1.) Placenta , Umbilical Cord , Amniotic Sac Flashcards
Placenta ?
Temp organ that serves as an interface between the mum and fetus facilitating essential functions such as nutrient uptake , eliminating waste , gas exchange , hormone production
Structure of placenta ?
22cm diameter , 2cm thickness , 0.7kg weight , disc shaped
The placenta can be in which other shapes ?
Disc , circular , oval , heart shaped
When does placental dev begin ?
2nd week and full functionality around 12th week
The placenta originates from ?
The blastocyst , with the fetal component derived from the chorion frondosum and maternal part decidua basalis
What is the decidua ?
modified endometrial lining of the uterus during pregnancy
Types of decidua ?
1.) Basalis underlines the implantation site , part of placenta.
2.) Capsularis covers the embryo
3.) Parietalis lines the rest of the uterine cavity
during implantation the blastocyst sinks into the uterine wall which decidual layer does it sink into ?
Decidua basalis
What are the functions of the placenta ?
Nutrients and gas exchange : transfer 02 and nutrients to fetus while removing co2
Immune protection : Transfers maternal IgG antibodies to fetus providing passive immunity.
Hormone production : HCG , Estrogen , progesterone , human placental lactogen (helps fetal growth , reg maternal metabolism )
maternal circulation ?
maternal spiral arteries supply blood to the intervillous space where exchange occurs with placental villi , blood returns to the uterus via endometrial veins
What is hcg ?
It helps thicken a person’s uterine lining to support a growing embryo and tells the body to stop menstruation
How does hcg tell the body to stop the menstrual cycle ?
hCG (human chorionic gonadotropin) maintains the corpus luteum, which continues to produce progesterone.
Progesterone prevents the uterine lining from shedding, thereby stopping the menstrual cycle during pregnancy.
What is the corpus luteum ?
Its a temporary mass of cells that form on the ovary each menstrual cycle it appears in one of the ovaries contains follicular granulosa cells and follicular theca cells
When does implantation occur ?
Implantation occurs about eight to nine days after fertilization
What are the steps to forming a blastocyst ?
Fertilisation , day 1 zygote , then day 3 morula (16-32) cells , then day 4 blastocyst 100 cells
Post-delivery, the umbilical vein degenerates into the ?
ligamentum venosum , and the arteries form part of the umbilical ligaments
What is the structure of the maternal side of the placenta?
The maternal side is lobulated, containing cotyledons, which are subdivisions made up of chorionic villi anchored to the uterine wall.
How does amniotic fluid contribute to fetal lung development?
The fluid allows the fetus to practice breathing movements, which helps develop and expand the lungs.
What is the umbilical cord ?
its the lifeline bet the fetus and placenta.
when does the umbilical cord form ?
5th week replacing yolk sac as the primary source of nutrients
length and diameter of umbilical cord ?
20 inches length and 0.75 inches in diameter
how many arteries/veins in umbilical cord?
2 umbilical arteries carry deoxygenated blood from fetus to placenta
1 umbilical vein returns oxygenated blood to fetus surrounded by Whartons jelly which protects the vessels from compression
Name 3 umbilical cord pathologies ?
1.) Umbilical cord compression can reduce 02 supply.
2.) Umbilical cord prolapse , the cord descends before the fetus during delivery
3.) Vasa previa , fetal blood vessels cross near the cervical opening.
Amniotic sac ?
thin protective membrane that encloses the dev fetus and amniotic fluid
Name the 2 layers of the amniotic sac ?
1.) Amnion , inner layer enclosing fluid.
2.) Chorion , outer layer which is part of the placenta.
Amniotic fluid function ?
Cushions and protects fetus , allowing free movement , prevents compression
amniotic fluid is composed of ?
Initially maternal plasma , it is then replaced by fetal urine y 20 weeks
What are the vol changes of amniotic fluid from 10-20 weeks and 28th week and 42 week ?
10-20 weeks increases from 25ml to 400ml and by 28th week it peaks a 800ml , reduces to 400ml by 42 weeks
Name 3 pathologies related to amniotic fluid ?
- Meconium stained fluid , indicates fetal distress risk of aspiration syndrome
-Oligohydramnios low fluid <500ml associated with growth restriction.
-Polyhydrmanios , excess fluid >2000ml linked to gestational diabetes or multiple pregnancies
