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Questions and Answers
What is the outermost layer of the cardiac tube called?
What is the outermost layer of the cardiac tube called?
The sinus venosus is responsible for the outflow of blood from the primitive heart.
The sinus venosus is responsible for the outflow of blood from the primitive heart.
False
What are the three layers of the cardiac tube?
What are the three layers of the cardiac tube?
Epicardium, Myocardium, Endocardium
The primitive ventricle develops into the apical portion of the ______ and inlet portion of the ______.
The primitive ventricle develops into the apical portion of the ______ and inlet portion of the ______.
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Match the parts of the cardiac tube with their corresponding developed structures:
Match the parts of the cardiac tube with their corresponding developed structures:
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Which of the following arches persist in the adult heart?
Which of the following arches persist in the adult heart?
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The truncus arteriosus is formed from the septum primum.
The truncus arteriosus is formed from the septum primum.
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What structures do arches three, four, and six develop into in the adult heart?
What structures do arches three, four, and six develop into in the adult heart?
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What do the umbilical veins carry?
What do the umbilical veins carry?
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The left horn of the sinus venosus forms the coronary sinus.
The left horn of the sinus venosus forms the coronary sinus.
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The _________ is a venous channel that receives blood from the coronary veins and empties into the right atrium.
The _________ is a venous channel that receives blood from the coronary veins and empties into the right atrium.
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Match the parts of the heart with their functions:
Match the parts of the heart with their functions:
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What is formed when the heart tubes are completely fused?
What is formed when the heart tubes are completely fused?
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The aortic arch system consists of ______ arches in the fetus.
The aortic arch system consists of ______ arches in the fetus.
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Match the following components with their functions or characteristics:
Match the following components with their functions or characteristics:
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What is the role of the inferior vena cava (IVC) in the circulatory system?
What is the role of the inferior vena cava (IVC) in the circulatory system?
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The right ventricle (RV) pumps blood directly to the aorta.
The right ventricle (RV) pumps blood directly to the aorta.
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What happens to the blood in the lungs?
What happens to the blood in the lungs?
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The blood returning to the heart from the lower body is deoxygenated because it has already delivered _____ to the tissues.
The blood returning to the heart from the lower body is deoxygenated because it has already delivered _____ to the tissues.
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Match the following components of the heart's circulation with their respective function:
Match the following components of the heart's circulation with their respective function:
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What is the main purpose of the fetal shunts like Foramen Ovale and Ductus Arteriosus?
What is the main purpose of the fetal shunts like Foramen Ovale and Ductus Arteriosus?
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The Foramen Ovale closes after birth, leaving behind a structure known as the fossa ovalis.
The Foramen Ovale closes after birth, leaving behind a structure known as the fossa ovalis.
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What two main structures does the Ductus Arteriosus connect?
What two main structures does the Ductus Arteriosus connect?
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The _____ arteries develop from the truncus arteriosus.
The _____ arteries develop from the truncus arteriosus.
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Match the fetal shunts to their adult remnants:
Match the fetal shunts to their adult remnants:
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During fetal circulation, where do oxygenated blood and nutrients primarily originate from?
During fetal circulation, where do oxygenated blood and nutrients primarily originate from?
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What is the role of the bulbar ridges in the heart development?
What is the role of the bulbar ridges in the heart development?
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The Ductus Venosus is an adult remnant of a fetal shunt that connects the right and left atria.
The Ductus Venosus is an adult remnant of a fetal shunt that connects the right and left atria.
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What happens to blood flow when the umbilical cord is clamped at birth?
What happens to blood flow when the umbilical cord is clamped at birth?
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After birth, the ductus arteriosus closes immediately due to muscular contraction.
After birth, the ductus arteriosus closes immediately due to muscular contraction.
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What structure allows oxygenated blood from the placenta to enter the fetus?
What structure allows oxygenated blood from the placenta to enter the fetus?
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After birth, increased blood returning to the left atrium causes the _____ to close.
After birth, increased blood returning to the left atrium causes the _____ to close.
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Match the following blood flow pathways with their descriptions:
Match the following blood flow pathways with their descriptions:
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Which of the following occurs to pulmonary pressure after birth?
Which of the following occurs to pulmonary pressure after birth?
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What happens to deoxygenated blood after it enters the right atrium during fetal circulation?
What happens to deoxygenated blood after it enters the right atrium during fetal circulation?
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The majority of enriched blood in the right atrium flows directly to the right ventricle.
The majority of enriched blood in the right atrium flows directly to the right ventricle.
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Study Notes
Cardiac Embryology & Fetal Circulation
- The heart is the first organ to function in an embryo
- The heart develops from a pair of heart tubes
- These tubes consist of three layers: epicardium, myocardium, and endocardium
- The epicardium forms the outermost layer and boundary of the pericardial cavity
- The myocardium is the next inner layer, forming the myoepicardium with the epicardium
- Cardiac jelly fills the space between the myocardium and endocardium
- Endocardial cells line the lumen of the cardiac tube
Week 3
- Heart tubes fuse to form a single endocardial heart tube
- The tube has specific parts: aortic sac, truncus arteriosus, bulbus cordis, interventricular sulcus, primitive ventricle, atrioventricular sulcus, primitive atrium, sinus venosus
Week 3-5 Development
- Sinus venosus, primitive atrium, and primitive ventricle develop components of the heart's chambers
- The atrioventricular sulcus divides the primitive atrium and primitive ventricle
- The primitive ventricle develops into the left and right ventricles
- The bulbus cordis becomes the outflow tracts for the aorta and pulmonary trunk
- The aortic sac becomes part of the aorta
- The interventricular sulcus forms between the ventricles
Weeks 4-7 Development
- The heart loops dextro(right) to create the S-shaped configuration, forcing the tube to fold
- The bulboventricular loop forms
- The bulbus cordis gives rise to the right ventricle and part of the outflow tracts
- The primitive ventricle gives rise to the left ventricle
- The primitive atrium gives rise to the atria.
- The sinus venosus is incorporated into the right atrium
- The six aortic arches develop from the aortic sac, with only 3, 4, and 6 persisting in the adult heart
- Number 3 becomes the carotid arteries
- Number 4 becomes the aortic arch
- Number 6 becomes the pulmonary arteries and ductus arteriosus
- The septum primum grows downward to form a septum between the atria
- The ostium primum is the opening that remains in the septum primum
- The septum secundum forms parallel to septum primum
- The endocardial cushions form within the atrioventricular canal.
- The ventricular septum develops
- Only one truncus arteriosus remains. This becomes the aorta and pulmonary trunk
Week 6-7 Development
- The septum secundum fully fuses to the septum primum, creating the foramen ovale.
- The superior and inferior endocardial cushions fuse
- The atrioventricular valve cusps form
- The formation of the coronary sinus
Fetal Shunts
- Foramen ovale - blood bypasses the lungs by moving from the right atrium to left atrium
- Ductus arteriosus - blood shunts from the pulmonary artery to the aorta
- Ductus venosus - blood bypasses the liver by moving from umbilical vein to inferior vena cava
After Birth
- The foramen ovale and ductus arteriosus close due to higher pressure on the Left Atrium side and pulmonary blood flow
- The umbilical vein becomes the ligamentum teres, and the ductus venosus becomes the ligamentum venosum
- The umbilical arteries close, and the umbilical cord is no longer necessary
- Pulmonary pressures decrease with increased blood flow and oxygen intake in the lungs
- The closure of the ductus arteriosus and foramen ovale completes the transition from fetal circulation to newborn circulation
Failure of Shunts Closing
- If fetal shunts fail to close after birth, they are termed patent
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Description
This quiz covers the essential aspects of cardiac embryology and fetal circulation, focusing on the development of the heart from a pair of heart tubes. It highlights key structures like the endocardial heart tube and the components of heart chambers that emerge between weeks 3 to 5. Test your understanding of how these critical anatomical features form and function in a developing embryo.
