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Flashcards in 11.22 B Deck (97):
1

What are the endocardial tubes?

lines of embryonic heart precursor cells that will give rsie to the primitive heart tube

2

The medial endocardial tubes give rise to what?

the dorsal aortae

3

The lateral endocardial tubes give rise to what?

venous structures

4

Cranial folding on day 20 gives rise to what embryonic heart changes?

- formation of the aortic arch
- fusion of the right and left endocardial tubes

5

Describe the sequence of blood flow through the primitive heart tube.

sinus venosus to atrium to ventricle to bulbus cordis to aortic sac

6

When does the embryonic heart start to beat?

it starts beating on day 22 but with little directionality

7

What is the truncus arteriosus?

the part of the primitive heart tube that will give rise to the ascending aorta and pulmonary trunk

8

What is the sinus venosus?

the primitive heart structure that gives rise to the right atrium and coronary sinus

9

What events give rise to the pericardial sinuses?

folding of the primitive heart tube

10

What is cardiac jelly?

ECM secreted in between myocardium and primitive endothelium of the heart tube

11

The pericardial sac forms from what embryonic cell population?

mesothelial cells

12

From inside out, what are the four layers of the heart tube?

- endocardium (primitive endothelium)
- cardiac jelly (ECM)
- myocardium
- epicardium (visceral pericardium)

13

During folding of the heart tube, the bulbus cordis is displaced in which direction?

inferiorly, ventrally, and to the right side of the body

14

Duringn folding of the heart tube, the sinus venosus is displaced in which direction?

superiorly and posteriorly

15

What is dextrocardia?

improper twisting of the heart tube such that the base of the heart is directed to the right side of the body

16

What is the difference in prognosis between those with dextrocardia and those with situs inversus?

those with just dextrocardia are more likely to have additional heart defects while those with situs inversus only have a slightly increased risk

17

Endocardial cushions form what?

the septum intermedium which separates the atrium from ventricles

18

What is the septum intermedium?

the structure that separates the atrium from the ventricles

19

What is the septum primum?

a crescent-shaped structure that grows down from the superoposterior wall of the atrium to begin forming the left and right atrium

20

What is the ostium primum?

the opening in the septum primum between the left and right atrium

21

What is the ostium secundum?

an opening that forms in the septum primum before closure of the ostium primum to keep the right and left atria connected

22

Endocardial cushion cells are derived from what?

neural crest cells

23

Why do individuals that suffer from craniofacial defects often also have congenital heart defects?

because both are due to neural crest cell defects

24

Neural crest cell deficits often disrupt formation of what heart structures?

endocardial cushions

25

Endocarial cushion defects can lead to what heart defects?

- atrial and ventricular septal defects
- atrioventricular defects
- transposition of the great vessels

26

What is an atrioventricular canal?

an atrioventricular septal defect (aka an endocardial cushion defect)

27

People with Down Syndrome commonly have what heart defect?

an atrioventricular septal defect

28

How does an atrioventricular septal defect often present?

- tachypnea
- poor feeding (need to breath instead)
- growth retardation
- typically identified around 6 weeks
- cyanosis sometimes seen

29

What is the foramen ovale?

an opening in the septum secundum

30

The foramen ovale and ostium secundum allow for what throughout embryonic development?

blood flow from the right to left atrium

31

A one way intraatrial valve is formed by what structures during embryonic development?

the septum secundum (an its foramen ovale) and the ostium secundum in the septum primum

32

In adults, an atrial septal defect allows flow of blood in which direction?

left to right atrium

33

What symptoms are present with an atrial septal defect?

- often very few
- shortness of breath
- easy fatigue
- poor growth

34

What murmur most often accompanies an atrial septal defect?

an S2 split thanks to delayed pulmonic valve closure due to more blood passing through the right side of the heart

35

How is an atrial septal defect often treated?

by placing a septal occluder and without open heart surgery

36

How does a secundum atrial septal defect arise?

poor growth of the septum secundum leaves overlap between the foramen ovale and the ostium secundum

37

How does a patent foramen ovale develop?

from failure of the two atrial septa to fuse

38

A patent foramen ovale doesn't often lead to problems because...

as long as pressure in the left atrium is higher than that of the right, the foramen ovale "valve" is kept shut

39

A patient presents with fixed splitting of the second heart sound, an ejection murmur, right ventricular conduction delay, and enlargement of the right heart. You suspect what?

an atrial septal defect

40

Patent foramen ovale are most problematic because they can lead to what?

paradoxical embolization

41

What is a paradoxical embolization?

an embolus arising in the systemic venous system or right atrium crosses the patent foramen ovale and enters systemic arterial circulation

42

The smooth walls of the atria are derived from what heart tube structure?

the sinus venosus

43

What is the interventricular septum?

the divider between the two ventricles

44

What is the interventricular foramen?

the hole between the two ventricles left by the halted growth of the muscular interventricular septum

45

The interventricular septum is composed of what two portions?

the muscular and the membranous

46

How are ventricular septal defects treated?

most close on their own by age 5

47

What is the truncus arteriosus?

the structure that will give rise to both the aorta and the pulmonic trunk

48

What are conotruncal swellings?

ridges that develop in the truncus arteriosus wall that will divide it into the aorta and pulmonic trunk

49

The conotruncal swellings of the truncus arteriosus are derived from what cell population?

neural crest cells

50

Failure to form the septum of the truncus arteriosus outflow tract leads to what problems?

- transposition of the great arteries
- pulmonary stenosis
- persistent truncus arteriosus
- tetraology of Fallot

51

How does transposition of the great vessels present?

with cyanosis

52

Infants with transposition of the great vessels can live longer without treatment if what occurs?

persistent or patent foramen ovale or patent ductus arteriosus

53

What is the ductus arteriosus?

a vessel connecting the pulmonary artery to the proximal descending aorta

54

What is persistent truncus arteriosus?

failure of the truncus arteriosus to divide and give rise to the aorta and pulmonary trunk

55

Persistent truncus arteriosus presents with what?

cyanosis and death unless corrected

56

What is the tetraology of Fallot?

- ventricular septal defect
- pulmonary stenosis
- aorta that overrides both ventricles
- hypertrophy of right ventricle

57

When is tetraology of Fallot typically detected?

months to years after birth

58

How does tetraology often present?

sudden incidence of cyanosis with hyperpnea between 2 mo and 2 yrs old

59

The severity of Tetraology of Fallot is largely dictated by what factor?

the degree of pulmonary stenosis

60

How does pulmonary stenosis present?

- usually asymptomatic unless the individual is exercising
- if more severe, there may be a an S2 split

61

S2 splitting is most often indicative of what?

pulmonary stenosis

62

Rheumatic disease can sometimes lead to what heart defect?

aortic valve stenosis

63

Aortic valvular stenosis leads to what secondary problem?

enlargement of the aortic arch

64

How do chordea tendonae form?

through programmed cell death

65

What is the ligamentum arteriosum?

the remnants of the ductus arteriosus

66

What is special about ductus arteriosus smooth muscle?

it is induced to contrcat upon exposure to oxygen

67

Coarctation of the aorta is due to what?

malpositioning of the ductus arteriosus smooth muscle

68

Hypertension in the upper extremities and hypotension in the lower is the hallmark of what defect?

coarctation of the heart

69

How does coarctation of the heart often present?

- upper extremity hypertension and lower extremity hypotension
- left ventricular hypertrophy
- pain upon exercise in lower limbs

70

Notching of the lower surface of the ribs is indicative of what heart defect?

coarctation of the aorta

71

The third aortic arch often gives rise to what adult structures?

internal carotid artery

72

The fourth aortic arch often gives rise to what adult structures?

the right subclavian artery and arch of the aorta

73

The sixth aortic arch often gives rise to what adult structures?

the pulmonary arteries and ligamentous arteriosus

74

What is the embryonic importance of the ductus arteriosus?

connect the pulmonary arteries to the arch of the aorta thus bypassing the fetal lungs

75

The aortic arches are surrounded by what nerves?

the left and right recurrent laryngeal nerve

76

Name the three arteries that come off the aortic arch?

- brachiocephalic
- left common carotid
- left subclavian

77

Aortic/branchial arch anomalies often lead to what?

disrupted breathing and problems swallowing

78

What are the vitelline veins?

those serving the yolk sac

79

What are the umbilical veins?

those serving the placenta

80

What are the cardinal veins?

those serving the embryo

81

What are the three pairs of veins returning blood to the embryonic heart at the sinus venosus?

- vitelline
- umbilical
- cardinal

82

How does venous return shift during development?

initially, cardinal veins are bilateral with return of teh blood to both horns of teh sinus venosus, but then there is a shift to the right

83

The superior vena cava is derived from what?

the right anterior cardinal vein

84

The inferior vena cava is derived from what embryonic structure?

the inferior vitelline vein

85

The right horn of the sinus venosus becomes what?

part of the right atrium

86

The left horn of the sinus venosus becomes what?

the coronary sinus

87

The portal vein in liver develops from what?

vitelline veins

88

What is the ductus venosus?

a channel through the liver that allows blood from the left umbilical vein directly through the liver to the inferior vena cava

89

What happens to the left umbicial vein in the liver?

- at first it enlarges to become the ductus venosus
- then it involutes after birth to form the ligamentum venosum

90

The ductus venosus is derived from what embryonic vein?

the left umbilical vein

91

Prior to birth, what are the two shunts that allow right to left blood flow to bypass the fetal lung?

- foramen ovale
- ductus arteriosus

92

What role does bradykinin play in the cardiovascular system immediately at birth?

it serves to decrease the vascular resistance within the lung as the oxygen source changes

93

What happens to right arterial pressure just after birth?

it declines as umbilical blood flow is lost

94

What molecule reduces the vascular resistance of the lungs just after birth?

bradykinin

95

What is indomethican?

a prostaglandin inhibitor given to speed up the closure of the patent ductus arteriosus

96

Why would transposition of the great arteries be treated with prostaglandin?

prostaglandin will slow closure of the ductus arteriosus allowing some oxygenated blood from the right ventricle to reach the systemic arteries

97

A machine like murmur present during systole and diastole and cyanosis of just the toes is indicative of what?

patent ductus arteriosus