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Question 1

A fetus has improper development of the bulbus cordis. Which structures will have defects as a result?

Answer 1

The smooth parts (outflow tract) of the left and right ventricles

Question 2

A fetus has improper development of the truncus arteriosus. Which structures will have defects as a result?

Answer 2

The ascending aorta and the pulmonary trunk

Question 3

A fetus has improper development of the primitive atrium. Which structures will have defects as a result?

Answer 3

The trabeculated part of the left and right atria

Question 4

A fetus has improper development of the primitive ventricle. Which structures will have defects as a result?

Answer 4

The trabeculated part of the left and right ventricles

Question 5

A fetus has improper development of the primitive pulmonary vein. Which structure will have defects as a result?

Answer 5

The smooth part of the left atrium

Question 6

A fetus has improper development of the left horn of the sinus venosus. Which structure will have defects as a result?

Answer 6

The coronary sinus

Question 7

A fetus has improper development of the right horn of the sinus venosus. Which structure will have defects as a result?

Answer 7

The smooth part of the right atrium (sinus venarum)

Question 8

A fetus has improper development of the right common cardinal/right anterior cardinal veins. Which structure will have defects as a result?

Answer 8

The superior vena cava

Question 9

What is the first functional organ in human embryos? When does this organ start to function?

Answer 9

The heart; spontaneous beats are seen by 4 weeks of development

Question 10

Which two cardiac structures are ultimately created by neural crest and endocardial cell migrations?

Answer 10

The ascending aorta and pulmonary trunk, which are created from the truncus arteriosus

Question 11

A patient has dextrocardia and chronic sinusitis. What caused the situs inversus observed here (see image)?

Answer 11

Kartagener syndrome (primary ciliary dyskinesia) causing a defect in left-right dynein leads to aberrant cardiac looping

Question 12

A patient has failure of neural crest cell migration during embryonic heart development. Name three conditions she might have.

Answer 12

Transposition of great vessels, tetralogy of Fallot, and persistent truncus arteriosus

Question 13

A woman is seen at 6 weeks’ gestation. What might she be told about the development of her fetus’ heart?

Answer 13

Cardiac looping has begun with establishment of left-right polarity, and there have been spontaneous heart beats since 4 weeks

Question 14

What is the opening in the early muscular ventricular septum called?

Answer 14

Interventricular foramen

Question 15

During the first step of septation of the chambers, what structure grows? What structure narrows as a result?

Answer 15

The septum primum grows toward the endocardial cushions; the foramen primum narrows

Question 16

The ____ divides the truncus arteriosus into the aortic and pulmonary trunks.

Answer 16

Aorticopulmonary septum

Question 17

During the second step of septation of the chambers, what foramen develops? What foramen disappears as a result?

Answer 17

The foramen secundum forms in the septum primum; the foramen primum disappears

Question 18

The aorticopulmonary septum rotates and fuses with the muscular ventricular septum to form the ____.

Answer 18

Membranous interventricular septum

Question 19

During the third step of septation of the chambers, what structure develops? What foramen becomes is essential to the embryo’s hemodynamics?

Answer 19

The septum secundum develops; the foramen secundum maintains a right-to-left shunt

Question 20

The ____ forms to close the interventricular foramen and separate the two ventricles.

Answer 20

Membranous interventricular septum

Question 21

During the fourth step of septation of the chambers, what structure expands? What foramen persists and contributes to the fetal circulation?

Answer 21

The septum secundum expands and covers most of the foramen secundum; the residual foramen is the foramen ovale

Question 22

A newborn has failure of the aorticopulmonary septum and muscular ventricular septum to fuse. What condition is this?

Answer 22

Ventricular septal defect (most commonly occurs in the membranous septum)

Question 23

During the fifth step of septation of the chambers, what structure is altered to become an important part of the fetal circulation?

Answer 23

The remaining portion of the septum primum forms the valve of the foramen ovale

Question 24

Which two heart valves are derived from the endocardial cushions of the outflow tract?

Answer 24

Aortic and pulmonic

Question 25

During the sixth step of septation of the chambers, what two structures fuse? What structure does this result in the formation of?

Answer 25

The septum secundum and septum primum fuse; forms the atrial septum

Question 26

Which two heart valves are derived from fused endocardial cushions of the AV canal?

Answer 26

Mitral and tricuspid

Question 27

During the seventh and final step of septation of the chambers, what structure closes off? When does this event take place?

Answer 27

The foramen ovale usually closes soon after birth because of increased left atrial pressure

Question 28

A patient with an Ebstein anomaly has a ____ (stenotic/displaced/atretic/regurgitant) valve anomaly.

Answer 28

Displaced

Question 29

• A newborn has failure of the endocardial cushions in the AV canal to properly form valves. This may lead to which valvular anomalies?

Answer 29

Mitral and/or tricuspid atresia

Question 30

You observe a paradox embolus in a patient causing a stroke. Which heart structure is likely defective in this patient?

Answer 30

The atrial septum is likely defective, allowing venous emboli to enter systemic arterial circulation (patent foramen ovale can cause this)

Question 31

You see an unfused opening between the septa primum/secundum in a man. This opening normally closes from more pressure in what heart chamber?

Answer 31

The unfused opening is a patent foramen ovale, which usually closes (after birth) from increased left atrial pressure

Question 32

A patient is incidentally found to have a patent foramen ovale on echocardiogram. Is it necessary to call cardiac surgery right away?

Answer 32

No, as the majority of patent foramen ovales do not require treatment and are left untreated

Question 33

During fetal erythropoiesis, when does the yolk sac produce fetal red blood cells?

Answer 33

Weeks 3–8

Question 34

During fetal erythropoiesis, when does the liver produce fetal red blood cells?

Answer 34

Week 6 to birth

Question 35

During fetal erythropoiesis, when does the spleen produce fetal red blood cells?

Answer 35

Weeks 10–28

Question 36

During fetal erythropoiesis, when does the bone marrow start producing fetal red blood cells?

Answer 36

Week 18 to adult

Question 37

You study embryos each week and note blood cells first appearing early in development. What week is it? Where are the cells made?

Answer 37

Week 3; in the yolk sac

Question 38

Identify the order in which organs become the primary site of fetal erythropoiesis.

Answer 38

Yolk sac, Liver, Spleen, Bone marrow (Young Liver Synthesizes Blood)

Question 39

What is the composition of fetal hemoglobin compared to adult hemoglobin?

Answer 39

Fetal hemoglobin (HbF) is composed of α2γ2, whereas adult hemoglobin (HbA1) is composed of α2β2

Question 40

You place adult and fetal hemoglobin in an oxygen-rich broth, then separate the two types. Oxygen content is higher on the fetal side. Why?

Answer 40

Fetal hemoglobin less avidly binds 2,3-BPG, increasing its affinity for oxygen and allowing extraction of oxygen from maternal hemoglobin

Question 41

At what point does hemoglobin composition switch from α2γ2 to α2β2?

Answer 41

Shortly after birth (Alpha Always, Beta Becomes, Gamma Goes)

Question 42

Where are the two embryonic globin subunits?

Answer 42

ε and ζ

Question 43

What is the O2 and PO2 in the blood from the placenta in the umbilical vein? How does it compare to that of umbilical arteries?

Answer 43

80% & approximately 30 mmHg; umbilical arteries have low O2 saturation

Question 44

Fetal heart chamber pressures are studied. Are pressures higher in the right or left atrium before birth? How does pressure change after?

Answer 44

Pressure in the right atrium is higher in fetal life; at birth (after the neonate takes a breath), the pressure in the left atrium is higher

Question 45

After a neonate's first breath, O2 saturation in blood ____ (↑/↓). Placental separation causes a(n) ____ (↑/↓) in prostaglandins.

Answer 45

↑ ↓ (responsible for the closure of the ductus arteriosus)

Question 46

The ____ closes with an alteration in pressure gradient across the atria. The ____ closes from decreased prostaglandin synthesis.

Answer 46

Foramen ovale (called fossa ovalis after closure); ductus arteriosus

Question 47

An infant has a patent ductus arteriosus. The drug ____ can close the ductus arteriosus. By contrast, ____ keep the ductus arteriosus open.

Answer 47

Indomethacin; prostaglandins (E1 and E2)

Question 48

Blood entering the fetus bypasses the hepatic circulation by way of the ____, which then directly enters the ____.

Answer 48

Ductus venosus, IVC

Question 49

Oxygen-rich blood primarily travels to the fetal heart via the ____ and then passes through the ____ before going into the aorta.

Answer 49

IVC, foramen ovale

Question 50

Describe the pathway by which deoxygenated blood travels from the SVC to the descending aorta. Don't forget the shunt(s)!

Answer 50

SVC to right atrium to right ventricle to main pulmonary artery to ductus arteriosus to descending aorta

Question 51

In a fetus, the fetal pulmonary artery resistance is high. How does this impact fetal circulation? What structure accommodates this?

Answer 51

Blood entering the main pulmonary artery; instead of entering the pulmonary vessels, goes to the descending aorta via the ductus arteriosus

Question 52

Blood entering the main pulmonary arteries in a fetus is preferentially shunted through the ductus arteriosus. What drives this finding?

Answer 52

Low blood O2 tension

Question 53

What does the umbilical vein become postnatally? In which structure is it contained?

Answer 53

The ligamentum teres hepatis; the falciform ligament

Question 54

What does the umbilical artery become postnatally?

Answer 54

The medial umbilical ligaments (from the umbilical artery)

Question 55

What does the notochord become postnatally?

Answer 55

Nucleus pulposus

Question 56

What does the foramen ovale become postnatally?

Answer 56

Fossa ovalis

Question 57

What does the ductus venosus become postnatally?

Answer 57

Ligamentum venosum

Question 58

What does the ductus arteriosus become postnatally?

Answer 58

Ligamentum arteriosum

Question 59

What does the allantois become postnatally?

Answer 59

Median umbilical ligament (from the allantois)

Question 60

A neonate has urine leaking from his umbilicus. An umbilical connection to the bladder is seen. What duct likely had defective development?

Answer 60

The allantoic duct (of which the urachus is a part)