Development of the Cardiovascular System Flashcards
In the embryo, what does the heart look like?
the heart is a simple tube with one atrium and one ventricle
do the lungs function in an embryo?
no - gas exchange takes place at the placenta
what happens at birth?
the baby has to switch immediately from one gas exchange surface to another
how is the pulmonary circuit developed?
the single atrium and ventricle must be subdivided, whilst still allowing blood from placenta to reach the body
in the heart of the embryo, what lies between the two atria of the heart?
the foramen ovale
in the heart of an embryo, what joins the pulmonary artery and the aorta?
the ductus arteriosus
what is the foramen ovale?
a gap in the interatrial wall
by when are the atrium and ventricle partly subdivided?
12 weeks
what does the umbilical cord carry?
oxygenated blood from the placenta to the inferior vena cava
how does oxygenated blood pass through the heart?
blood enters the right atrium through the inferior vena cava and passes across the foramen ovale to the left atrium then into the left ventricle to the aorta
how does deoxygenated blood pass through the heart?
deoxygenated blood from the head, arms and thorax enters through the superior vena cava and also enters the right atrium. most passes across the atrium and into the right ventricle. the blood then enters the pulmonary artery, but bypasses the lungs via ductus arteriosus to the aorta.
in an adult heart, what is the remnant of the foramen ovale called?
fossa ovalis (in right atrium)
describe fetal circulation.
oxygenated blood enters fetus from placenta in the umbilical vein. it is shunted past the liver and into the IVC via the ductus venosus. the IVE enters the right atrium. IVC blood passes through the foramen ovale to the left atrium, left ventricle, aorta and the arteries to the developing brain. deoxygenated blood enters the heart through the SVC and then passes to the right ventricle and pulmonary artery. the ductus arteriosus carris the SVC blood from the pulmonary artery to the aorta to bypass the lungs. deoxygenated blood from the body returns to the placenta via umbilical arteries.
what happens at birth?
the lungs open, the pulmonary circuit opens and blood pressure increases in the left atrium. this increase in pressure closes the foramen ovale. there is a change in blood o2 levels and blood flow closes the ductus arteriosus. the umbilical cord is cut and the placenta is ejected.
