12: Heart Development Flashcards
Causes of heart defects
Single gene mutations, chromosomal anomalies, teratogens, 85% multifactorial
The heart is the first what in the embryo?
First functioning organ
AGM stands for?
Aortic-gonadal-mesonephric
EPC stands for?
Endothelial precursor cells
Angiogenesis
Budding and sprouting of new vessels from existing ones
Intussusception
Splitting
How does the first aortic arch form?
Cranial ends of developing dorsal aorta are dragged centrally along with the heart -> forms a loop
Inflow of blood into the primitive heart is from what three vessels?
Common cardinal veins, vitelline veins, umbilical veins
Cardiac jelly
ECM between endocardium and myocardium
What forms the LV and RV?
Primitive ventricle -> LV
Outflow tract -> RV
When does rhythmic contraction and blood flow begin in fetal heart?
Contraction: day 22
Blood flow: day 24
Three veins that drain into the sinus horns and their sources of blood
- Umbilical V: placenta blood, O2 rich
- Vitelline V: blood from gut
- Common cardinal V: blood from head and trunk
First major step required for cardiac sept action
Cardiac looping
Three tissues that have to interact for maintenance of cardiogenic mesoderm proliferation for the second heart field
NCCs + pharyngeal arch mesoderm + pharyngeal arch endoderm
Crista terminalis
Junction between pectinate of RA and smooth walled part of RA (sinus venarum)
What two structures form the SA node? AV node?
Right sinus horn + right common cardinal vein; AV node comes from similar tissue in left sinus horn
ECT stands for?
Endocardial cushion tissue
What tissue type forms the tricuspid and bicuspid valves?
Endocardial cushion tissue
How does septum primum act as a one way flutter valve?
Allows RA blood to enter LA, but not the opposite direction
Steps in heart blood flow after first breath at birth
- Pulm circulation opens -> increased blood flow thru lungs -> into LA
- Pressure increase in LA -> R sided pressure decreases -> L sided pressure will now be higher
- septum primum driven against septum secundum -> foramen oval shuts
Partitioning of outflow tract
Common lumen divided into two tubes -> aorta connected to LV + pulmonary A connected to RV
Myocardialization
Outer myocardial wall is thinned as some myocardial cells begin to be replaced by cushion cells in specific areas -> helps form muscular interventricular septum
What provides primorida for semilunar valves of aorta and pulmonary trunk?
Spiraling ridges at truncus/conus junction
Sinus inversus
Complete reverse symmetry of heart and GI organs, not fatal and can be asymptomatic
Situs ambiguous
Reversal of some organs, can be problematic
Visceroatrial heterotaxia is a form of what?
Situs ambiguous
Visceroatrial heterotaxia
Heart and GI tract asymmetrically arranged from one another -> problems w/ inflow and outflow tract development
Probe latency
If foramen ovale does not completely close
Two causes of ostium II or high atrial septal defect
- Excess absorption of septum I
2. Inadequate development of septum II
