cardiovascular changes at birth

Question 1

fetal circulation

Answer 1

3 shunts:
-foramen ovale
-ductus arteriosus
-ductus venous
streaming in the right atrium 
vasoconstriction in the pulmonary circulation

Question 2

foramen ovale

Answer 2

allows flow from the right atrium to the left atrium

Question 3

ductus arteriosus

Answer 3

carries blood from the pulmonary artery to the descending aorta

Question 4

ductus venosus

Answer 4

allows blood from the placenta to bypass the liver

Question 5

ductus arteriosus

Answer 5

pulmonary vasoconstriction:
-reduces blood flow to the lungs, diverting PA blood through the ductus arteriosus
-increases right atrial pressure, helping to keep the foramen oval open
deoxygenated blood in the DA joins the descending aorta to supply the lower body, thus preserving the brain’s oxygen supply

Question 6

pulmonary vasoconstriction

Answer 6

mediated by hypoxia
if hypoxia continues after birth, can lead to persistence of the fetal circulation
can occur later in life from chronic hypoxia to cause pulmonary hypertension

Question 7

ductus arterioles at birth

Answer 7

flow reverses and then ceases
the pulmonary and systemic circulation become separate , with the whole output of the right ventricle passing through the pulmonary circulation

Question 8

ductus arteriosus closure

Answer 8

patency in utero maintained by prostaglandin E2
closure normally occurs after birth within 2-3 days
it is the final event in the sequence