Development of Heart
What week does the heart start to function?
The embryo initially divides into two cavities; These are?
What connects the two embryonic cavities to the embryo?
What does the connecting stock evolve into?
Blood islands encompass the embryo in the what?
Blood islands eventually fuse to form what?
Fusing blood islands fuse to form blood vessles in the trophoblast and the what?
Tertiary Chorionic Villus
What is the mesoderm?
One layer of the primary germ cells and is responsible for connective tissue
Which end does the heart begin to form from?
Cranial (Head) end
What is the cardiogenic area?
Small group of mesodermal cells responsible for heart formation forming a pair of elongated strands called cardiogenic cords
How do the cardiogenic cords form the heart?
This is called the Primitive Heart Tube
Where can blood islands be found?
Surface of yolk sack
Cavities form between the blood islands. Why?
Do give hollow tubes - creating vessels
What is the pericardial coelom?
Section of the cardiogenic area that folds to surround the heart to create the pericardial sack
What are the endothelial strands known as in early development?
Why does the Oropharyngeal membrane fold posterior to the brain?
Different rates of growth
What is cardiac jelly?
Gelatinous connective tissue
What is the endocardium developed from?
What is the myocardium developed from?
How do we know the arterial end of the heart tube?
Its where blood exits
How do we know the venous end of the heart tube?
Its where blood enters
What does the sinus venosus develop into?
What does the bulbis cordis develop into?
What are the 5 main regoins of the developing heart?
Function of sinus venosus?
Receive blood from all veins in embryo
What does the atrium develop into?
Right and Left atrium
What does the ventricle develop into?
What does the truncus arteriosus develop into?
Ascending aorta and pulmonary trunk
Elongation causes folding of the tubes into the heart: how?
Atrial and venous ends are confined by the pericardium
What is the job of the cardiac jelly?
Seprates epicardium, myocardium and endocardium
What are the 3 pairs of veins that drain into the heart?
What do the vitelline veins do?
Return poorly oxygenated blood from the yolk sac
What do the umbillical veins do?
Carry well oxygenated blood from the chorionic villi of the embryonic placenta
What do the cardial veins do?
Return poorly oxygenated blood from the body of the embryo
How does the ductus venosus effect the liver?
Develops in liver connecting the umbilical vein to the IVC, meaning no blood travels through the hepatic capillary network
Which is the only vein to carry oxygenated blood?
What muscle and muscle movement give rise to the first contraction?
What are endocardial cushions?
Pinching of endocardium to form atrioventricular canals
What is the foramen ovale?
Opening in the interatrial septum (IAS)
What is the septum primum?
Upper most region of the IAS
What is the foramen primum?
The lowst hole in IAS
What is the foramen secundum?
The highest hole
What is the process of Foramen Ovale?
Septum primum begins to form downwards
Foramen primum begins to form upwards
Foramum primum fuses with endocardial cushions (closed)
Septum sarcundum (upper limb) begins to form downwards
Septum sarcundum (lower limb) begins to form upwards
Creates a foramen ovale
Septum primum degenerates
Valve is created - foramen ovale
How is the foramen ovale closed?
Increase in LA pressure compared to right - fusion
How to pulmonary veins associate with LA?
Grow independently onto LA
Name 3 shunts and their purpose during development:
Foramen Ovale - R - L atrium
Ductus arteriosis - Pulm Trunk - Aorta
Ductus Venosis - Umb Vein - IVC (bypasses liver)
What are the 3 different types of ASD?
Ostium secumdum - Middle Septum
Ostium Primum defect (endocardial cushion defect) - Lower Septum
Sinus Venosus Defect - Roof of Septum
What are the 4 structural complications with the heart in tetralogy of Fallot
Enlarged R Ventricle
Anterior deviation of the aorta
What is a patent ductus arteriosis?
Blood vessel between the aorta and pulmonary trunk remains open, causing a back flow of blood into the R ventricle
Development of Heart