PRACTICE QUESTIONS

1. The vascular channel that allows fetal blood to pass from the pulmonary artery to the aorta is known as the:

a. Foramen ovale

b. Ductus arteriosus

c. Ductus venosus

d.

e. Allantois

2. Which of the following is the correct sequence of events that follow birth?

a. Closure of foramen ovale, first breath, rupture of umbilical vessels

b. Decrease in right atrial pressure, first breath, closure of the ductus arteriosus

c. First breath, closure of the ductus arteriosus, decrease in pulmonary arterial pressure

d. First breath, decrease in pulmonary arterial pressure, closure of the foramen ovale

e. Closure of the foramen ovale, closure of the ductus arteriosus, first breath

3. Which of the following fetal blood structures contains blood with the highest Po₂ ?

a. Aorta

b. Ductus arteriosus

c. Pulmonary artery

d. Left ventricle

e. Umbilical artery

4. Which of the following statements about the fetal circula­tion is true⁷.

a. Right atrial pressure is higher than left atrial pressure.

b. Pulmonary vascular resistance is high.

c. The placenta receives about 45^o∕o of the combined output of both ventricles.

d. The output of the right ventricle is greater than that of the left ventricle.

e. All the above.

5. Which of the following does not correctly describe the lung in utero?

a. Type II cells, which produce surfactant, are present within the first few days of gestation in sheep.

b. Chloride-rich fluid is secreted into the airways and flows into the amniotic cavity.

c. Components of surfactant can be detected in the amniotic fluid when the lung approaches maturity.

d. All the major branches of the tracheobronchial tree are present at birth, but alveoli continue to multiply after birth in some species.

e. Breathing movements occur in utero, but the volume of fluid moved in and out of the lungs is small.

6. Fetal oxygen transport is assisted by:

a. Fetal hemoglobin, which has a lower oxygen capacity than adult hemoglobin

b. Fetal hemoglobin, which has a lower P₅₀ than adult hemoglobin

c. A cardiac output that is less per kilogram of body weight than in the adult

d. A cardiac output that preferentially delivers the blood with the highest Po₂ to the placenta

e. A fetal lung, which is an efficient gas exchanger

7. WTiich of the following domestic mammals has a diffuse, epitheliochorial placenta in which fetal and maternal blood flow is countercurrent in the microcotyledons?

a. Dog

b. Cow

c. Horse

d. Rabbit

e. Sheep