Lecture 13 10/17/23 Flashcards
What are two important characteristics of the fetus?
-lungs are non-functional
-placenta allows for nutrient/waste exchange
What are the characteristics of the umbilical arteries?
-originate on the internal iliac arteries
-take blood from fetus to placenta
What do the umbilical arteries become in adults?
round ligaments of the bladder
What is the role of the umbilical vein?
take blood from placenta to fetus
What does the umbilical vein become in adults?
round ligament of the liver
What is the role of the ductus venosus?
allow blood to bypass the liver
Why does the ductus venosus bypass the liver?
because the blood passing through it does not need to be filtered
What does the ductus venosus become in adults?
ligamentum venosum
Why is the hepatic portal vein blood filtered in the fetus?
to keep the filtration system functional
What are the characteristics of fetal lungs?
-collapsed
-blood vessels are open
-need some circulation
-collapse provides resistance to blood flow
What does the foramen ovale become in adults?
fossa ovalis
What are the characteristics of the foramen ovale?
-right to left shunt
-collapsed lungs create higher pressure in RA than LA
-one-way valve
What are the characteristics of the ductus arteriosus?
-right to left shunt
-takes excess blood from pulmonary artery to aortic arch
What does the ductus arteriosus become in adults?
ligamentum arteriosum
What happens when a neonate takes its first breath?
-resistance through the lungs drops
-oxygen content in the blood rises
What happens as a result of more blood coming into the LA after birth?
-pressure in the LA increases
-foramen ovale is forced closed
How does oxygen impact the fetal structures?
-increased O2 tension causes contraction of the special smooth muscle in the ductus arteriosus, ductus venosus, umbilical vein, and umbilical arteries
-this contraction causes the structures to close off
What does it mean for a structure to be probe patent?
-it appears closed, but a probe can still be pushed through
-structure isn’t fully sealed
How long does it take for the fetal structures to fully close?
about 2 weeks
What allows the fetal structures to fully close?
development of scar tissue
What is the falciform ligament?
fatty structure that surrounds the umbilical vein
What is the median ligament of the bladder?
peritoneal flap over the umbilical arteries
Why is it okay that the majority of the blood circulating through the fetus is deoxygenated?
the fetus does not have a need for a lot of oxygen because it is not moving much
How many sources contribute deoxygenated blood to circulation?
four
