Test 4: lecture 5 fetal

Question 1

the placenta serves as ___ for the fetus

Answer 1

endocrine organ

respiratory organ

excretory organ

circulatory organ

source of energy (glucose transport)

Question 2

umbilical ___ carries blood to the fetus and the umbilical ___ carries blood away from the fetus

Answer 2

vein (oxygenated)

artery (deoxygenated)

Question 3

prior to compaction ___ is the main source of energy

Answer 3

pyruvate

lactate (lactate dehydorgenase) → pyruvate

or

pyruvate can be absorbed

Question 4

after compaction ___ is the primary energy source

Answer 4

glucose

Question 5

8 cell stage until birth use ___ for energy

Answer 5

• 50% directly from glucose
• 25% indirectly from glucose
• 25% from fatty acids and amino acids
• Fructose (ruminants)

Question 6

brown fat

Answer 6

helps with thermoregulation

produces heat → more mitochondria - uncouples ATPase from electron transport chain which produces heat

Question 7

meconium

Answer 7

first poop of fetus

Question 8

energy usage immediately after birth

Answer 8

glucose drops → can use some glycogen stores but liver not working yet so can’t make more glucose

Fat: ⅔ of energy is from fats. Epinephrine increases lipolysis and fatty acids

milk→ neonates can absorb glucose from the milk from the mother

Question 9

vitamin B in fetus

Answer 9

formation of RBC and nervous system

Question 10

importance of iron in pregnancy

Answer 10

iron for oxygen binding in RBC

don’t make iron need to ingest it → very good at recycling it

Question 11

fetal circulation

Answer 11

L and R ventricles flow is in series AND (partially) in parallel

oxygenated blood comes from mother in umbilical vein

dumps into hepatic/inferior vena cava (ductus venousus) → heart → skips lungs (ductus arteriosus and foramen ovale) → through body and back to mother (round ligament of the bladder) through umbilical artery

O2 exchange, glucose transport and excretion happen at the placenta

Question 12

is the pulmonary pressure greater or less than the system pressure in the fetus

Answer 12

greater

lungs are collapsed

Question 13

ductus arteriosus

Answer 13

becomes the ligamentum arteriosum

(pulmonary artery → aorta)

skip the lungs

Question 14

foramen ovale

Answer 14

hole from L to R side of heart (skips the lung)

Question 15

ductus venosus

Answer 15

becomes the ligamentum venosus

skips the liver

Question 16

umbilical vein

Answer 16

becomes the round ligament of the liver

carries oxygenated blood to the fetus

Question 17

umbilical artery

Answer 17

carries deoxygenated blood from the fetus to the placenta

becomes the round ligament of the bladder

Question 18

flow of blood in fetus

Answer 18

55% of blood will return to the placenta

less O2 transferred

Question 19

circulatory changes at birth

Answer 19

umbilical cord closes → no blood flow to the placenta → systemic resistance increases and pressure in the L side of the heart increase

lungs expand and pulmonary blood flow increases → pulmonary vascular resistance and pressure in the Right side of the heart decreases

Question 20

what happens with increase in O2 to the pulmonary arteries

Answer 20

will increase size → vasodilation

(this is opposite of what happens elsewhere in the body)

Question 21

what happens to the shunts in fetal circulation after birth

Answer 21

Foramen ovale closes
• Increased left atrial pressure closes valve
• May take weeks to permanently close

Ductus arteriosus closes
• Flow initially reverses (left to right shunt)
• Closure is driven by increased O2 and decreased PGE2 (placenta provided PGE2)

Ductus Venosus closes
• Smooth muscle contracts within hours of birth, however mechanism is still being elucidated

Question 22

shift to right for O2 dissociation curve

Answer 22

easier unloading of O2

decrease pH

increase temp

Question 23

shift to the left of O2 dissociation curve

Answer 23

easier loading of O2 (doesn’t want to let go)

Question 24

Bohr effect

Answer 24

shifts curve to the Right

low pH

will let go of O2

Question 25

haldane effect

Answer 25

partial pressure of O2 will effect the ability to carry O2

less O2 = will bind to CO2 more easily

Question 26

double bohr effect

Answer 26

exchange of O2 from the mother to the fetus across the placenta

Question 27

secretions in the lung

Answer 27

caused by the movement of Cl (which pulls water) into the lumen

(during early stages of pregnancy)

Question 28

what happens to respiratory fluid later in pregnancy

Answer 28

Cl is pulled from lumen into the plasma and brings water with it (absorbed)

(decreases secretions in the lung)

Question 29

what happens to lung tissue during parturition

Answer 29

walls thin

surfactant production begins

increased capillary growth

Question 30

what stimulates respiration in neonate

Answer 30

Chemoreceptors • Release from immersion • Tactile stimuli• Temperature
• Rubbing • Licking • Sound • Other

Evidence suggests that a placental inhibitory factor is removed at birth, and regular breathing ensues

Question 31

how is fluid removed from the lung

Answer 31

most of fluid is resorbed via lymph

pressure through birth canal will expel fluid

Question 32

why do you need such a large negative pressure for the 1st breathe

Answer 32

high surface tension of the alveolar fluid and inherent increased elastiticty

Question 33

what changes in renal at birth

Answer 33

Arterial blood pressure increases

• Renal blood flow increases (~10% of cardiac output) (fetus has 3-7%, adult has 20-25%)
• Renal vascular resistance decreases
• GFR increases

Question 34

why can’t neonate renal concentrate urine well?

Answer 34

poor ability to concentrate urine cause low ADH function and increased urea excretion

can easily dehydrate when sick (vomit and diarrhea)

Question 35

why is acid/base balance tricky in neonates

Answer 35

kidneys not fully developed therefore they are not producing enough bicarb

diarrhea means bicarb can’t be reabsorbed and can easily upset acid balance