The fetal lungs are collapsed, and blood passes from the right atrium directly into the left atrium through the foramen ovale: an open conduit between the paired atria, or through the ductus arteriosus: a shunt between the pulmonary artery and the aorta.
By Deborah Leader, RN. Updated January 21, 2016. Hypercapnia is a condition that occurs when there is too much carbon dioxide in the blood. While it is sometimes caused by things such as hypoventilation or a narcotic drug overdose, a much more common cause is COPD. If you have COPD, it's important to know the hypercapnia symptoms, as well as the treatments available.
Gaseous exchange occurs in the alveoli by simple diffusion. The blood flowing past the alveoli is rich in carbon dioxide and very poor in oxygen. The gas molecules naturally flow in the direction of... Gaseous exchange occurs in the alveoli by simple diffusion. The blood flowing past the alveoli is rich in carbon dioxide and very poor in oxygen.