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PHY V > Pregnancy > Flashcards

Pregnancy Flashcards

1
Q

Fertilization steps

A

Step 1: Sperm arrives and penetrates expanded cumulus oophorus. Digestion of ECM

Step 2: ACROSOMAL REACTION = Sperm penetrates zona pellucida.
>Binds to ZP3 -> release of enzymes that digest the area (acrosomal reaction) -> bind to ZP2

Step 3: Sperm fuses with egg membrane

Step 4: As it fuses, starts the Ca2+ signaling cascade through IP3-DAG mechanism

Step 5: Activation of cortical granules to release it enzymes outside. These enzymes react with ZP2 and ZP3 such that:
-ZP2 can no longer bind acrosome-reacted sperm
-ZP3 can no longer bind capacitated-acrosome-intact sperm
THUS, only one sperm enters the egg.

Step 6: The entire sperm enters the egg during fusion. The flagellum and mitochondria disintegrate. Once inside the egg, there will be decondensation of the sperm DNA because of this decondensation, there will be the occurrence of a pronucleus.

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2
Q

Genetic events following fertilization

A

Egg will complete its 2nd meiotic division -> Both egg and sperm from a pronuclei -> They start to replicate as the pronuclei are pulled together and once in contact, they will have an alignment and the 1st cleave will occur followed by subsequent division.

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3
Q

How many mL per ejaculate? Sperm?

A

2-5 mL per ejaculate = 20 - 200 million sperm

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4
Q

Effect of capacitation

>Action and direction of the sperm

A

> Sperm becomes hypermotile.

> Sperm is able to locate/proper themselves towards that egg and the barriers.

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5
Q

How does the developing conceptus signal its presence to the mother?

A

Through hCG (Human Chorionic Gonadotrophin)

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6
Q

What implants to the uterus?

A

Blastocyst

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7
Q

Implantation

  1. Where does this happen?
  2. For how long does this happen?
  3. Processes
  4. What signal promotes attachment and implantation?
A
  1. Fallopian Tube
  2. 3 days
  3. Apposition -> Adhesion -> Penetration/Invasion
  4. Rise in hCG (initially: first 9-12 weeks) and then progesterone (after 12 weeks)
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8
Q

Source of nutrients for the developing fetus

A

Initially, corpus luteum but eventually it will be the placenta.

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9
Q

Beginning of implantation, the trophoblast may differentiate into 2 parts

A

> Syncytiotrophoblast

>Cytotrophoblast

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10
Q

Different steps of implantation

A
  1. Hatching
    >Before initiation of implantation (which is a week after ovulation), the zona pellucida that surrounds the blastocyst degenerates
    >Factors promoting the dissolution of the ZP: alternate uterine contractions, lytic factors of the uterine secretion, maternal progesterone levels in the luteal phase
  2. Apposition
    >Technically, the first contact between the blastocyst wall and the endometrial epithelium.
    >Usually at the site where ZP was ruptured
    >Mechanism for apposition: Lose zone pellucida proteins and changes in GPs and their terminal sugars that will decrease the electrostatic repulsive forces so they will now come into contact with each other
  3. Adhesion
    >Trophoblast appears to attach to the uterine epithelium via the microvilli of the trophoblast
  4. Invasion
    >Sometimes produces some degree of bleeding (so mens for 1 day =/= not pregnant)
    >Blastocyst attaches to the endometrial epithelium/lining, the trophoblastic cells rapidly proliferate then dx into: syncytiotrophoblast and cytotrophoblast
    >During implantation, long protrusions from the syncytiotrophoblast extend among the uterine epithelial cells and they dissociate the endometrial cells by TNF-alpha. Interferes w/ the expression of cadherins and beta catenin allowing the syncytiotrophoblast to get through the cells.
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11
Q

What is the yolk sac?
>When does it show? Fate?
>Function

A

> Structure that persists for the first few weeks of pregnancy
Usually part of ICM and provides the needs of the baby in terms of blood because it is the main site of erythropoiesis within these first few weeks of pregnancy
Eventually, it will get reabsorbed, degenerate, and disappear
In the 2nd trimester, it’s no longer producing cells, liver will take over and eventually the BM

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12
Q

Maternal response to implantation

A

Endometrial lining + stromal/supporting cells transform into your “decidua” (maternal side)

Decidua
>Becomes epithelial-like shape with adhesive junctions that inhibit migration of the implanting embryo!!! (Must know!!!)
>secretes tissue inhibitors of metalloproteinases that moderate the activity of syncytiotrophoblast-derived hydrolytic enzymes in the endometrial matrix
>allows regulated invasion

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13
Q

What happens if decidualization does not happen?

A

Placenta Accreta Spectrum
>Attaches too deeply into the uterine wall into the uterine muscles and all levels; may also invade nearby organs
>Problem: Need to remove uterus otherwise will cause excessive blleding. Once the placenta attaches to the myometrium, it will not allow the myometrial area to contract after delivery whose fxn is to prevent bleeding.

Placenta Accreta - placenta attaches too deeply into the uterine wall
Placenta Increta - attaches into the uterine muscle
Placenta Percreta - invades nearby organs like the bladder

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14
Q

Decidual zones during early embryonic development?

A

Decidua basalis - area underneath the implanting embryo

Decidua capsularis - encapsulates/overlies the embryo

Decida parietalis - covers remaining of the uterine surface

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15
Q

T or F. There is a direct link between the fetal and maternal vessels. If T, what?

A

F!!! No direct attachment. They only communicate through the villus spaces.

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16
Q

What happens during:

  1. 8 days after fertilization?
  2. 12-15 days later?
  3. 20 days after
A

8 days after fertilization
>Blastocyst has implanted
>Syncytiotrophoblast invade the stroma of the uterus
>Decidua development w/in these are you lacunae

12-15 days later
>Invading syncytiotrophoblast breaks through into the endometrial veins then the arteries later
>Cytotrophoblasts proliferate proceeding to the formation of your primary chorionic villi

20 days
>Primary chorionic villus will continue to grow into your secondary chorionic villus (Mesenchyme from extraembryonic coelom invades the villus)
>W/ formation of fetal capillaries -> becomes tertiary chorionic villus until it becomes your mature chorionic villi
>Lacunar spaces as it invades the vessels in the endometrial side start to merge and create one big space called intervillous space

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17
Q

Orientation of the arteries and veins to the uterine wall? Importance?

A

Spiral arteries are perpendicular while veins are parallel.

Importance: Uterus contracts and when it does, it can impinge vessels but because of this anatomical feature of the vascular layer, it will prevent from compressing the arterial side because it is important that you promote placental perfusion at all times.

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18
Q

Principal factors regulating the flow of maternal blood in the intervillous space?

A

Pattern of uterine contraction

Intrauterine pressure

Arterial BP

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19
Q

What does the cytotrophoblast have to undergo in order for the blood to go and proceed to the placenta feeding the fetus? What if there is a disturbance in this process

A

Modified cytotrophoblast cells will destroy the muscular wall and modify the vascular lining of the cell from being highly resistant to low resistance vessels. Thus, the placenta is a very low resistance vascular bed.

Disturbance in this process will lead to PREECLAMPSIA
>Mom has high BP and many more things
>May be due to problems with successful invasion

20
Q

Effect of hypertension on the size of the baby?

A

HPN -> vessels are constricted -> placental flow is constricted -> placental dysfunction leading to diminished supply -> small baby or growth retarded because the nutrients are lacking

21
Q

Fetal blood flow

>Managed by? Which is made up of?

A

Umbilical cord which is made up of 2 arteries and 1 vein

22
Q

Amniotic fluid

  1. Function
  2. Why don’t we drown in this fluid given that it surrounds us?
  3. You rotate to OB. What should you check in the amniotic fluid?
A

1.
>A mechanism by which the fetus excretes many waste products.
>Serves as a mechanical buffer from physical insult

  1. We swallow it, urinate, and add to it, as well.
  2. Quality and quantity.
    If the quantity is high (more than 2L) = polyhydramnios
    -> Urinates a lot so probably mommy is either diabetic or has GI obstruction

If qty is very low = oligohydramnios
>Possible problem: Renal agenesis (doesn’t urinate)

23
Q

What separates the maternal and fetal blood supply, ensuring that there’s no intermixing happening? Other functions?

A

Placenta!

>Substances can also transfer within this area either by active transport of passive diffusion influenced by blood flow

24
Q

Effective placental development is critical. Why?

A

If you have placental dysfunction, the fetus inside can develop malnutrition leading to intrauterine growth retardation.

If there’s loss of regulation such as in mothers with gestational diabetes -> infants can get microsomia

25
Q

How do we protect the fetal allograft from attack by the maternal immune system?

A

The syncytiotrophoblast forms a physical shield and they can express certain inhibitors of the complement cascade.

26
Q

Human Chorionic Gonadotropin

  1. What elaborates it?
  2. When does it peak?
  3. Does it always mean pregnancy?
  4. Functions
A

> 1st key hormone
These are elaborated by your corpus luteum then eventually by placenta
Peaks w/in the 1st trimester
Doesn’t always mean pregnancy because there are some tumors producing HCG
Functions:
1. Maintains the function of the corpus luteum
2. Stimulates your Estrogen and Progesterone
3.Inhibits contraction produced by oxytocin (uterine quiescence) allowing fetal growth

27
Q

Progesterone
>What secretes it?
>Function

A

> Placenta
Facilitates capacitation, sustenance of fetus, inhibits maternal immune response to Ags, quiescent hormone for the uterus

28
Q

Estrogen

>Effects

A

> Has effects on the breast ductal system
Relaxes and softens the maternal pelvic ligament so needed just before parturition/delivery BUT elevated all throughout

29
Q

Human chorionic somatomammotropin/Human placental lactogen
>Synthesized by?
>Function?

A

> Synthesized by syncytiotrophoblasts

> Functions:

  • Anabolic/Lactogenic function
  • Stimulates maternal lipolysis
30
Q

Prolactin

>Function

A

Functions:
>Milk production
>Depress the immune response of the fetus like progesterone

31
Q

Relaxin

  1. Produced by?
  2. Rise when?
  3. Role
A
  1. Produced by corpus luteum
  2. Rise early in pregnancy and peaks in 1st trimester
  3. Relaxes/softens the pelvic ligaments, cervix dilatation (to facilitate delivery)
32
Q

Maternal changes during pregnancy. What happens to:

  1. Total blood volume
  2. Total body water
  3. Red cell mass
  4. CO
A

Increase all 4. Still, you see physiologic anemia because the water content increases too so it becomes dilutional

33
Q

Effect on the BP when lying supine?

A

The IVC is compressed so position should be sideways to avoid compression.

34
Q

Resting position of the diaphragm during pregnancy?

A

Elevated

35
Q

Why do you see proteinuria or a bit of sugar in the urine of pregnant women sometimes?

A

The renal plasma flow increases that will inc GFR. The rise in BV will lead to an inc in CO. Thus, greater quantities of solute traversing glomerulus. With no changes in the capacity to reabsorb, you spill it out in the urine.

36
Q

What happens to the maternal glucose/amino acid concentration during pregnancy?

A

Reduced and diminished responsiveness to insulin as well = “diabetogenic” effects of pregnancy

37
Q

What happens to the energy used by the maternal and fetal compartments?

A

HPL and PRL have antiinsulin action on the mother which will permit the substrate to go the fetus & supply the nutrients -> Dec maternal glucose bc of the antiinsulin action -> glucose is transported to the baby

38
Q

Parturition

  1. When does this occur at the average?
  2. Stages?
A
  1. Average: 270 days after fertilization (or 284 days after LMP)
  2. Stages:
    0: Quiescence
    >You have hormones that will make it relax and insensitive to uterotonics (PGs and Oxytocin)

1: Transformation/Activation
2: Active Labor

3: Involution
>Involution of the uterus
>You also give birth to the placenta

39
Q

How do we determine if the offspring is sufficiently mature to be delivered?

A
  1. Mature lungs
    >Increasing fetal cortisol leads to lung maturation
    >Better production of surfactants
  2. Degree of maturity of other organs as well (Brain, heart, etc)
  3. Placental production of CRH (linked to onset of labor)
    - Means that lungs are mature and baby is ready to go out
40
Q

Onset of Labor

>Regulation?

A

> Regulated by CRH production

>Leads to an increase in hormones like estrogen and oxytocin

41
Q

Estrogen vs. OT

A

Estrogen increases the number of oxytocin receptors
Oxytocin is a uterotonic hormone. It increases uterine smooth ms contraction and stimulates the formation of your prostaglandin. It’s 1 hormone that acts w/ a positive feedback mechanism (Remember: Sa repro, and nagpopositive feedback: Estrogen to pag ovulate to LH). Sa OT, positive feedback rin kasi you contract -> prod more OT -> more prostaglandin -> contract more

42
Q

Three factors to consider during labor?

A

StreetDance Club

Stretching of the ms fiber

Distention of the uterus itself

Critical size

43
Q

What are Braxton-Hicks contractions?

A

Slow or low amplitude contractions which are “ineffective” because an effective uterine contraction should allow the dilatation of the cervix and thinning out.

This is called false labor.

44
Q

Effect of circadian rhythm on labor?

A

Peak sensitivity of the myometrium to oxytocin and PGs: Midnight to 5 am

45
Q

What promotes maternal attachment to the neonate?

A

Oxytocin and Prolactin

46
Q

Endocrinology of Pregnancy

  1. OT
  2. CRH
  3. GABA
A

Oxytocin
>Reduces anxiety

CRH
>Pair bond formation

GABA
>Primes maternal brain and its rapid adaptation to postpartum caregiving behavior

PHY V (12 decks)

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