Flashcards in 11/14/2014 Gross Anatomy Development of the Heart Jeffrey Amack Deck (49):
What percentage of births have a malformation of the heart?
1% of live births and 10% of all fetuses
How is the primary heart field formed in development?
Progenitor cells migrate through the primitive streak and into the lateral plate mesoderm to form the primary heart field.
What signals induce the primary heart field to form?
Signals from the endoderm, ie BMP 2 and 4, WNT inhibitors, NKX-2.5
What is formed in development when the endocardial tubes fuse?
The primitive heart tube, about 20-22 days gestation
What forms the heart outflow tracts and the lengthening of the heart tube?
Secondary heart field
The left ventricle is formed by:
The cardiac crescent
What is the primary developmental source of the right ventricle, and the atria?
The secondary heart field
Several congenital heart defects are associated with:
When do heart cells migrate into lateral plate mesoderm to form the primary heart field?
Paired endocardial tubes fuse to form the:
Primitive heart tube
Name a common defect of heart looping that contributes to many malformations
Left-right patterning of the heart is dependent on what process?
"Looping morphogenesis" of the heart tube
Days 28-37 of gestation see what major heart developmental milestones?
1. septation of the primitive atrium
2. atrioventricular valve formation
3. septation of the outflow tract
4. septation of the primitive ventricle
What occurs in the septation of the primitive atrium?
1. The septum primum extends towards the endocardial cushions in the atrioventricular canal.
2. Then, the ostium primum closes, the ostium secondum opens and the septum secondum forms
What divides the atrioventricular (AV) canal?
The AV septum, after the septation process
What is the most dangerous consequence of an atrial septal defect?
Intracardial shunting of blood, for example from the right atrium to the left atrium, which would eventually send non-oxgenated blood back out to the body
30-40% of congenital heart defects discovered in adulthood are:
Atrial septal defects (ASDs)
Name the common atrial septal defects (ASDs).
1. Non-closing of the foramen ovale
2. Ostium secundum defect
3. Endocardial cushion tissue defect
4. Common atrium defect
How is the atrioventricular valve formed?
The endocardial cushions of the right and left AV canals fuse.
Muscle cords in the heart become what two structures, in the formation of the atrioventricular valve?
Papillary muscles (at base) and chordae tendinae
In atrioventricular valve formation, the left AV valve becomes __1__ and the right AV valve becomes the __2__.
1. bicuspid (mitral) valve
2. tricuspid valve
Outgrowths of tissue called ____ can fuse to divide a lumen.
What forms the atrial septum?
The septum primum and the septum secundum, when they fuse with the atrioventricular septum.
What two openings in the atrial septum allow blood flow between the two atria during fetal deveopment?
1. Foramen ovale
2. Ostium secundum
Why do the bicuspid and tricuspid valves form?
Left (bicuspid) and right (tricuspid) atrioventricular valves develop to prevent backflow of blood when the ventricles contract.
What occurs in the septation of the outflow tract?
1. Endocardial cushions fuse to form a conotruncal septum.
2. Neural crest cells contribute to the conotruncal septum formation
3. The conotruncal septum spirals along the outflow tract, the aorta and pulmonary trunk twist around one another.
Name two common defects of the outflow tract.
1. Persistent truncus arteriosis
2. Transposition of the great arteries
What occurs during the septation of the ventricle?
Muscular interventricular septum fuses with conotruncal septum and AV septum to form the membranous interventricular septum.
What is the most common congenital heart defect?
A ventricular septal defect, mostly in the muscular region. Many resolve with growth. The more dangerous VSD involved the membrane--large VSDs cause left-to-right shunts that increases pulmonary blood flow and pulmonary hypertension
Cushions in the outflow tract are remodeled in development to form what?
How is the right ventricle connected to the pulmonary artery during septation of the outflow tract?
The conotruncal septum spirals to create these connections.
How is the left ventricle connected to the aorta during septation of the outflow tract?
The conotruncal septum spirals to create these connections.
Failure to completely separate the outflow tract results in:
Persistent truncus arteriosis.
Failure of the conotruncal septum to spiral results in:
Transposition of the great arteries.
Where do semilunar valves form during development of the heart?
Semilunar valves form between the ventricles and the great arteries.
In fetal circulation, oxygenated blood flows from the placenta where?
Blood flows from the placenta to the inferior vena cava through the ductus arteriosis.
In fetal circulation, the inferior vena cava shunts blood through the ___ into the left atrium.
After blood flows into the left atrium in fetal circulation, where does it go?
Left ventricle, then out to the fetal body
What opening in fetal circulation sends blood from the pulmonary artery to the aorta?
In fetal circulation, how does deoxygenated blood return to the placenta?
In fetal circulation, when do pulmonary vessels begin to function, and pulmonary resistance decreases?
At birth, the foramen ovale closes, and the septum primum fuses with what?
The septum secundum
Besides the foramen ovale, what other fetal circulatory structures close at birth?
Umbilical arteries, ductus venosus and umbilical vein
At birth, the foramen ovale becomes what?
At birth, the ____ becomes the ligamentum ateriosum
At birth, the ductus venosus becomes?
The ligamentum venosum
What is patent ductus arteriosis?
If the ductus arteriosis does not close, oxygenated blood from the aorta and the deoxygenated blood from the pulmonary artery
During fetal circulation, the ductus venosus at the ____ regulates blood flow from the placenta to the inferior vena cava