Anatomy cardiac embryology I Flashcards
Cardiac Progenitor cells are derived from where? What do they give rise to?
Derived from intraembryonic mesoderm from the cranial third of the embryo. Give rise to the cardiac cresent (primary heart field)
Primary heart field gives rise to
atria, left ventricle, and part of the right ventricle
Secondary heart field is derived from where? Gives rise to what?
Derived from splanchnic mesoderm. Forms remainder of the right ventricle and outflow tract (conus cordis and truncus arteriosus)
Formation of major layers of the heart
1.) Elongated vascular elements formed from the heart cresent = endocardual tubes (stimulated by vegf) 2.) as lateral folding occurs the tubes fuse together 3.) endocardial tube becomes surrounded by splanchnic mesoderm giving rise to the myocardium 4.) epicardium is formed by population of mesothelial cells
Sinus Venosis
consists of confulent left and right sinus horns that receive blod from common cardinal veins
What forms the smooth walled portion of the right atrium and the coronary sinus
Sinus venosus and its horns
What forms the pectinated portions of the left and right artia
the primitive atrium
What Forms the right ventricle
Bulbus Cordis
The outflow tract consists of
1.) Conus arteriosus 2.) Truncus arteriosus
Fate of Conus arteriosus
becomes incorporated into the left and right ventricles
Fate of the Truncus aretriosus
eventually splits to form the ascending aorta and pulmonary artery
Describe cardiac looping
On day 23 heart elongates into a C-SHAPE. As it continues to elongates it becomes and S-SHAPE. End result is a 4 chamber heart
Division of the atrioventricular canal
end of the 4th week ENDOCARDIAL CUSHIONS develop on the walls of the AV canal separating it into left and right AV canals
Septum Primum
thin, crescent shaped membrane that grows from the roof of the primordial atrium towards the endocardial cushion - Leaves an opening called foramen primum.
Fate of the Septum Primum
Eventually fuses to the AV septum and closes the foramen primum. BUT right before this happens cells in the dorsal part of the septum go through apoptosis to create a new opening - foramen secundum
Foramen Secundum
forms in the septum primum as the foramen primum disappears. Allows shunting of blood from right atrium to left atrium
Septum Secundum
gows towards the AV septum covering most of the foramen secundum but stops just before reaching the septum leaving an oeping called the foramen ovale
what forms the valve of the foramen ovale
the caudal part of the septum primum
Role of valve of the foramen ovale
prevents left to right shunting of blood and closes the foramen ovale at birth
Fate of the sinus venousus horns (Left and right)
Right - smooth part of the right atrium (sinus venae cavae). Left- regresses and is tranformed into a small venous sac on the posterior wall of the heart = CORONARY SINUS
what forms the smooth walled protion of the left atrium
Primordial pulmonary veins
What forms the smooth walled portion of the right atrium
Right sinus venosus
Describe the partitioning of the ventricles
At week 4 the bulboventricular groove buldges in until it almost reaches the cushion (leaves the interventricular foramen). At the same time the myocardium begins to thicken and gives rise to trabeculae
Division of the truncus arteriossus gives rise to what structures
1.) Pulmonary Trunk 2.) Aorta
What causes the division of the truncus arteriosus
the fromation of the aorticopulmonary septum (spiral septum)
Development of the aorticopulmonary septum
formed by a series of bulbar and truncal ridges/cushions that spiral down from the level of the aortic valve by making a 180 degree turn towards the interventricular septum. Fuses with the newly formed membranous ventricular septum and completely closes the interventricular foramen.
Development of the semilunar valves
During the formation of the aorticopulmonary septum two small cushions of tissue develop within the wall of the outflow tract. Cushions become modified to fom aortic and pulmonary valves
Name the non-cyanotic congenital heart defects
1.) Ventricular Septal Defect 2.) Ostium Secundum Defect 3.) Cor triloculare biventriculare 4.) Aortic Stenosis
Name the cyanotic congenital heart defects
1.) Tetrology of Fallot 2.) Transposition of the great vessels 3.) Perisitent truncus aretriosus 4.) Tricuspid atresia 5.) Hypoplastic left heart syndrome
What is the most common congenital cardiac malformation
Ventricular septal defect
Ventricular septal defect
involves the membransous portion of the septum
Ostium secundum defect
leaves a large opening between the atria. Due to excessive resportion of septum primum or inadequate development of septum secundum
Cor Triloculare Biventriculare
complete absence of the atrial septum
Aortic Stenosis
caused by fusion of the cusps of the aortic valve
Tetrology of Fallot
due to unequal division of the conus because of displacement of the aorticopulmonary (spiral) septum.
What for alteraltions are seen in tetrology of fallot
1) Pulmonary infundibular stenosis 2.) Right ventricular hypertrophy 3.) Overriding aorta that arises durectly above the septal defect 4.) Large IV septal defect (mneumonic: PROV)
Transposition of the great vessels
occurs when aorticopulmonary septum fails to follow its course and runs straight down resulting in the aorta originating from the right ventricle and the pulmonary trunk originating from the left ventricle
Persistent truncus arteriosus
Failure of fusion of the bulbar and truncal ridges. ALWAYS accompanied by defective IVS. Undivided truncus recieves blood from both sides of the heart
Tricuspid atresia
characterized by either the absence of or the fusion of tricuspid valves resulting in obliteration of right atrioventricular orifice
Hypoplastic left heart syndrome
left ventricle is underdeveloped. Typicaly there is a large PFO (patent foramen ovale), PDA (Patent ductus arteriosus), hypoplastic ascending aorta/aortic arch and mitral/aortic valves
Dextrocardia
the heart is on the right because the heart tube loops left
Ectopia cordis
the heart lies on the surface of the chest due to failure of closure of the ventral body wall
