidual plate divide the placenta into compartments or cotyledons
How does the thickness of the placenta change in the first and second trimester?
First trimester placenta:
- Placenta established
- Placental barrer to diffusion still thick
- Complete cytotrophoblast layer beneath syncytotrophoblast
Second trimester placenta:
- Loss of cytotrophoblast layer
- Barrier thin
- SA for exchange increased
Where do cotyledons recieve their blood from?
through spiral arteries that pierce the decidual plate.
Which substances are actively transported across the placenta? What about facilitated diffusion?
Active transport:
- Amino acids
- Iron
- Vitamins
Facilitated diffusion:
- Glucose
Give 3 examples of teratogens
thalidomide, alcohol, smoking