Cardiovascular System

MULTIPLE CHOICE

Directions: Each group of questions below consists of a numbered list of descriptive words or phrases accompanied by a diagram with certain parts indicated by letters or by a list of lettered headings. For each numbered word or phrase, select the lettered part or heading that matches it correctly, and then insert the letter in the space to the right of the appropriate number. Sometimes more than one numbered word or phrase may be correctly matched to the same lettered part or heading.

        1.  

________ Directs blood into the left atrium

a.
A
b.
B
c.
C
d.
D
e.
E

ANS:   C

Blood from the inferior vena cava (IVC) is directed by the inferior border of the septum secundum (crista dividens) through the oval foramen into the left atrium.

        2.  

________ Carry relatively little fetal blood

a.
A
b.
B
c.
C
d.
D
e.
E

ANS:   D

The pulmonary veins carry relatively little blood to the left atrium before birth because the lungs are not functioning. When the lungs expand at birth and the pulmonary vascular resistance falls, there is a marked increase in pulmonary blood flow with a consequent increased flow of oxygenated blood to the left atrium through the pulmonary veins.

        3.  

________ Remains of the septum primum

a.
A
b.
B
c.
C
d.
D
e.
E

ANS:   E

The remains of the septum primum are represented in the drawing by the valve of the oval foramen. This valve is forced open by blood from the IVC that is directed through the oval foramen by the crista dividens (inferior edge of septum secundum). The oval foramen normally closes at birth when pressure in the left atrium rises above that in the right atrium.

        4.  

________ Opening in the septum secundum

a.
A
b.
B
c.
C
d.
D
e.
E

ANS:   B

The oval foramen is a normal opening in the septum secundum. It permits well-oxygenated blood from the placenta that comes from the IVC to enter the left atrium. If the oval foramen fails to close at birth, a cardiac anomaly known as secundum-type ASD exists. This common congenital heart defect accounts for about 8% of cases of congenital heart disease.

        5.  

________ Carries well-oxygenated blood

a.
A
b.
B
c.
C
d.
D
e.
E

ANS:   A

The IVC carries well-oxygenated blood from the placenta. This fetal blood returns from the placenta in the umbilical vein. About half the blood passes through the hepatic sinusoids before entering the IVC. The other half is shunted by way of the ductus venosus directly from the umbilical vein to the IVC.

        6.  

________ Septum secundum

a.
A
b.
B
c.
C
d.
D
e.
E

ANS:   C

The septum secundum is the second part of the interatrial septum to form. The crista dividens, its inferior border, is indicated by the pointer. It directs most of the blood from the IVC through the opening in the septum secundum (oval foramen) into the left atrium. The smaller portion of blood, turned back by the septum secundum, enters the right ventricle.

        7.   ________ Round ligament of the liver

a.
Ductus arteriosus
b.
Septum primum
c.
Sixth pharyngeal arch artery
d.
Sinus venosus
e.
Umbilical vein

ANS:   E

The intra-abdominal part of the fetal umbilical vein becomes the adult round ligament of the liver (L. ligamentum teres hepatis). It passes from the umbilicus to the porta hepatis, where it attaches to the left branch of the portal vein.

        8.   ________ Carries poorly oxygenated blood into the right atrium

a.
Ductus arteriosus
b.
Septum primum
c.
Sixth pharyngeal arch artery
d.
Sinus venosus
e.
Umbilical vein

ANS:   D

The sinus venosus initially is a separate chamber of the heart that opens into the caudal wall of the right atrium. The right horn of the sinus venosus becomes incorporated into the wall of the right atrium and forms its smooth-walled part called the sinus venarum. The left horn of the sinus venosus becomes the coronary sinus.

        9.   ________ Arterial shunt

a.
Ductus arteriosus
b.
Septum primum
c.
Sixth pharyngeal arch artery
d.
Sinus venosus
e.
Umbilical vein

ANS:   A

The ductus arteriosus is an arterial shunt that carries blood from the left pulmonary artery to the arch of the aorta before birth. Because the lungs are not functioning, most of the blood in the pulmonary trunk bypasses the lungs and enters the descending aorta.

      10.   ________ Floor of the oval fossa

a.
Ductus arteriosus
b.
Septum primum
c.
Sixth pharyngeal arch artery
d.
Sinus venosus
e.
Umbilical vein

ANS:   B

The floor of the oval fossa in the interatrial septum is formed by tissue derived from the septum primum (valve of oval foramen). When the pressure in the left atrium rises at birth, the valve of the oval foramen closes and later fuses with the septum secundum. This valvular tissue forms the floor of the oval fossa.

      11.   ________ Ductus venosus

a.
Ductus arteriosus
b.
Septum primum
c.
Sixth pharyngeal arch artery
d.
Sinus venosus
e.
Umbilical vein

ANS:   E

About half the blood coming from the placenta in the umbilical vein is shunted through the liver by way of the ductus venosus into the IVC. The remainder of the blood enters the liver and is carried to the IVC by the hepatic veins.

      12.   ________ Right recurrent laryngeal nerve

a.
Ductus arteriosus
b.
Septum primum
c.
Sixth pharyngeal arch artery
d.
Sinus venosus
e.
Umbilical vein

ANS:   C

The recurrent laryngeal nerves hook around the sixth pair of aortic arch arteries. On the right, the distal part of the sixth arch artery and the fifth aortic arch artery degenerate, leaving the right recurrent laryngeal nerve hooked around the right subclavian artery. On the left, the recurrent laryngeal nerve hooks around the ductus arteriosus (ligamentum arteriosum in the adult) and the arch of the aorta.

      13.  

________ Derivative of an intersegmental artery

a.
A
b.
B
c.
C
d.
D
e.
E

ANS:   C

The left subclavian artery, unlike the right subclavian artery, is not derived from an aortic arch artery or the dorsal aorta. It develops from the seventh intersegmental artery that arises from the descending aorta and moves cranially as the arch of the aorta forms.

      14.  

________ Forms from the sixth pharyngeal arch artery

a.
A
b.
B
c.
C
d.
D
e.
E

ANS:   D

The ductus arteriosus develops from the distal portion of the left sixth aortic arch artery. It passes from the left pulmonary artery to the aorta and, before birth, carries most of the blood from the pulmonary trunk into the aorta. The lungs are not functioning and so require little blood. The ductus arteriosus usually constricts slightly after birth and closes anatomically during the first 3 months.

      15.  

________ Derived from the truncus arteriosus

a.
A
b.
B
c.
C
d.
D
e.
E

ANS:   A

The proximal part of the ascending aorta is derived from the truncus arteriosus when it is divided by the aorticopulmonary septum. The remainder of the ascending aorta develops from the aortic sac.

      16.  

________ Formed by fusion of the dorsal aortae

a.
A
b.
B
c.
C
d.
D
e.
E

ANS:   E

The descending aorta forms when the paired dorsal aortae of the embryo fuse. The cranial part of the right dorsal aorta normally involutes, but if it persists, a double aortic arch forms that may compress the trachea and esophagus.

      17.  

________ Derived from the third aortic pharyngeal arch artery

a.
A
b.
B
c.
C
d.
D
e.
E

ANS:   B

The right common carotid artery is derived from the proximal part of the right third aortic arch artery. This artery also gives rise to the internal carotid artery on this side.

      18.  

________ Becomes ligamentous during infancy

a.
A
b.
B
c.
C
d.
D
e.
E

ANS:   D

The ductus arteriosus constricts at birth but usually is patent for a week or so. Proliferation of endothelial and fibrous tissues of the ductus arteriosus usually results in its anatomic closure by the end of the third month.

      19.   ________ Pulmonary valve stenosis

a.
Ductus arteriosus
b.
Septum primum
c.
Sixth pharyngeal arch artery
d.
Sinus venosus
e.
Umbilical vein

ANS:   E

Stenosis of the pulmonary tract is one of the four anomalies of the heart and great vessels included in the tetralogy of Fallot. These defects are regarded as the most important of the cardiac defects that produce cyanosis.

      20.   ________ Rubella syndrome

a.
Ductus arteriosus
b.
Septum primum
c.
Sixth pharyngeal arch artery
d.
Sinus venosus
e.
Umbilical vein

ANS:   C

Patent ductus arteriosus is the most common congenital anomaly of the heart and great vessels associated with maternal rubella infection during the first trimester.

      21.   ________ Right ventricular hypertrophy

a.
Ductus arteriosus
b.
Septum primum
c.
Sixth pharyngeal arch artery
d.
Sinus venosus
e.
Umbilical vein

ANS:   B

Enlargement and hypertrophy of the right ventricle result from high blood pressure, often resulting from pulmonary stenosis. The narrowing may occur at the infundibulum of the right ventricle, the pulmonary valve, or, less commonly, in the pulmonary trunk. E is also correct, but B is the better answer.

      22.   ________ Most common cardiac defect

a.
Ductus arteriosus
b.
Septum primum
c.
Sixth pharyngeal arch artery
d.
Sinus venosus
e.
Umbilical vein

ANS:   D

VSD is the most common cardiac defect. It may occur with various other cardiac defects (e.g., in tetralogy of Fallot). VSD most commonly consists of an opening (1 to 15mm in diameter) in the membranous part of the interventricular septum.

      23.   ________ Constriction of aorta

a.
Ductus arteriosus
b.
Septum primum
c.
Sixth pharyngeal arch artery
d.
Sinus venosus
e.
Umbilical vein

ANS:   A

In preductal coarctation, the aorta constricts superior to the ductus arteriosus, which usually is patent. More often, the constriction is inferior to the ductus (postductal coarctation).

      24.   ________ Overriding aorta

a.
Ductus arteriosus
b.
Septum primum
c.
Sixth pharyngeal arch artery
d.
Sinus venosus
e.
Umbilical vein

ANS:   E

Overriding aorta or an aorta arising directly over a VSD, and thus overriding both ventricular cavities, is an essential feature of the tetralogy of Fallot. People with this group of cardiac defects are cyanotic because not enough blood flows to the lungs for oxygenation. As long as the ductus arteriosus remains patent, there is compensatory flow through it from the aorta to the pulmonary arteries. If the ductus closes, as commonly occurs, the deficit in pulmonary circulation increases.

      25.  

________ A cardiac defect in the area of the oval fossa

a.
A
b.
B
c.
C
d.
D
e.
E

ANS:   B

Atrial septal defect (ASD) is a common congenital anomaly. It occurs more frequently in females than in males. A patent oval foramen is the most common form of ASD, resulting from incomplete fusion between the septum secundum and the flap-type valve of the oval foramen. Before birth, most of the blood entering the right atrium is shunted through the oval foramen into the left atrium. After birth, the pressure in the left atrium rises with the return of blood from the lungs. As a result, the septum primum becomes pressed against the septum secundum, and eventually the oval foramen is permanently closed. Of the main types of ASD, the secundum ASD is most common and is located in the area of the oval fossa.

      26.  

________ Normally communicates with the right ventricle

a.
A
b.
B
c.
C
d.
D
e.
E

ANS:   D

The pulmonary trunk normally communicates with the right ventricle, transporting poorly oxygenated blood to the lungs after birth. In typical cases of transposition of the great arteries, the aorta arises from the right ventricle anteriorly, and on the left the pulmonary artery arises from the left ventricle posteriorly. Transposition of the great arteries is the most common cause of cyanotic heart disease in newborn infants, and it is often found in association with other cardiac anomalies.

      27.  

________ Closes by the end of the seventh embryonic week

a.
A
b.
B
c.
C
d.
D
e.
E

ANS:   E

A crescentic interventricular foramen, between the free edge of the muscular part of the interventricular septum and the fused endocardial cushions, permits blood to pass between the right and left ventricles until the seventh week. With the formation of the membranous part of the interventricular septum by the end of the seventh week, the interventricular foramen is obliterated. The membranous part of the interventricular septum, derived from the fused endocardial cushions, merges with the bulbar ridges of the aorticopulmonary septum and the muscular part of the interventricular septum.

      28.  

________ Is formed from the dorsal aorta

a.
A
b.
B
c.
C
d.
D
e.
E

ANS:   C

The distal part of the arch of the aorta is derived from the left dorsal aorta; its proximal part is formed from the fourth aortic arch and the aortic sac. In this case of transposition of the great arteries, the aorta is shown arising from the right ventricle. Coarctation of the aorta almost invariably is located where the ductus arteriosus connects with the aortic arch and the descending aorta.

      29.  

________ Is partly derived from the sinus venosus

a.
A
b.
B
c.
C
d.
D
e.
E

ANS:   A

The formation and subsequent fusion of the septum primum and septum secundum divide the primordial atrium into a right atrium and a left atrium. Initially, the sinus venosus opens into the dorsal wall of the primordial right atrium. By the end of the fourth week, the right horn of the sinus venosus is larger than the left. The right horn of the sinus venosus becomes incorporated into the wall of the right atrium, and the left horn forms the coronary sinus. The smooth part of the wall of the right atrium is known as the sinus venarum because it is derived from the sinus venosus.