Page 21, Early Development, Devel. Physiol., Dr. D. Penney

Fetal Circulatory Pattern: (cont.)

The fetal circulatory pattern insures that blood of higher P02 and oxygen content reaches the brain; blood of lesser P02 and oxygen content reach the lower body.

Cardiac output is high in the fetus per kg body weight; therefore, a large blood flow reaches the placenta and fetal tissues.

The fetal pulmonary circulation has a high resistance, therefore blood flow to the lung is low; simply commensurate with the needs of the growing tissue. The lung is extracting oxygen from the blood at this time, not adding oxygen. This circulation is sensitive to oxygen, ie. the elevation in P02 that occurs at birth.

To review vascular resistance

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