CV Development-02 Flashcards
fetal circulatory system
many modifications to CV circuit because the lungs are not yet developed nor many other organs for waste extraction
what are the 3 shunts in the fetal circulation?
ductus arteriosus, ductus venosus, foramen ovale
what type of circuit is the fetal circulation?
2 open circuits operating in parallel
what type of circuit is the adult circulation?
2 closed circuits arranged in series
where is pressure greater in fetal circulation?
right side
where is pressure greater in adult/postnatal circulation?
left side
postnatal circulatory system
pulmonary circuit on right side returning deoxygenated blood to lungs and systemic circuit delivering oxygenated blood to the tissues
what is the purpose of shunts in fetal circulation?
so that oxygenated blood from the placenta can quickly reach/bypass to the fetus’ systemic circuit quickly to feed tissues
umbilical vein
delivers oxygenated blood from the placenta to the fetus
ductus venosus
connects the umbilical vein to the IVC, bypassing the liver
ductus arteriosus
diverts blood from the pulmonary trunk to the aorta
foramen ovale
connects the two atria in the fetal heart, diverting blood from the RA to the LA
left and right umbilical arteries
from systemic circuit; located next to the urinary bladder, go up through umbilicus and wrap around umbilical vein to send deoxygenated blood away from fetus
what does the foramen ovale become?
fossa ovalis
what does the ductus arteriosus become?
ligamentum arteriosum
what does the ductus venosus become?
ligamentum venosum
what do the umbilical arteries become?
medial umbilical ligaments
what does the umbilical vein become after closure?
ligamentum teres
tubular heart development
- two tubular hearts fuse together 2. bulges/sacculations 3. saccular tube elongates (heart prominence) 4. valves form 5. two sides of tube come together and start eating away walls to create chambers and set up valves
what important structure does the truncus arteriosus become?
pulmonary trunk and aorta
what important structure does the bulbus cordis become?
right ventricle
what important structure does the ventricle become?
the left ventricle
what important structure does the atrium become?
mostly the LA and parts of the RA, right and left auricles
what important structure does the sinus venosus become?
much of the RA, SA node, coronary sinus
division of the truncus arteriosus
lateral ridges of the TA form the aorticopulmonary septum and it will spiral 180º when completely formed
where do the SL valves form?
at the base of the truncus arteriosus
persistent truncus
aorticopulmonary septum fails to form, mixed blood from L and R ventricles creating issues w/ ability to oxygenate blood and deliver this blood to the body (similar to 3 chambered hearts)
transposition of the great vessels
aorticopulmonary septum forms, but fails to spiral 180º; this condition is fatal unless the following are also present: PDA, ASD, VSD
valve stenosis
due to unequal partitioning, a result of deviation of the aorticopulmonary septum (one sided expanded, one side stenosed)
patent ductus arteriosus (PDA)
ductus arteriosus remains open, can lead to volume overload in the pulmonary circuit, increased pulmonary blood flow may cause pulmonary edema – treated by surgically stitching
atrial septal defect (ASD)
foramen oval fail to close
formation of interatrial septum
2 phases: wall forms first, second wall forms behind it to form opening and flap; septum primum (1st wall), foramen primum (1st hole), foramen secondum (2nd hole), septum secundum (2nd wall)
septum primum (1st wall)
begins at top of left and right atrium and grows toward center of heart
foramen primum (1st hole)
keeps developing down heart, once it starts reaching the center of the heart, upper portion of wall starts developing holes - foramen secundum (2nd hole)
septum secundum (2nd wall)
forms in behind 1st wall, does not form completely and also has hole; 1st wall forms flap over 2nd wall’s hole (foramen ovale) called valve of foramen ovale
what are 2 major vascular changes after birth?
- increased systemic resistance w/ loss of placenta
2. decreased pulm. vascular resistance w breathing
formation of interventricular septum
- wall begins forming at apex 2. grows toward fibrous skeleton; first part is true IV septum, final segment is membranous portion
formation of AV valves
form from stem cells found within bulges called cushions/swellings found around fibrous skeleton, 3 cushions for tricuspid valve and 2 for bicuspid
tetralogy of Fallot
pulmonary valve stenosis, overriding aorta, VSD, RV hypertrophy
