5.11

What are the immediate consequences of the cessation of umbilical blood flow after birth

1. It causes a cessation of flow into the ductus venosus, 2. a fall in pressure in the right atrium 3. closure of the foramen ovale

Name and describe the temporary structures that enable fetal circulation.

1. Ductus venosus: connects the umbilical vein to the inferior vena cava 2. Foramen ovale: is an opening between the right and left atria. 3. Ductus arteriosus: leads from the bifurcation of the pulmonary artery to the descending aorta 4. Hypogastric arteries: branch off from the internal iliac arteries and become the umbilical arteries when they enter the umbilical cord

What happens when the newborn takes the first breath?

1. The lungs inflate and there is a rapid fall in pulmonary vascular resistance. 2. The ductus arteriosus constricts due to bradykinin released from the lungs on initial inflation

outline the course of fetal circulation

a. oxygenated blood from the placenta travels to the fetus in the umbilical vein. b. the umbilical veins divide into two branches: one that supplies the portal vein in the liver, the other the ductus venosus joining the inferior vena cava. c. most of the oxygenated blood that enters the right atrium passes across the foramen ovale to the left atrium and from there here into the left ventricle, and then the aorta. d. The head and upper extremities receive approx. 50% of this blood via the coronary and carotid arteries and the subclavian arteries. The rest of the blood travels down the descending aorta, mixing with deoxygenated blood from the right ventricle. e. deoxygenated blood collected from the upper parts of the body returns to the right atrium in the superior vena cava. f. blood that has entered the right atrium from the superior vena cava and inferior vena cava passes into the right ventricle. g. a little blood travels to the lungs in the pulmonary artery, for their development. h. most blood passes through the ductus arteriosus into the descending aorta. This blood though low in oxygen and nutrients is sufficient to su0ply the lower body. i. it's by this means that deoxygenated blood travels back to the placenta via the internal iliac arteries which lead into the hypogastric arteries which lead into the umbilical arteries (Myles, 162).

What happens to the temporary structures of fetal life?

a. the umbilical vein becomes the ligamentum teres b. the ductus venosus becomes the ligamentum venosum c. the ductus arteriosus becomes the ligamentum arteriosum d. the foramen ovale becomes the fossa ovalis e. the hypogastric arteries are known as the obliterated hypogastric arteries except for the first few centimeters, which remain open as the superior vesicle arteries