Exam 6: Fetal and Avian Gas Exchange Flashcards Preview

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Flashcards in Exam 6: Fetal and Avian Gas Exchange Deck (12)
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1
Q

Where does gas exchange occur in the fetus?

A

Placenta

2
Q

When is surfactant produced?

A

At about 85% of term

3
Q

What is the surge in surfactant production just before birth a result of?

A

Maternal and fetal corticosteroid production

4
Q

Why is surfactant important?

A

Reduces surface tension at the air/liquid interface in the lung
It maintains alveolar diameter, so it does not collapse on itself
Surfactant gets spread around within the alveoli during the first breath

5
Q

Is systemic blood pressure lower or higher in the fetus than in the dam?

A

Lower

6
Q

What is the PO2 of blood reaching the fetal brain?

A

17 mmHg

7
Q

What changes occur during birth that alter the function of the respiratory system during passage through the pelvis?

A

Decrease/expels fluid from lungs

8
Q

What changes occur during birth that alter the function of the respiratory system during the first breath?

A
Eased PVR (decreased HPV)
Increased SVR (vasoconstriction and termination of placental circulation)
9
Q

What changes occur during birth that alter the function of the respiratory system during termination of placental circulation?

A
Arterial constriction (stretching and increased PO2)
Umbilical veins do not constrict (autotransfusion)
10
Q

What changes occur during birth that alter the function of the respiratory system during closure of ductus arteriosus?

A

Active vasoconstriction
Increased PO2
Decreased prostaglandins help to close ductus arteriosus

11
Q

What is unique about fetal hemoglobin?

A

It has a higher affinity for oxygen so that uptake is easy from the maternal hemoglobin to the fetal hemoglonim

12
Q

What makes the avian respiratory system unique?

A

No diaphragm
Air sacs are connected to each other, the lung, and the pneumatic bone
Higher surface area/volume ratio
Thinner blood-air barrier
Gas exchange occurs in tertiary parabronchi
Birds have a lower function residual capacity
Avian hemoglobin is left shifted

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