Fetal Circulation
Kevin Kabuga
BIO 160
10/28/14
Adult vs. Fetal Circulation
CRN 93954
Prof. Kifle
In adult circulation sequence, non-oxygenated blood enters the right atrium via the inferior and superior vena cava. The increase level of blood in the right atrium causes the tricuspid valve to open and drain the blood to the right ventricle. Pressure of blood in the right ventricle causes the pulmonic valve to open and non-oxygenated blood is directed to the pulmonary artery then to the lungs. The exchange of gases occurs in the lungs. Highly oxygenated blood is returned to the heart via the pulmonary vein to the left atrium. From the left atrium the pressure of the oxygenated blood causes the mitral valve to open and drain the oxygenated blood to the left ventricle. Left ventricle then pumps the oxygenated blood that opens the aortic valve. Blood is then directed to the ascending and descending aorta to be distributed in the systemic circulation
Fetal circulation differs significantly from adult circulation in that the fetal lungs are mostly bypassed. The placenta provides the developing embryo with food and oxygen and removes carbon dioxide and nitrogenous wastes. Blood rich in oxygen enters the embryo via the umbilical vein and passes through the liver via a channel known as the ductus venosus and then to the right atrium via the caudal vena cava. Blood low in oxygen returning from the head via the cranial vena cava also enters the right atrium. From the right atrium, blood can follow one of two pathways. The foramen ovale, an opening in the septum between the right and left atria, allows blood to pass to the left atrium, then to the left ventricle, from which it is pumped through the aorta to the body. It is largely the oxygen-rich blood which entered the heart via the caudal vena cava which follows this route. Some blood, mostly the deoxygenated blood from the superior vena cava, is pumped into the right ventricle and into the pulmonary artery. It bypasses the lungs
BIO 160
10/28/14
Adult vs. Fetal Circulation
CRN 93954
Prof. Kifle
In adult circulation sequence, non-oxygenated blood enters the right atrium via the inferior and superior vena cava. The increase level of blood in the right atrium causes the tricuspid valve to open and drain the blood to the right ventricle. Pressure of blood in the right ventricle causes the pulmonic valve to open and non-oxygenated blood is directed to the pulmonary artery then to the lungs. The exchange of gases occurs in the lungs. Highly oxygenated blood is returned to the heart via the pulmonary vein to the left atrium. From the left atrium the pressure of the oxygenated blood causes the mitral valve to open and drain the oxygenated blood to the left ventricle. Left ventricle then pumps the oxygenated blood that opens the aortic valve. Blood is then directed to the ascending and descending aorta to be distributed in the systemic circulation
Fetal circulation differs significantly from adult circulation in that the fetal lungs are mostly bypassed. The placenta provides the developing embryo with food and oxygen and removes carbon dioxide and nitrogenous wastes. Blood rich in oxygen enters the embryo via the umbilical vein and passes through the liver via a channel known as the ductus venosus and then to the right atrium via the caudal vena cava. Blood low in oxygen returning from the head via the cranial vena cava also enters the right atrium. From the right atrium, blood can follow one of two pathways. The foramen ovale, an opening in the septum between the right and left atria, allows blood to pass to the left atrium, then to the left ventricle, from which it is pumped through the aorta to the body. It is largely the oxygen-rich blood which entered the heart via the caudal vena cava which follows this route. Some blood, mostly the deoxygenated blood from the superior vena cava, is pumped into the right ventricle and into the pulmonary artery. It bypasses the lungs
Cited: 1. Long WA. Developmental cardiac anatomy. In: Long WA, editor. Fetal and Neonatal Cardiology.Philadelphia: WB Saunders Co; 1989. pp. 3–16. 2. Berglund G. Studies of circulation in the neonatal period. Acta Paediatr. 1955; 103:138–9. 3. Arey LB. Fetal circulation and changes at birth. In: Arey LB, editor. Developmental Anatomy.Philadelphia: WB Saunders Co; 1954. pp. 387–9. 4. Rudolph AM, Drorbaugh JE, Auld PA, et al. Studies on the circulation in the neonatal period. The circulation in respiratory distress syndrome. Pediatrics. 1961; 27:551–6. 5. Lind J, Wegelius C. Changes in the circulation at birth. Acta Paediatr. 1952; 42:495–6.