Exam 2 Lecture - Development of the Cardiovascular System Flashcards
Where does the right atrium receive blood from?
the caudal and cranial vena cava; system return
Where does the right ventricle send blood?
pushes it out through the pulmonary trunk and arteries to the lungs; pulmonary outflow
Where does the left atrium get blood from?
the pulmonary veins; pulmonary return
Where does the left ventricle send blood?
to the aorta, out to the rest of the body; systemic outflow
What is special about the relationship of the pulmonary trunk and the aorta?
they wrap around each other
True or False: the heart is the first organ to differentiate and the first organ to function
False: it is only the first organ to function
At what important developmental event does the 1st heat beat happen at?
the closure of the neural tube
In early development, what is the function of the heart?
move blood from extra embryonic vessels through the embryonic circulatory system
What is the heart in the first stage of embryonic development?
a cardiogenic plate
Where is the cardiogenic plate located at the beginning of its development?
outside of the embryo proper
What process brings the cardiogenic plate inside of the embryo proper?
body folding brings the cardiogenic plate inside by turning it 180 degrees
Where is the heart located in early development?
where the mandible is
What causes the first heart beat?
the two heart tubes within the cardiogenic plate spontaneously contract and then fuse
What is the pump of the early development heart considered?
simple peristaltic pump - contraction goes from caudal (inflow) to cranial (outflow)
What are the primitive heart regions?
sinous venosus, atrium, ventricle, bulbus cordis, truncus arteriosus, and bulbus cordis
What does the sinous venosus give rise to?
the left part becomes the coronary sinus, the right part becomes part of the wall of the atrium
What does the atrium become?
the left and right atria
What does the bulbus cordis become?
part of the right and a small part of the left ventricle
What does the truncus arteriosus and bulbs cordis become?
the ascending aorta and the pulmonary trunk
What does the ventricle become?
part of the right and left ventricle
What causes the rotation in the heart (cardiac loop)?
one part of the embryologic heart will grow faster than the other part causing rotation
How does the cardiac loop affect the location of the atria?
it helps it become dorsal to the ventricle
How does the cardiac loop affect the location of the ventricle?
puts the ventricle next to the bulbus cordus
How are the atrium and the ventricle connected?
via the atrioventricular canal
How are the endocardial cushions formed?
the heart begins to form a constriction between the atrium and the ventricle
What is the purpose of the endocardial cushion?
it divides the atrioventricular canal into two different sections
Why is atrial partitioning important?
because it will ensure that the developing animal can move blood from the right atrium to the left atrium
What are the structures that develop from atrial partitioning?
Septum 1 Foramen 1 Foramen 2 Septum 2 Oval foramen
What is the first structure to develop?
septum 1
What is the opening between septum 1 and the endocardial cushions called?
foramen 1
What happens to foramen 1?
IT GETS OBLITERATED as septum 1 continues to grow down and meet the endocardial cushion
What forms foramen 2?
an area of apoptosis
The septum 2 forms after foramen 2 forms, what forms within septum 2?
Foramen 3 (oval foramen)
How does blood flow beginning at the right atrium and ending at the left atrium in the embryonic heart?
flows from the right atrium through the oval foramen in between septum 1 and 2 and flow through foramen 2
Why is the pulmonary trunk and the aorta twisted around each other?
because during development, the endocardial cushions fuse together, but as you move down the atrioventricular canal, they are oriented differently causing a spiral septum dividing the outflow
What 3 things are vital to closing the intraventricular foramen?
the intraventricular septum, the spiral septum, the endocardial cushion
Ectopic cordis
when the heart is in an abnormal location
dextrocardia
the heart of the adult is a mirror image of normal
commonly seen in situs inversus
What are 3 common valvular defects?
stenosis, insufficiency, dysplasia
What are the defects associated with tetralogy of fallot?
intraventricular foramen is still open, pulmonary stenosis, dextroposition of aorta, right ventricular hypertrophy
What does embryo mean?
early development when we do not know what it is going to become
What does fetus mean?
once we know what it is going to become
How does blood flow through the fetus (right atrium route)?
Umbilical vein (high O2) to either (a) through the mass of the liver or (b) through the ductus venosus to the caudal vena cava (low O2) to the right atrium, through the oval foramen, between septum 1 and 2, through foramen 2, into the left atrium, to the left ventricle, out of the aorta, to the head, back to the aortic arch to the umbilical artery
If the blood does not go to the right atrium, how does the blood flow?
to the right ventricle, joined by the blood returning from the cranial vena cava, to the pulmonary trunk to the ductus arteriosus to the aorta to the aortic arch to the umbilical artery
What is considered things that the newborn has to ‘deal with’ at birth?
umbilical artery, ductus arteriosus, oval foramen, ductus venosus, umbilical vein
What happens to the umbilical artery at birth?
it is crushed when born and collapses and closes off
What happens to the ductus arteriosus at birth?
longest process of closure; a decrease in blood pressure, loss of PGE2 from the placenta, increase of oxygen concentration causing it to close
What happens to the oval foramen after birth?
an increase in blood pressure to the left atrium, a decrease of blood pressure of the right atrium; pushes septum 1 into septum 2 and hits off the flow of blood from the right atrium to the left causing it to close
How does the ductus venosus close?
usually closed at the time of birth, if not it closes like the umbilical vain; no blood flow, decrease of PGE2
How does the umbilical vein close?
shuts down when the vein no longer has blood flow from the placenta because the placenta provides PGE2
What is PGE2?
a potent vasodilator; when the production stops, the vein constricts
What are the structures of the cardiac loop in the basic embryo?
ventral aorta, dorsal aorta, aortic arches
How many aortic arches are there and what are their numbers?
5; 1,2,3,4,6
Why is there no 5th aortic arch?
because it rarely develops in mammals, found in lower vertebrates
What happens to the 1st and 2nd arches during development?
they degenerate
What is the function of the 3rd aortic arch during development?
to supply the head
What is the function of the 4th aortic arch during development?
to supply the rest of the body
What does the 3rd aortic arch contribute to?
the internal carotid artery
What does the left 4th aortic arch become incorporated into?
the aortic arch of the adult
What does the right 4th aortic arch become incorporated into?
the right subclavian
What does the right 6th aortic arch become incorporated into?
nothing, it degenerates
What does the left 6th aortic arch become incorporated into?
the ductus arteriosus
