Placenta (Exam 2) Flashcards
What does the fetal part of the placenta separate
fetus from endometrium
What are the fetal membranes
amnion
chorion
yolk sac
allantois
What are the functions of the placenta
nutrition protection excretion hormone production respiration
What is the function of the fetal suprarenal gland
produces hormonal precursors
What part of the fetus is the fetal suprarenal gland involved in
fetal-placenta circulation
How are the hormone precursors from the fetal suprarenal gland distrubuted
back and forth between the adrenal and placenta
What are the two parts of the placenta
fetal
maternal
Where does the fetal portion of the placenta arise from
chorion
Where does the maternal portion of the placenta arise from
endometrium
What is the decidua
maternal part of the placenta
What occurs to the decidua after birth
falls away from the rest of the uterus
What are the 3 parts of the decidua
decidua basalis
decidua parietalis
decidua capsularis
What is the decidua basalis
deep to the fetus (base of impantation
What is the decidua capsularis
overlying the fetus (covers the implantation site)
What is the decidua parietalis
everything else
What is the decidua reaction
the CT (decidua cells) enlarge in response to increased progesterone preventing the syncytiotrophoblast from extending too far into endometrium
What are the components of the fetal part of the placenta
primary chorionic villi
secondary villi
tertiary villi
How are primary chorionic villi formed
cytotrophoblast cells extend into syncytiotrophoblast
What does trophoblast layer give rise to
cytotrophoblast and syncytiotrophoblast
What does extraembryonic endoderm layer give rise to
somatic and splanchnic mesoderm
What is placental abruption
When the placenta detaches from the wall prematurely
What are the functions of the yolk sac
transfer nutrients
blood development
primordial gut
germ cells
What layers form the chorion
somatic extraembryonic mesoderm and trophoblast
What are the functions of the allantois
blood formation
vessels persist
bladder development
How are secondary villi formed
when mesenchyme invades primary chorionic villi
How are tertiary villi formed
when mesenchyme give rise to blood vessels and blood cells
What do terteiary villi vessels fuse to form
capillary beds that connect to embryonic heart
When will blood start flowing through the embryonic capillaries
week 3
What is twin transfusion syndrome
identical twins share a placenta but get uneven blood dispersion so one is smaller
How is a cytotrophoblastic shell formed
cytotrophoblast extends through the syncytiotrophoblast and proliferates forming a cytotrophoblastic shell
What are vestigial twins
conjoined twins
How will villi of the decidua capsularis change as the sac grows
will degenerate to produce a smooth region on the chorion
What is fetus in fetu
when a fetus (conjoined twin) grows compeltely inside the viable fetus
How is the villus chorion formed
villi on the decidua rapidly increase in number and branch to form the villus chorion
What is the villous chorion
fetal placenta
Is the decidua basalis related to fetus or maternal
maternal
By the 4th month what occurs
almost all of the placenta is replaced by fetal
How is the chorionic sac anchored
chorionic villi attach to decidua basalis via the cytotrophoblast
What are placental septa
projections of decidua basalis towards the chorionic plate
What is the chorionic plate
amniochorionic membrane and fetal vessels
What is the function of the placental septa
divide the fetal placenta into cotyledons
What are cotyledons
stem villi and its branches that are attached to decidua basalis
What is the intervillous space filled with
maternal blood
What is an intervillous space
lacunar networks that formed in the syncytiotrophoblast
What occurs in the intervillous space
maternal blood is discharged into the intervillous space and chorionic villi are bathed in maternal blood
What drains the intervillous space
endometrial veins
What is the amniochorionic membrane
amniotic sac enlarges faster than chorionic sac and they eventually fuse
What does the fusion of the amniochorionic and decidua capsularis and decidua parietalis do
obliterate the uterine lumen
How does exchange between fetal and maternal blood occur
normally no contact unless breakdown in placental membrane
What is the fetal circulation
umbillical arteries
chorionic arteries
capillary bed
umbilical vein
How does the blood in the intervillous space relate to the mother’s circulatory system
outside the circulatory system of her
What does the placental membrane contain in layers up until 20 weeks of development
syncytiotrophoblast
cytotrophoblast
CT: Wharton’s jelly
endothelium of vessels
How will the placental membrane change after 20 weeks of development
layers condense even further as thin as syncytiotrophoblast and endothelium
What is exchanged in placental transger
nutrients gases steroid hormones electrolytes maternal antibodies fetal waste products
What are the beneficial things that cross the placental membrane
fetal waste products water, glucose, amino acids, vitamins RBC serum proteins, AFP nutrients oxygen, electrolytes maternal antibodies (igG and igA)
What are the things that cross the placental membrane and are harmful to the fetus
CO drugs Taxoplasmosis Gandii other viruses (Parvovirus, Listeria, Varicella Zoster, HIV) Rubella Cytomegalovirus Herpes Simplex Virus 2 Syphillis
What may result from a long umbilical cord
prolapse or coil around fetus
How long is the umbilical cord
22 inches
What percentage of pregnancies have knots in the umbilical cord
1%
What is the umbilical cord composed of
2 umbilical arteries
1 umbilical vein
What is the use of umbilical vessel catheterization
administer of fluids or for arterial blood gas/pressure monitoring; can be cannulated up to 6 days after birth
Where is amniotic fluid derived from
fetus and maternal tissue
How does maternal tissue contribute to amniotic fluid
diffusion of fluid from the intervillous space
How does the fetus contribute towards amniotic fluid
urine
What are the functions of amniotic fluid
prevent amnion from adhering to fetus protection development of lungs movement body temperature regulation homeostasis fo fluid and electrolytes
What can be determined by the size of the chorionic sac
gestational age
What are other ways to move across the placenta
breaks in the membrane
lesions and then crawl
crawl across
What is placenta accreta
placental villi attach to myometrium
What is placenta percreta
placenta perforates through myometrium and fails to separate from the uterine wall
What is erythroblastosis
occurs when there is Rh incompatibility between mother and fetus–mom has to be exposed to fetal blood and mo m makes antibodies against the fetal antigen
antibodies can cross the placenta in future pregnancy and attack fetal RBC causing anemia and edema
What is polyhydraminos
too much amniotic fluid
What is oligohydraminos
too little amniotic fluid
What are the two different types of twins
dizygotic (fraternal)
monozygotic (identical)
How are dizygotic twins formed
two eggs and two sperm
What causes increased ovulation
increased FSH levels
How are monozygotic twins formed
one egg and one sperm split
What are commonly shared spaces and things for monozygotic twins
1 chorion
1 placenta
What do each monozygotic twin have separate
amniotic cavities