What causes cardiac looping during heart development?
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The bulbus cordis and ventricle grow faster than other regions of the heart.
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What causes cardiac looping during heart development?
The bulbus cordis and ventricle grow faster than other regions of the heart.
What percentage of blood from the descending aorta goes to the umbilical arteries to be oxygenated in the placenta?
65%
What prevents backflow of blood through the foramen ovale (FO) before birth?
The valve of the foramen ovale (FO), formed by the septum primum (SP), prevents backflow.
What structures are formed by the muscular bundles on the walls of the ventricles?
The muscular bundles form the trabeculae carneae, tendinous cords, and papillary muscles.
What is the first step in the development of blood vessels?
Mesenchymal cells differentiate into angioblasts.
What causes the spiraling of the bulbar and truncal ridges?
The streaming of blood from the ventricles.
What causes a patent foramen ovale?
Incomplete adhesion of the valve of the foramen ovale to the septum secundum after birth.
What happens to the umbilical vein after birth?
It becomes the ligamentum teres, a round ligament of the liver.
How does oxygenated blood reach the atrium after the foramen primum closes?
Perforations form in the septum primum, which enlarge to form the foramen secundum.
What is the interventricular foramen (IF) and when does it close?
The interventricular foramen (IF) forms between the muscular interventricular septum (MIS) and the endocardial cushions (EC), allowing blood flow between the left and right ventricles. It closes by the end of the 7th week of development.
What triggers the development of blood vessels in the embryo?
An increase in oxygen and nutritional requirements of the embryo.
What process results from the formation of blood islands due to the aggregation of angioblasts?
Vasculogenesis.
What structures are involved in the partitioning of the primordial atrium?
The septum primum (SP) and septum secundum (SS).
What is an atrial septal defect (ASD)?
A congenital heart disease characterized by a hole in the wall between the two atria.
What results from the fusion and spiraling of the bulbar and truncal ridges?
The formation of a spiral aorticopulmonary septum (AS).
Name a derivative of the fetal vascular structure ductus arteriosus.
Ligamentum arteriosum.
What leads to the transposition of the great arteries (TGA)?
Failure of the aorticopulmonary septum to pursue a spiral course.
What is the septum primum?
A membrane that grows from the roof of the primordial atrium towards the endocardial cushion.
What causes the functional closure of the foramen ovale (FO) after birth?
The increase in pressure in the left atrium (LA) as the lungs begin to function.
What is the foramen ovale?
An opening formed when the septum secundum overlaps or covers part of the foramen secundum.
Why does the ductus arteriosus remain patent during fetal life?
Due to the lower oxygen content of blood passing through it and the actions of prostaglandins.
What happens after endothelial-lined cavities form?
They fuse to become blood vessels.
What structures does the tubular heart form through elongation and constriction?
Bulbus cordis, which includes the truncus arteriosus, conus arteriosus, and conus cordis.
What is dextrocardia?
A congenital heart disease where the heart is situated on the right side of the body.
What is a ventricular septal defect (VSD)?
A congenital heart disease characterized by a hole in the wall between the two ventricles.
What is the consequence of the formation of the spiral aorticopulmonary septum?
It enables the pulmonary trunk to twist around the aorta.
What are the manifestations of a large ventricular septal defect?
Difficulty in breathing and cardiac failure during infancy.
What is Patent Ductus Arteriosus (PDA)?
A condition where the ductus arteriosus fails to close after birth, causing blood to be shunted from the aorta to the pulmonary trunk.
Name the three shunts used in fetal circulation.
Ductus venosus, foramen ovale, and ductus arteriosus.
Which organs do not function until birth in fetal circulation?
Lungs, kidneys, and gastrointestinal organs.
What congenital anomaly results from the failure of the aorticopulmonary septum to spiral?
Transposition of the great arteries.
What happens to the foramen primum as the septum primum grows?
It gradually becomes smaller until it disappears.
What forms the foramen secundum (FS) during the partitioning of the primordial atrium?
Perforations in the septum primum (SP) enlarge to form the foramen secundum (FS).
What are the two main circulatory changes that occur at birth?
Cessation of placental circulation and the lungs beginning to function.
What are angioblastic cords?
Paired endothelial strands in the cardiogenic mesoderm, the earliest signs of the heart.
How is blood oxygenated in fetal circulation?
In the placenta.
What is the purpose of the cardiovascular system in a fetus?
To provide for its prenatal needs.
What happens at the placenta in fetal circulation?
Fetal blood picks up oxygen and nutrients from maternal blood and eliminates carbon dioxide and wastes.
What is the remnant structure of the ductus venosus after birth?
Ligamentum venosum, a fibrous cord on the inferior surface of the liver.
What is the septum secundum?
A muscular fold that grows from the wall of the right atrium.
How does oxygenated blood flow before birth in relation to the foramen ovale (FO)?
Oxygenated blood from the inferior vena cava enters the right atrium, passes through the foramen ovale (FO), and enters the left atrium.
When is the ductus arteriosus 100% functionally closed?
By the end of 96 hours (4th day) of life.
Describe vasculogenesis.
Formation of new blood vessels from precursor cells, angioblasts.
What changes occur in neonatal circulation after birth?
Blood flow through the placenta ceases, the lungs begin to function, and the foramen ovale and ductus arteriosus close.
What is the embryological defect in Transposition of the Great Arteries?
The aorticopulmonary septum fails to pursue a spiral course during the division of the bulbus cordis and the truncus arteriosus.
What is the embryologic basis of Patent Ductus Arteriosus (PDA)?
Failure of the ductus arteriosus to involute, resulting from the failure of the wall of the ductus arteriosus to contract.
What is dextrocardia?
A congenital anomaly resulting from abnormal looping of the heart, where the heart bends to the left instead of to the right.
Describe the passage of oxygenated blood before birth.
Oxygenated blood from the inferior vena cava enters the right atrium, passes through the foramen ovale, and enters the left atrium.
When do blood vessels begin to develop in the embryo?
As early as the third week.
Describe angiogenesis.
Formation of channels through branching of pre-existing vessels.
What is the significance of heart looping during development?
Heart looping enables the tubular heart to resemble the structure of the adult heart.
What is the function of the ductus venosus in fetal circulation?
It allows highly oxygenated blood to bypass the liver and enter the inferior vena cava.
What are the two types of ridges formed during the partitioning of the bulbus cordis and truncus arteriosus?
Bulbar ridges from the bulbus cordis and truncal ridge from the truncus arteriosus.
What is the most common form of atrial septal defect (ASD)?
Patent foramen ovale.
What role do endocardial cushions play in heart development?
They contribute to the development of the heart valves and the membranous septum of the heart.
What happens to the foramen ovale (FO) at the 3rd month of life?
The foramen ovale (FO) fuses with the septum secundum (SS) to form the fossa ovales (oval fossa).
Why is the passage of blood in the opposite direction prevented before birth?
The valve of the foramen ovale (derived from septum primum) closes against the septum secundum.
What do angioblasts aggregate to form?
Blood islands.
What do angioblastic cords become after canalization?
Two heart tubes.
What is the cause of a ventricular septal defect (VSD)?
Failure in the development of the membranous part of the interventricular septum.
What is the state of the ductus arteriosus in fetal circulation?
Open.
What is the most common cause of cyanotic heart disease in newborns?
Transposition of the Great Arteries.
What structure is formed by the fusion of the bulbar and truncal ridges?
Aorticopulmonary septum (AS).
What is the most common type of congenital cardiac anomaly?
Ventricular septal defect (VSD).
What is the remnant structure of the ductus arteriosus after birth?
Ligamentum arteriosum.
Where is the muscular interventricular septum (MIS) located?
The muscular interventricular septum (MIS) is located at the floor of the ventricle.
What do angioblasts transform into during the development of blood vessels?
Endothelial cells.
What is the function of the foramen ovale (FO) before birth?
It allows oxygenated blood from the right atrium (RA) to enter the left atrium (LA).
Name the muscular bundles that form in the walls of the ventricles.
Trabeculae carneae, papillary muscles, and tendinous cords.
What embryological defect leads to dextrocardia?
Abnormal looping of the heart.
Describe the pathway of highly oxygenated blood from the placenta to the inferior vena cava.
Highly oxygenated blood from the placenta goes to the umbilical vein, approaches the liver, and then follows two pathways: half bypasses the liver via the ductus venosus to the IVC, and the other half enters the liver, passes through sinusoids, and then to the IVC via hepatic veins.
Describe the process of cardiac looping.
The heart bends ventrally and rotates to the right, positioning the atrium and sinus venosus dorsal to the bulbus cordis and ventricle.
What is the result of a left to right shunt of blood through a ventricular septal defect (VSD)?
It causes a left to right shunt of blood through the defect.
What do the intra-abdominal parts of the umbilical arteries become after birth?
Medial umbilical ligaments.
What is the remnant structure of the foramen ovale after birth?
Oval fossa, a crescent-shaped depression in the interatrial septum.
What causes the closure of the foramen ovale at birth?
Increased pulmonary blood flow and loss of flow from the umbilical vein, resulting in higher pressure in the left atrium than in the right atrium.
What triggers the constriction and closure of the ductus arteriosus in full-term newborns?
When the pO2 of blood in the ductus arteriosus reaches 50 mmHg.
What forms the lumen of blood vessels during development?
Cavities within blood islands.
What is patent ductus arteriosus (PDA)?
A congenital heart disease where the ductus arteriosus fails to close after birth.
What causes a patent ductus arteriosus (PDA)?
Failure of the ductus arteriosus to involute.
What is the function of the ductus arteriosus in fetal circulation?
It moves blood from the pulmonary artery to the aorta.
What does the aorticopulmonary septum (AS) divide the bulbus cordis and truncus arteriosus into?
Ascending aorta and pulmonary trunk.
What part of the interventricular septum is involved in the most common type of VSD?
The membranous part of the interventricular septum.
What characterizes a membranous ventricular septal defect?
Incomplete closure of the interventricular foramen due to the failure of the membranous part of the interventricular septum to develop.
What does the proximal part of the umbilical arteries become after birth?
Superior vesical artery, which supplies the urinary bladder.
What becomes of the septum primum?
It becomes the valve of the foramen ovale.
Describe the initial development of the heart.
The heart develops from a heart tube which eventually acquires dilations and constrictions to form the bulbus cordis, ventricle, atrium, and sinus venosus.
What causes the functional closure of the foramen ovale after birth?
The pressure in the left atrium (LA) becomes higher than that in the right atrium (RA).
What is the function of the foramen ovale in fetal circulation?
It moves blood from the right atrium to the left atrium, bypassing the lungs.
Why is cardiac looping essential?
It allows the straight heart to form a more complex structure resembling the adult heart.
What is the foramen primum?
An opening that allows passage of oxygenated blood from the right atrium to the left atrium.
Describe the initial growth of the septum primum (SP) in the partitioning of the primordial atrium.
The septum primum (SP) grows from the roof of the primordial atrium towards the endocardial cushions (EC), forming the foramen primum (FP) between the free edge of SP and EC.
What is the role of the septum secundum (SS) in the formation of the foramen ovale (FO)?
The septum secundum (SS) grows from the right atrium and overlaps/covers part of the foramen secundum (FS), forming the foramen ovale (FO).
What happens to the ductus arteriosus within the first 24-48 hours of life?
A small amount of blood passes through it.
Into what do angioblasts transform?
Endothelial cells.
What does the external layer of the developing heart become?
The primordial myocardium, which will become the muscular layer of the developing heart.
What forms the interventricular septum during the partitioning of the primordial ventricle?
A muscular part and a membranous part.
What are the two pathways of blood distribution from the right atrium in fetal circulation?
What is the transportation of the great arteries (TGA)?
A congenital heart disease where the positions of the pulmonary artery and the aorta are switched.
What is the pathway of fetal circulation?
The pathway includes the placenta, umbilical vein, ductus venosus, inferior vena cava, right atrium, foramen ovale, left atrium, left ventricle, aorta, and umbilical arteries.
What causes an atrial septal defect (ASD)?
Failure of the foramen ovale to close.
What is the state of the foramen ovale in neonatal circulation?
Closed.
What can a large ventricular septal defect cause?
It can cause blood to flow from the left to the right ventricles, then to the lungs, increasing pulmonary blood flow and leading to pulmonary hypertension.
What changes occur in the cardiovascular system at birth?
It undergoes changes to establish good neonatal circulation.
Describe the anatomical abnormality in Transposition of the Great Arteries.
The aorta lies anterior and to the right of the pulmonary trunk and arises from the right ventricle instead of the left.
