QuestionSBA
QuestionChoice
The foramen ovale allows the shunting of oxygenated blood from the inferior vena cava and right atrium to the left atrium. Once a baby takes its first breaths and the pulmonary circulation opens, the decrease in pulmonary resistance causes the left atrial pressure to exceed the right atrial pressure, forcing the foramen ovale to close. It then fuses shut, becoming the fossa ovalis.
10001008
c
To shunt oxygenated blood from the right side of the heart to the left side of the heart
QuestionChoice
The ductus arteriosus shunts blood from the left pulmonary artery to the arch of the aorta, bypassing the foetal lungs. This blood comes from 2 places: the deoxygenated superior vena cava and the oxygenated inferior vena cava (this blood has picked up oxygen from the maternal circulation in the placenta). In actuality, only some blood passes through the ductus arteriosum, with most of it passing through the foramen ovale. Within hours of birth, the withdrawal of maternal prostaglandins causes closure and eventual fibrosis of the ductus arteriosus, resulting in the ligamentum arteriosum.
10001006
a
To shunt partially oxygenated blood from the pulmonary circulation to the systemic circulation
QuestionChoice
Although the formation of the recurrent laryngeal nerve does occur inferior to the ductus arteriosus, and the descent of the fetal heart does necessitate the long path of the recurrent laryngeal nerve so it can return to its innervation targets in the 6th pharyngeal arch, this is not the function of the ductus arteriosus.
10001009
d
To guide the recurrent laryngeal nerve to its adult position
QuestionChoice
The ductus venosus shunts blood from the umbilical vein to the inferior vena cava, and is inferior to the liver. This closes within 2-18 days of birth and fibroses to become ligamentum venosum.
10001007
b
To shunt oxygenated blood from the placental circulation to the inferior vena cava
QuestionChoice
Although the ductus arteriosus does physically join the left pulmonary artery and arch of the aorta, its main role is to shunt blood from the pulmonary circulation to the systemic circulation.

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10001010
e
To maintain the relative positions of the vessels within the mediastinum
Concept
Chapter
2693
3867
Foetal Circulation
Topic
159
Cardiovascular physiology
12748
What is the anti-natal function of the ligament found in adults at the same spinal level as the sternal angle?
a