Conception and Fetal Development Flashcards
Fertilization occurs when and where?
It occurs when there is a union of the nuclei of the sperm and ovum.
Location is in the outer third or ampulla of the fallopian tubes.
How long is the ovum fertile for?
How long can sperm survive? Fertile time phrame?
24 hours
Sperm can survive for 48-72 hrs.
Sperm are only fertile tho for 24 hrs as well.
(Sperm information contradicts her previous notes from family planning????)
So when the egg is released from the ovary & taken up into the fallopian tube - how does it move, again?
Ciliary movement and current pushes it along
How does the sperm move in order to meet the ovum?
Sperm have a tail that helps them move.
How many sperm should penetrate an ovum?
Which is bigger - ovum or sperm?
One sperm per ovum typically
The ovum is much bigger.
How is it that only one sperm can enter the ovum?
Zonal reaction or ability of the membrane to block other sperm.
What is conception?
What do the chromosomes do?
Formation of the zygote
The chromosomes then pair up. XX or XY
What does the zygote form into officially? And where does this formation burrow?
What is this process called? How many days should this take?
The zygote will form into the blastocyst.
And then the blastocyst will burrow into the endometrium - which is the inner lining of the uterus.
Process is known as implantation. Takes between 6-10 days.
What is the best site for implantation?
What name change occurs of the endometrium after implantation?
The side or posterior wall. NOT the front.
The endometrium or inner lining will have its name changed to decidua.
What is the site of implantation of the decidua (new name for endometrium)? What is it?
Decidua capsularis
It is a bubble structure that covers the blastocyst
What is is the maternal side of the placenta?
Decidua basalis. It serves as the base for the placenta.
What is the Decidua vera?
Remaining uterine lining of the decidua/endometrium that really isn’t all that affected by pregnancy.
Why are twins becoming more common?
Due to delayed child bearing and artificial reproductive treatments
Two types of twins?
Dizygotic
Monozygotic
Dizygotic twins
How many ovum and sperm needed?
How many placentas, chorians, amnions?
Two of everything because they are totally separate.
Will dizygotic twins always be the same gender?
No, these twins can be separate genders bc they’re separate in general.
What increases chances of having Dizygotic twins?
These twins are pretty much separate fyi…
Older pregnancy
Familial genes - twins tend to run in families
Going off the pill & having multiple ovum released.
Obesity
Monozygotic twins
Will have how many ovum and sperm?
How many placentas?
Will these be identical twins? Gender?
Will have one single fertilized ovum (so one sperm).
One shared placenta.
Yes - they are identical. Same gender as well.
Risk of monozygotic or identical twins?
What type of treatment could increase this?
Can become conjoined or have Siamese twinning where they are fused.
ART or artificial
Which types of twins will do better?
The Dizygotic twins will do better since they have their own stuff.
Monozygotic babies share placenta and possibly their chorion. Baby A gets the nutrients and Baby B is second.
Will blood ever be shared/mixed between mom and baby?
No - two separate circulatory systems going on. Unless there’s trauma and a vessel ruptures.
What do babies do to amniotic fluid that surrounds them?
They recycle it by drinking and peeing in it.
Cotyledons of placenta
Beefy red sub-sections of placenta
Fetal side of placenta
Where cord comes off of and attaches to the fetus.
Shiny, gray color
How big is the placenta at 20 weeks
How big is it by term
Covers 1/2 of uterine surface
By term it is 6-9 inch diameter and about 1 Ib
What if a mom is Rh-?
There could be mixing of blood due to maternal antibodies if baby is positive (it’s a blood type)
While there shouldn’t really be any mixing of blood unless there is something rare or abnormal - can the mother’s circulation affect the baby in any way?
Yes. Maternal circulation can increase or decrease uterine blood flow. Same thing can happen with mother’s blood pressure.
Ex: hypertension can decrease the CO and thus uterus &. placenta aren’t perfused doesn’t get enough
Uterine souffle
Listening over to maternal blood vessels which is the pulse of the mother. Whoosh noise.
Funic souffle
To listen to HR over umbilical cord that equals FHR - but you don’t want to necessarily listen to this.
Do it over the baby’s back.
What does the placenta transport?
How does the placenta act as the lungs?
Nutrients
Waste
Antibodies the last month of pregnancy/mother’s gift/passive immunity
Takes care of gas exchange components like O2 and CO2
Major hormones from placenta
hCG - basis of pregnancy testing; found in blood & urine
hPL - metabolism & growth in pregnancy
Estrogen - growth hormone of breast, uterus, blood
Progesterone - keeps uterus quiet and calm
Dirty duncan presentation
When placenta presents maternal side up with the Cotyledons
Where should the cord be on the placenta
In the center - unless there is an abnormality
Umbilical cord contains how many arteries and veins
acronym?
2 arteriers
1 vein
AVA - arteries on side and vein in center
Umbilical artery
Umbilical vein
Takes deoxygenated blood to placenta
Takes oxygenated blood to to the fetus
so reverse of your circulation
Percent of umbilical cords that only have 1 artery and 1 vein?
1%
The baby will still be healthy - but want to take a closer look to make sure there aren’t any other issues.
Does it hurt the baby when you cut the cord?
No - there’s no pain receptors.
How long is the cord?
Why does the length matter?
Same length of baby so 20-22 inches
If the cord is too short then it can get too tight and seperate
Protein around the umbilical cord?
What does the high blood volume help with?
Wharton’s Jelly - gelatin substance and water. Cushions the vessels.
Will fall off after delivery
It can keep the cord from tangling up around baby neck or having a nuchal cord. Can kill the baby
Ultrasound and doppler blood flow study helps with what?
Complications of pregnancy. Can check for blood flow through the vessels
Amniotic sac or Bag of water layers (2)
Are they fused together?
Amnion or inner layer that develops from the blastocyst. It is thin,
Chorion or outer membrane of the sac. Develops from the trophoblast and is thick.
No, they are not fused together.
Amniotic fluid amount at 39 weeks?
Amount at 41 weeks?
Main point?
700-900 mL
500 mL
So - this is why we never want a pregnancy to go past 40 weeks bc the amniotic fluid decreases.
Polyhydraminos
Excessive amount of amniotic fluid greater than 2L
Why would a baby have too much amniotic fluid (polyhydraminos)?
Gi issue like esophageal problem where baby can’t swallow their own amniotic fluid and so the fluid never gets recycled. It just accumulates in the sac.
Other reason is there could be more than one fetus and so more fluid is needed.
Diabetes - glucose can transfer to baby and the baby enlarges but also pees out everything so the fluid accumultes
Oligohydramnios
Not enough amniotic fluid so like less than 300 mL
Fluid will be super concentrated
half of the normal amount too
Why would a baby have Oligohydraminos or not enough fluid in their amniotic sac?
Since the fluid is recycled -
baby may not be excreting fluids due to kidney issues
Maternal drug use can cause no kidney in child
Or Reduced blood volume so less fluid
Or post date PG so 41 weeks