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What is the correct order of heart development?
What is the correct order of heart development?
What happens to the heart tube as it grows?
What happens to the heart tube as it grows?
What is the function of the sinus venosus?
What is the function of the sinus venosus?
What is the relationship between the bulboventricular loop and the cephalic portion?
What is the relationship between the bulboventricular loop and the cephalic portion?
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What happens to the atrium during heart development?
What happens to the atrium during heart development?
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What is the fate of the proximal part of the bulbus?
What is the fate of the proximal part of the bulbus?
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What are the two terms used somewhat confusingly for the parts at the arterial end?
What are the two terms used somewhat confusingly for the parts at the arterial end?
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What is the connection between the truncus arteriosus and the conus arteriosus?
What is the connection between the truncus arteriosus and the conus arteriosus?
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Which blood vessel carries oxygen-rich blood to the fetus?
Which blood vessel carries oxygen-rich blood to the fetus?
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What structure directs most of the blood from the IVC into the left atrium?
What structure directs most of the blood from the IVC into the left atrium?
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What is the primary function of the fetal lungs?
What is the primary function of the fetal lungs?
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Which part of the heart receives blood from the superior vena cava (SVC)?
Which part of the heart receives blood from the superior vena cava (SVC)?
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What happens to the blood that does not pass through the foramen ovale in the fetal heart?
What happens to the blood that does not pass through the foramen ovale in the fetal heart?
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What is the oxygen content of the blood that leaves the right ventricle through the pulmonary trunk?
What is the oxygen content of the blood that leaves the right ventricle through the pulmonary trunk?
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What is the main difference between the blood in the IVC and the blood in the umbilical vein?
What is the main difference between the blood in the IVC and the blood in the umbilical vein?
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What is the primary effect of Tetralogy of Fallot?
What is the primary effect of Tetralogy of Fallot?
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Which of the following receives well-oxygenated blood from the umbilical vein?
Which of the following receives well-oxygenated blood from the umbilical vein?
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Which of the following is a characteristic of Persistent Truncus Arteriosus?
Which of the following is a characteristic of Persistent Truncus Arteriosus?
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What is the origin of the aorta in Transposition of Great Vessels?
What is the origin of the aorta in Transposition of Great Vessels?
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What is the resulting effect of Tetralogy of Fallot on pulmonary flow?
What is the resulting effect of Tetralogy of Fallot on pulmonary flow?
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What is the characteristic of cyanotic heart defects?
What is the characteristic of cyanotic heart defects?
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What is the percentage of all CHDs that Tetralogy of Fallot accounts for?
What is the percentage of all CHDs that Tetralogy of Fallot accounts for?
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What is the defect accompanied by in Persistent Truncus Arteriosus?
What is the defect accompanied by in Persistent Truncus Arteriosus?
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What is the characteristic of Transposition of Great Vessels?
What is the characteristic of Transposition of Great Vessels?
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What is the primary reason for the thinning of the pulmonary artery walls during the first few breaths?
What is the primary reason for the thinning of the pulmonary artery walls during the first few breaths?
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What causes the pressure in the left atrium to be higher than in the right atrium after birth?
What causes the pressure in the left atrium to be higher than in the right atrium after birth?
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What is the main reason for the reversal of blood flow in the ductus arteriosus (DA) after birth?
What is the main reason for the reversal of blood flow in the ductus arteriosus (DA) after birth?
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How does the increased workload of the left ventricle after birth affect the ventricular walls?
How does the increased workload of the left ventricle after birth affect the ventricular walls?
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What is the usual timeframe for the functional closure of the ductus arteriosus in a normal full-term infant?
What is the usual timeframe for the functional closure of the ductus arteriosus in a normal full-term infant?
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Which of the following conditions can cause the ductus arteriosus to remain open longer?
Which of the following conditions can cause the ductus arteriosus to remain open longer?
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What is the primary function of the ductus arteriosus in a fetus?
What is the primary function of the ductus arteriosus in a fetus?
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Which of these structures is NOT directly involved in the transition of fetal circulation to neonatal circulation?
Which of these structures is NOT directly involved in the transition of fetal circulation to neonatal circulation?
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What is the primary function of the ductus venosus in fetal circulation?
What is the primary function of the ductus venosus in fetal circulation?
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Which vascular structures are critical during the transitional circulation at birth?
Which vascular structures are critical during the transitional circulation at birth?
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What happens to blood flow in the ductus venosus when the sphincter contracts?
What happens to blood flow in the ductus venosus when the sphincter contracts?
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What characterizes the state of pulmonary vessels prenatally?
What characterizes the state of pulmonary vessels prenatally?
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What is the effect of uterine contractions on blood flow in the umbilical vein?
What is the effect of uterine contractions on blood flow in the umbilical vein?
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How does typical blood flow from the placenta reach the heart in fetal circulation?
How does typical blood flow from the placenta reach the heart in fetal circulation?
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What type of blood is primarily delivered to the fetus from the placenta?
What type of blood is primarily delivered to the fetus from the placenta?
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What is the role of the foramen ovale in fetal circulation?
What is the role of the foramen ovale in fetal circulation?
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Study Notes
Formation of the Heart Loop
- Heart tube components include bulbus cordis, ventricle, atrium, truncus arteriosus, conus arteriosus, and sinus venosus.
- As the heart tube grows, it bends to fit within the pericardial cavity; primitive heart chambers become recognizable.
- Sinus venosus receives blood from body veins; blood flow continues from the ventricle into the bulbus cordis and then to the arteries.
Bending of the Heart Tube
- Bulboventricular portion forms a loop with a cephalic portion that bends ventrally, caudally, and slightly to the right.
- The atrium bulges laterally from the bulbus, moving dorsocranially.
Fetal Blood Flow Dynamics
- Fetal lungs do not provide gas exchange; key structures in transitional circulation include ductus venosus, foramen ovale, and ductus arteriosus.
- Highly oxygenated blood from placenta enters the fetus via the umbilical vein under high pressure.
Ductus Venosus Functionality
- Ductus venosus connects umbilical vein to inferior vena cava (IVC), allowing half the blood to bypass the liver.
- Blood flow through the ductus venosus is regulated by a sphincter mechanism, diverting blood based on pressure changes.
Entry and Mixing of Blood
- Blood in the IVC mixes poorly oxygenated blood from the lower body with well-oxygenated blood from the placenta before entering the right atrium.
- Most blood from IVC is channeled through the crista dividens into the left atrium, mixing with smaller amounts of poorly oxygenated blood returning from lungs.
Postnatal Circulation Changes
- At birth, increased pulmonary blood flow leads to higher pressure in the left atrium, functionally closing the foramen ovale.
- Blood from the right ventricle flows into the pulmonary trunk; pulmonary vascular resistance drops compared to systemic vascular resistance.
Right and Left Ventricular Development
- In fetuses, right ventricular wall is thicker due to increased workload; after birth, left ventricular wall becomes thicker as it takes on more responsibility.
- Ductus arteriosus may constrict postnatally, often closing completely within 96 hours in healthy infants.
Congenital Heart Defects
- Tetralogy of Fallot includes pulmonary stenosis, ventricular septal defect, overriding aorta, and right ventricular hypertrophy; results in cyanosis.
- Persistent truncus arteriosus occurs when truncoconal ridges fail to fuse, causing cyanosis and increased blood flow to the lungs.
- Transposition of great vessels arises from abnormal descending of truncoconal septum, leading to aorta originating from right ventricle.
Implications of Fetal Circulation
- Fetal circulation relies on overlaying structures allowing for bypassing of lungs; post-birth adaptations are crucial for normal gas exchange transition.
- Morphological changes and vascular resistance alterations are key factors for the heart's functional shift from prenatal to neonatal life.
Additional Heart Defects
- Persistence of ductus arteriosus in preterm infants; closure rates vary significantly between full-term and preterm infants.
- Circulatory anomalies can compromise oxygenation and normal function, necessitating careful monitoring and intervention when necessary.
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Description
Quiz on the formation of heart loop, covering stages of heart tube development from bulbus cordis to sinus venosus.