11/14/2014 Gross Anatomy Development of the Heart Jeffrey Amack Flashcards
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:
Laterality defects
When do heart cells migrate into lateral plate mesoderm to form the primary heart field?
Gastrulation
Paired endocardial tubes fuse to form the:
Primitive heart tube
Name a common defect of heart looping that contributes to many malformations
Dextrocardia
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?
- septation of the primitive atrium
- atrioventricular valve formation
- septation of the outflow tract
- septation of the primitive ventricle
What occurs in the septation of the primitive atrium?
- The septum primum extends towards the endocardial cushions in the atrioventricular canal.
- 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).
- Non-closing of the foramen ovale
- Ostium secundum defect
- Endocardial cushion tissue defect
- Common atrium defect
How is the atrioventricular valve formed?
The endocardial cushions of the right and left AV canals fuse.