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BPK 307 > Pregnancy > Flashcards

Pregnancy Flashcards

1
Q

What happens during capacitation

A

Capacitation happens in female reproductive tract
- decapacitation factor is washed away by uterine fluid
- loss of high cholesterol environment (testes) weakens acrosomal cap (cholesterol hardens cap)
- sperm becomes permeable to Ca- activates whip like activity of flagella in tail

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2
Q

What does decapacitation factor due? Where is it produced

A

Epididymis
Suppress motility
Prevent capacitation reaction

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3
Q

Acrosome functions

A

Break granulosa cells- hyaluronidase = break down hyaluronic acid which is part of the connective tissue
Break zona pellucida- proteolytic enzymes

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4
Q

Function of Ca with sperm

A

Whip like motion of flagella in tail

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5
Q

What day of menstral cycle does fertilization occur

A

Day 16-17
Note ovulation 14

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6
Q

Steps of fertilization

A
  1. Hyaluronidase (in acrosome) breaks down granulosa cells and sperm bind to ZP3 glycoprotein (sperm has ZP3 receptor)
  2. Sperm-ZP3 interaction initiates the acrosomal reaction. Acrosomal reaction disrupts the acrosomal membrane, releasing proteolytic contents. Proteolytic enzymes bore into zona pellucida and digest it

3-4. Sperm penetrate ZP and fuse with oocyte membrane. Cytoplasmic portions of sperm enter oocyte. Accomplished by chemical- acrosomal enzymes and mechanical- sperm tail thrashing (Ca dependent)

5-6. Cortical reaction initiated by intracellular Ca release from intracellular stores of oocyte. Cortical reaction- exocytosis of granules that contain enzymes that harden ZP. Purpose to ensure only one sperm can penetrate the ovum. ovum complete second meiotic division to become haploid in preparation for fertilization

  1. Sperm nucleus decondenses and tail degenerates
  2. Male and female haploid pro nuclei fuse- form diploid zygote. Fertilization complete
  3. Fertilized ovum transported to uterus (3 days) during which cell divisions occur. End result blastocyst in uterus (100 cells). Uterine tube secretions provide nourishment
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7
Q

Importance acrosomal reaction

A

Disrupt acrosomal mebrane- breaking down
Proteolytic enzymes released- bore into ZP and digest it

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8
Q

Importantance cortical reaction

A

Harden ZP so no other sperm can penetrate ovum

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9
Q

Zygote development stages while travelling to uterus

A

Zygote- 1 cell- ampulla of uterine tube
Morulla- 16 cells- uterine tube
Blastocyst- 100 cells- uterus

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10
Q

How long between fertilization and implantation

A

3-4 days
Implantation day 20 menstrual cycle

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11
Q

Blastocyst properties

A

Has LH receptors
Secrete HCG- save corpus luteum
Secrete immunosuppressant
Blastocyst will become embryo

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12
Q

Why is implantation delayed after fertilization

A

Important for cell division and endometrium

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13
Q

What is decidualization ? what hormone maintains it?

A

Occurs before implantation
Changes to endometrium inner layers- decidua basalis (implant zone), decidua capsularis (surround embryo), decidua parietalis (surround rest of uterine surface)

  • progesterone from CL maintains decidualised endometrium
  • uterine milk- secretions from uterus that nourish blastocyst and embryo stages
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14
Q

What is uterine milk

A

glandular secretions- proteins, iron, fat soluble vitamins, cholesterol, nutrients
Nourish blastocyst and embryo stages

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15
Q

4 events of implantation

A
  1. Hatching and alignment of trophoblast- lytic factors break down zona pellucida (hardened state to degeneration). Trophoblast replaces outer layer (trophoblast will become placenta)
  2. Apposition- ruptured ZP causes blastocyst wall to lose contact with endometrial wall. Inner cell mass of blastocyst aligned with epithelium (of endometrium- same cells talked about throughout)
  3. Adhesion- ligand receptor interactions (integrin family- transmembrane proteins). Trophoblast (outer layer) attaches to uterus endometrial epithelium
  4. Invasion- syncytiotrophoblast invades endometrium. Trophoblast divides in two- syncytiotrophoblast + cytotrophoblast (outer layers still)
    - blastocyst eventually fully embeds in decidua and reaches maternal blood supply
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16
Q

What is in contact with maternal blood supply

A

Lacuna- fluid filled pools- exchange site
Exchanges excretions for maternal blood

17
Q

Syncytiotrophoblast and cytotrophoblast role in placenta development

A

Syn- Lacuna pools and mother blood vessels. Maternal part of placenta
Cyto- fetus blood vessels that reach into lacuna. Fetal part of placenta

18
Q

What reaches into lacuna to pick up maternal blood

A

Cytotrophoblast- finger like projections reach in. Will become fetal blood vessels

19
Q

Mature placenta key parts

A

Intervillous space- used to be lacuna. Filled with maternal blood

Mature chorionic villus- whole area. Covered with syncytiotrophoblast

Fetal Arterioles/venules- from cytotrophoblast

Umbilical vein- to fetus, oxygenated blood, nutrients
Umbilical artery- from fetus

20
Q

When does fetus heart start to beat

A

4 weeks

21
Q

Roles of placenta

A
  • site of exchange between mom and fetus
    Lungs
    GI tract
    Kidneys- waste removal and electrolyte balance
    Liver- waste removal
22
Q

What are the four circulatory shunts

A

Placenta- exchange site for maternal and fetal blood, nutrients

Ductus arteriosus- connect right pulmonary arteries to the aorta. Blood stays in systemic circulation. Flow to pulmonary vessels is low due to hypoxic vasoconstriction

Ductus venosus- connect umbilical vein to inferior vena cava

Foreman ovale- connect RA to LA. Allows ventricles to pump in parallel. Mixing of oxygenated and deoxygenated blood

23
Q

Discuss fetal oxygenation and the Bohr effect

A

Left shift of oxygen dissociation curve.
Fetal hemoglobin is more efficient at up taking O2 at lower pressures of oxygen compared to mom (less oxygen available but still can uptake)
Carry 25-50% more oxygen at low PO2
Hemoglobin concentration of fetal blood is 50% higher than mother
——
Placenta has low PCO2- fetal blood uptakes O2
In fetus high PCO2- fetal blood release O2 to its tissues
- all oxygen to fetus dependent on Hb- no lungs

24
Q

What are the roles of the 3 hormones of pregnancy

A
  1. Human Chorionic Gonadotropin- maintains the corpus luteum until the placenta takes over (12 weeks drop starts)
    - HCG produced by blastocyst
    - cause of morning sickness (severe= hyperemesis gravidarum)
    - tested for in pregnancy tests
  2. Estriol (E17B)- most important estrogen when pregnant- enlarge uterus, enlargement and ductal growth of breast tissue, relax pelvic ligaments
  3. Progesterone- decidualisation, lobular breast development, quiescent uterus- no contractions
25
Q

When is the switch from corpus luteum to placenta

A

8-12 weeks of pregnancy

26
Q

Explain maternal placental fetal unit- what does DHEA-S stand for

A

Hint- two important pathways
One for estrogen and one for progesterone- both of which fetus cannot be exposed to
Pg 14 pregnancy

27
Q

Other hormonal support of pregnancy- other than P + E

A

Pituitary -ACTH, TSH and prolactin -near complete suppression of LH and FSH (via inhibition from estrogen and P)

Corticosteroids -glucocorticoids (mobilise a.a. from mother for fetal tissue synthesis) -

aldosterone – 50% more salt retention and expansion of blood volume (1.5-2L)

Erythropoetin -increased red blood cell production in bone marrow

Thyroid hormone -enlarges 50% and increases thyroxine secretion 50% (hCG) Parathyroid hormone -enlarge and reabsorb Ca2+ from maternal bones / teeth to support fetal needs

Relaxin -from corpus luteum and placenta -relaxes ligaments of pubic symphysis, softens cervix and inhibits uterine contractions

28
Q

factors relating to pregnancy lose

A
  • Increased maternal age
  • Weight: underweight and overweight
  • Smoking/alcohol/drugs
  • ≥2 prior pregnancy losses
  • Chronic conditions e.g. uncontrolled diabetes/thyroid disease
29
Q

When are most pregnancy’s lost- what % of los preg are from this time

A

First 12 weeks
80% of pregnancies

30
Q

What can cause pregnancy lose

A

Causes Chromosomal abnormalities (~50%) – inherited or random
Maternal factors: cervical competence; uterine fibroids; endocrine imbalance; infections
Lots are Unknown

31
Q

What could be a sign of pregnancy loss

A

Heavy or delayed period

32
Q

% pregnancy’s lost out of all pregnancy’s vs the known pregnancy (persona aware of pregnancy)

A

Pr egnancy loss occurs 30-50% of all pregnancies and ~10-20% of known pregnancies

BPK 307 (13 decks)

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