5. Truncus Arteriosus (roots AO & pulmonary arteries)
What is looping?
When does it occur?
Looping of heart tubes as they grow at a faster rate than the pericardium. Dextro=Rt=normal. Levo=left=malposition of vent or great vessels
Looping starts at day 24
Heart begins to beat at day _________.
Circulation of heart begins at day _____to____.
Sinus venosus - Lt horn becomes:
oblique vein of LA & coronary sinus
Sinus venosus Rt horn becomes:
Part of RA, IVC, SVC
What is the most posterior part of embryological heart
sinus venosus left horn
IAS forms between _____ & _____ day.
There are 3 events of IAS formation. Explain
1. Septum Primum (divides atrium to Lt & Rt sides)
2. Septum Secundum (forms superior portion of RA adjacent to septum primum; oval shaped opening persists
3. Fossa Ovalis (early remnants of sinus venosus tissue found @ jxn of IVC & SVC with RA)
Expain the events of Ventricular Septal Formation: (3)
1. Lateral aspect expanding faster than medial = med invagnation=gradually fuses to form a portion of IVS. Small opening @ level AV valves permits con't communication.
2. Muscular IVS forms passively by expansion of ventricle (27th day)
3. MMB IVS forms actively by growth of endocardial cushion (b/c it has a bigger job)
Explain the events of AV Canal Formation: (3)
1. 30-40 days - 4 mesenchymal swellings appear.
2. 2 endocardial cushions = septal TV leaflet & AMVL and a portion of inflow perimmb IVS
3. 2 lateral cushions = ATVL, PTVS, PMVL
The events of outflow tract formation are: (3)
1. Conus Cordis divides outflow tract into Rt & Lt.
2. 2 swellings in truncus arteriosus form septum dividing into AO and pulmonic and twist around each other as they expand therefore the spiral relationship(begins at distal end from truncus -->conus cordis
3. Tubercles on main truncus swelling responsible for formation of AO and pulmonic valves
3rd set of AO arches becomes the _____________________?
CCA & ICA
4th set AO arches becomes _____________________.
6th set AO arches becomes ___________________________.
Rt & Lt Pulmonary Arteries
The distal portion of 6th AO arch remains in connection to arterial system via ______________ ______________.
ductus arteriosus (pulmonary to systemic shunt)
Fetal Circulation Review: O2 blood from placenta returns IVC and shunts across the ___________.
3 weeks =
5-6 part primitive cardiac tube
carciac loop begins
all 4 chambers are complete
What is the cardiogenic region?
Horseshoe shaped region b/f endocardial cushion done forming valves.
What is the septum primum in an adult called?
Right atrium - atrial fold - helps direct O2 IVC blood across IAS to fetal circulation =