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GIGU Final > Phys of pregnancy and feus > Flashcards

Phys of pregnancy and feus Flashcards

1
Q

What are the main functions of the placenta?

A
  • Fetal gut supplying nutrients
  • Fetal lung exchanging o2 and CO2
  • Fetal kidney regulating fluid volume disposing wastes
  • Endocrine gland synthesizing steroids and proteins that affet maternal and fetal metabolism
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2
Q

How is the placenta organized to allow for exchange btw mother and fetal circulations?

A
  • Large surface area for exchange
  • Highly developed vascularity of fetal and maternal omponents
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3
Q

What is the functional unit of the fetal placenta?

A

Chorionic villi, which have a lot of branching to increase the surface area for exchange

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4
Q

What do spiral arteries do?

A

They’re from maternal side and empty into the intervillous space which gets drained by maternal veins

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5
Q

Describe the regulation of maternal blood flow.

A
  • Spiral arteries empties spurts of blood into the intervillous space
  • Filling of intervillous space dissipates the force and reduces the velocity of blood
  • Slowing blood flow allows enough time for excchange of nutrients
  • Blood drains tbough venous orifaces and enters placenral veins
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6
Q

Describe fetal blood flow.

A
  • Two umbilical arteries carrying deoxygenated blood.
    • penetrates chorionic plate to form the chorionic villi capillary network to obtain oxygen and nutrients and return it to the fetus via umbilical vein
    • Terminal dilations in capillar networks allow for slower exchange
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7
Q
A
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8
Q

What happens to partial pressure of oxygen in the blood when oxygen diffuses into the chorionic villi?

A

Po2 of the blood in the intervillous space will fall to 30-35 mmHg and it is lower in the umbilical vein of teh fetus

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9
Q

How does CO2 transfer occur?

A
  • Driven by concentration gradient
  • In umbilical arteries (near term) PCO2 is 48 mmHg and 43 mmHg in he intervillous space
  • Fetal blood has slightly lower affinity for CO2 than the maternal blood so maternal will pick it up easier
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10
Q

How are urea/creatine and lipid soluble hormones passesd from fetus to mother and btw mother placenta and fetus?

A

Passive exchage

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11
Q

How does glucose get to fetus?

A

Facilitated diffusion

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12
Q

What three moleculues need primary and secondary active transport to get to the fetus to support growth?

A
  • AA
  • Vitamins
  • Minerals
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13
Q

What are the endocrine functions of the placenta?

A
  • Maintains pregnant state of uterus
  • Stimulates lobuloalveolar growth and maternal breasts
  • adapts maternal metab to support fetus
  • Regulates fetal dev
  • Reg timing and progression of birth
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14
Q

Where is hCG produced and what is it releated to?

A

Produced by syncytiotrophoblats and related to LH

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15
Q

What is the primary function of hCG?

A

Bind LH receptors in the CL to prevent luteolysis and maintain high levels of luteal derived progesterone

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16
Q

What is thought to be responsible for nausea assoc. with morning sickness?

A

hCG

17
Q

When do hCG levels begin to drop off?

A

10 weeks

18
Q

If leydig cells are present in the fetus and hCG enters fetal circulation what happens?

A

It stimulates the leydig cells to produce testosteroe as it has similar structure to LH

19
Q

What is hCS? Where is it produced, when can it be detected, what does it do?

A
  • Structurally related to GH and prolactin produced by syncytiotrophoblasts
  • Detected in maternal serum at 3 weeks
  • Conversion of glucose to fatty acids and ketones
  • can have antagonistic action to maternal insulin contributing to diabetogenicity of pregnancy
  • lipolytic actions help mom shift to free fatty acid use for energy
  • Promotes dev of maternal mammary glands during pregnancy
20
Q

Why is progesterone required thoughout pregnancy?

A
  • Needed for implantation and early maintenance of pregnancy
  • Reduces uterine motlily
  • Inhibits uterine contractions
  • Inducees mammary gland growth and differentiation
21
Q

What does estrogen do? (5)

A
  • Induces endometrial growth progesterone recepor expression aned LH surge prior to ovulation
  • Increases uteroplacental blood flow
  • Increases LDL receptor expression in synctiotrophoblasts
  • Induces prostaglandins and oxytocin receptors for parturition
  • Increase growth and dev of mammary glands
22
Q

When does the luteal placental shift occur and what is it?

A

Week 8

  • shift from corpus luteum productionn of progesterone to the placental production of progesterone
23
Q

How does placenta get cholesterol?

A
  • From maternal circulation
  • Placenta lacks 17 a hydroxylase and 17,20 desmolase for estrone and estradiol production and 16a hydroxylase for estriol
  • Mother supplies cholesterol and fetal adrenal gland and liver supply the enzymes needed
  • Placenta cant create all hormones needed, requires coordinated effort from maternal and fetal to make hormones
24
Q

WWhat three shunts does the fetal circulatory system use?

A
  1. Ductus venosus
  2. Foramen ovale
  3. Ductus arteriosus

Bypasses liver and lungs as they arent functional until after birth

25
Q

What is foramen ovale?

A
  • Hole in the septum of the atria creating a right to left atrial shunt allowing blood to bypass the right ventricle as lungs aren’t fully functional
26
Q

What is ductus arteriosus?

A
  • Bypasses pulmonary artery to the aorta
  • Right to left shut, from right ventricle blood goes to pulmonary arteries where oly small amounts of blood go to the lung and rest is shunted to ductus arteriosus to descending aorta
27
Q

How does ductus arteriosus close?

A
  • As lungs expand there is a reduction in the pulmonary pressure and an inncrease in the aortic pressure this pressure change leads to closure of the duct
28
Q

What is a PDA?

A
  • Heart problem soon after birth due to ductus arteriosus not closing properly
    • can be heard as heart murmur
    • oxygenated blood from aorta will mix with deox in the pulmonary artery
    • puts strain on heart and increases pulmonary bp
29
Q

How does forame ovale close?

A
  • Reversal of the pressure gradiets across the atria pushes the forame ovale valves close
    • due to increase venous return to left atrium and elevated left atrial pressure and decreased right atrial pressure
  • Establishes the L and R circulatory system
30
Q

What is a PFO?

A
  • Foramen ovale failure to permanently close
  • Increased right atrial pressure can push the flap open
  • Sustained pulmonary htn or transient increases with sneezing coughing etc…
31
Q

How does ductus venosus close?

A
  • Within 1-3 hours the muscle wall of the ductus venosus will contract and close due to the decreased blood flow and pressure changes
  • Portal venous pressure will rise forcingn venous blood thorugh the liver sinuses
  • Permanent closrue within 1-3 months and this rarely fails to close
32
Q

What is ductus venosus?

A
  • Shunt that takes blood from placenta via umbilical vein and inferior vena cava to bypass liver into the right atrium of the heart

GIGU Final (12 decks)

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