Embryology Flashcards
Timing of heart formation Teratogenic insults Atrial septal components Endocardial cushion D- and L-looping
The pacemaker of the heart is:
A. Bundle of His B. Purkinje fibers C. Atrioventricular node D. Sinoatrial node E. Coronary sinus
D. Sinoatrial node
Rhythmic beating and heart contractions originate in the sinoatrial node, which lies in the right atrium of the heart. The sinoartrial node is also known as the nodus sinuatrialis, sinuatrial node, sinus node, and cardiac pacemaker.
At what gestational age is a fetus most susceptible to teratogen exposure?
A. 0-4 weeks B. 4-8 weeks C. 12-16 weeks D. 20-24 weeks E. 30-36 weeks
B. 4-8 weeks
All major organ systems are formed between 4 and 8 weeks’ gestation. This time period is referred to as organogenesis. Any factors that interfere with development of the organ systems may cause faulty development.
The fourth aortic arch and common dorsal aorta becomes the:
A. Pulmonary arteries B. Ductal Arch C. Definitive Aorta D. Azygous vein E. Inferior Vena Cava
C. Definitive aorta
During fetal development, six pairs of arches arise from the trucus arteriosus. The forth arch has a left and a right branch. The left arch and common dorsal aorta become the feinitive aorta, while the right arch becomes part of the right subclavian artery.
Abnormal looping of the heart tube to the left will result in:
A. Complete transposition of the great arteries
B. Corrected transposition of the great arteries (1-ventricular loop)
C. Tetralogy of Fallot
D. Situs inversus totalis
E. Both A and B
B. Corrected transposition of the great arteries (1-ventricular loop)
Abnormal looping of the heart tube to the left instead of the right results in ventricular inversion, which is corrected transposition of the great arteries
At what point in heart development does the fetal heart begin to beat?
A. 7-10 days B. 12-14 days C. 21-28 days D. 28-35 days E. 35-48 days
C. 21-28 days
At approximately 28 days’ gestation, or by the end of the fourth week gestation, the contractions of the heart begin. This occurs in the ventriculobulbar portion of the heart.
In the sequence of fetal heart development, embryologically what is the last to form?
A. Bulboventricular looping B. Semilunar valves C. Atrioventicular valves D. Coronary sinus E. Paired heart tube
B. Semilunar valves
The development of the semilunar valves is completed by nine weeks’ gestation. These are the last structures to be completed in the development of the human heart. The folding of the heart is complete by day 28, the atrioventricular (AV) valves are complete by three months, and the coronary sinus is formed by 8 weeks.
A fully septated fetal heart is achieved by gestational week:
A. 4 B. 6 C. 8 D. 10 E. 12
C. 8
Four separate pulmonary veins are formed when the left and right pulmonary veins are absorbed. The four pulmonary veins then normally enter into the:
A. Coronary sinus B. Right atrium C. Left atrium D. Right ventricle E. Left ventricle
C. Left atrium
Initially, there is a common pulmonary vein and a right and left pulmonary vein. All of these veins are absorbed, resulting in four pulmonary veins that enter into the left atrium. They are right upper, right lower, left upper, and left lower pulmonary veins.
Endocardial cushions are involved in the development of the:
A. Semilunar valves B. Atrioventricular valves C. Membranous septum D. Both A and B E. All of the above
E. All of the above
(Semilunar valves, Atrioventricular valves, Membranous septum)
The endocardial cushions are developed from the extracellular matrix. They are involved in the formation of the semilunar valves, atrioventricular valves, and membranous septum. Endocardial cushion abnormalities commonly result in atrioventricular valve canal defects. (See also the explanation for answer 31.)
What syndrome is thought to be a result of a midline development field defect?
A. Polysplenia syndrome B. Asplenia syndrome C. Ivemark syndrome D. Right atrial isomerism E. All of the above
E. All of the above
(Polysplenia syndrome, Asplenia syndrome, Ivemark syndrome, Right atrial isomerism)
Asplenia and polyspenia syndromes are abnormalities caused by a midline development field defect. This defect results in complex malformations of the abdominal and cardiovascular systems. Symmetry of these organ systems is affected. Ivemark syndrome and right atrial isomerism are both alternate terms for asplenia.
The period of organogenesis occurs between which weeks of gestation?
A. 0-3 B. 3-6 C. 4-8 D. 8-10 E. 10-12
C. 4-8
All major organ systems are formed between 4 and 8 weeks’ gestation. This time period is referred to as organogenesis. Any factors that interfere with development of these organ systems may cause faulty development.
The partitioning of the embryonic fetal heart into the chambers of the atria and ventricles begins at approximately what gestational day?
A. Unknown B. 16 C. 18 D. 22 E. 28
E. 28
If the primitive heart tube loops to the right instead of the left, the result would be:
A. Normal great artery relationship (d-ventricular loop)
B. Ventricular inversion
C. Corrected transposition of the great arteries (l-ventricular loop)
D. Situs inversus
E. Bilateral right-sidedness
A. Normal great artery relationship (d-ventricular loop)
In normal fetal heart development, the heart tube bends to the right, resulting in a normal relationship of the great arteries.
Coarctation of the aorta is thought to be the result of:
A. Aberrant ductal tissue
B. Decreased blood flow through the aortic isthmus
C. Failure of the fourth and sixth aortic arch to connect with the descending aorta
E. All of the above
E. All of the above
(Aberrant ductal tissue, Decreased blood flow through the aortic isthmus, Failure of the fourth and sixth aortic arch to connect with the descending aorta)
