What happens in fetal pig circulation?

Answer 1

There are three major differences between normal circulatory pathways and fetal circulation. First, as you have already learned, oxygenated blood that is high in nutrients obtained from the placenta enters the fetal pig body not from lung capillaries, but via the umbilical vein to the ductus venosus in the liver. The ductus venosus leads in turn to the caudal vena cava, through which the blood enters the right atrium. The second major difference is the presence in fetal pigs of an opening between the heart atria (through the interatrial septum), called the foramen ovale. Oxygenated blood entering the right atrium from the caudal vena cava tends to pass through the foramen ovale into the left atrium, thus bypassing the pulmonary circulation system. Deoxygenated blood from the cranial vena cava enters the atrium anteriorly and flows into the right ventricle. As a result of this arrangement, there is little mixing of oxygenated and deoxygenated blood. A third major difference is the action of the ductus arteriosus vessel, which shunts blood away from the fetal pig's lungs and into the aorta. Highly oxygenated blood in the left atrium is pumped into the left ventricle and then into the aorta. It then enters the coronary arteries and the arteries of the head region, before mixing with deoxygenated blood from the ductus arteriosus and the lower systemic circulation.