f. Some of this blood reaches the myocardium by means of the coronary
arteries and some reaches the tissues of the brain through the carotid arteries.
g. The rest of the blood entering the right atrium, as well as the large proportion
of the deoxygenated blood entering from the superior vena cava, passes into the right
ventricle and out through the pulmonary artery.
h. Enough blood reaches the lung tissues to sustain them.
i. Most of the blood in the pulmonary artery bypasses the lungs by entering the
ductus arteriosus, which connects the pulmonary artery to the descending portion of the
aortic arch.
j. Some of the blood carried by the descending aorta leads to the various parts
in the lower regions of the body.
k. The rest of the blood passes into the umbilical arteries which branch from the
internal iliac arteries and lead to the placenta.
2-12. CHANGES CONTINUE IN CIRCULATION AFTER BIRTH
See figure 2-10.
Figure 2-10. Fetal circulation after birth.
2-14
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