CVS Embryology 1: Heart Development.

Question 1

When do angiogenic clusters appear?

Answer 1

In the middle of the third week.

Question 2

What forms angiogenic clusters?

Answer 2

Mesenchymal cells in the splanchnic (vesiral) layer of the mesoderm proliferate and form isolated cell clusters known as angiogenic clusters.

Question 3

Where are angiogenic clusters first located?

Answer 3

In the lateral side.

Question 4

Where do angiogenic clusters rapidly spread to?

Answer 4

To the cephalic end.

Question 5

The angiogenic clusters acquire what?

Answer 5

A lumen.

Question 6

Angiogenic clusters unite to form what?

Answer 6

A horseshoe-shaped plexus of small blood vessels.

Question 7

The anterior portion of the angiogenic plexus is called what?

Answer 7

Central portion of cardiogenic area.

Question 8

The intraembryonic colemic cavity located over the blood vessel plexus later form what?

Answer 8

Pericardial cavity.

Question 9

After formation of neural tube and brain vesicles CNS grown rapidly in which direction?

Answer 9

The cephalic direction.

Question 10

What happens when neural tube and brain vesicles CNS grows rapidly in the cephalic direction?

Answer 10

It extends over the cardiogenic area and future pericardial cavity.

Question 11

The percordial plate and the cardiogenic plate are pulled towards which direction?

Answer 11

Forward.

Question 12

The cardiogenic plate and pericardial cavity become located where?

Answer 12

Ventrally and caudally.

Question 13

List the 2 folds that bring the 2 heart tubes of an early embryo together?

Answer 13

1- folds in cephalocaudally (cranial fold).
2- then transversely (lateral fold).

Question 14

The 2 endocardial heart tube in an early embryo fuse in which direction?

Answer 14

Cephalo-caudally.

Question 15

The heart tube is attached to which side of the pericardial cavity?

Answer 15

Doral side of the pericardial cavity.

Question 16

The heart tube of an early embryo is attached to the dorsal side of the pericardial cavity by what?

Answer 16

Dorsal mesocardium.

Question 17

The mesoderm adjacent to the endocardial tube forms what?

Answer 17

Epimyocardial mantle.

Question 18

The epimyocardial mantle is separated from endocardial tube by what?

Answer 18

Cardiac jelly.

Question 19

The endocardial tube of an early embryo consists of what?

Answer 19

1- endocardium.
2- myocardium.
3- epicardium.

Question 20

The cephalic portion of the heart tube bends in which direction which creates the cardiac loop?

Answer 20

Ventral and caudal direction to the right.

Question 21

The caudal portion of the heart tube bends in which direction which creates the cardiac loop?

Answer 21

Shifts in a dorsal-cranial direction and to the left.

Question 22

The 2 bends of the heart tube creates what?

Answer 22

A cardiac loop.

Question 23

List the 4 twists of a primitive heart tube in order from top to bottom?

Answer 23

1- bulbus cordis.
2- ventricle.
3- atrium.
4- sinus venosus.

Question 24

The atrioventricular junction remains narrow and develops into what?

Answer 24

Atrioventricular canal.

Question 25

List the 3 parts of the bulbus cordis?

Answer 25

1- proximal third. 2- conus cordis (middle part). 3- truncus arteriosus (distal part).

Question 26

What does the proximal third of the bulbus cordis form?

Answer 26

Forms the trabeculated (rough) part of the right ventricle.

Question 27

What does the conus cordis (middle third) of the bulbus cordis form?

Answer 27

Forms the outflow tract (smooth side) of both ventricles.

Question 28

What does the truncus arteriosus (distal third) of the bulbus cordis form?

Answer 28

Forms the aorta and pulmonary trunk.

Question 29

The proximal portion of the bulbus forms what?

Answer 29

The primitive right ventricle.

Question 30

The primitive ventricle become what to later form what?

Answer 30

Becomes trabeculated (rough) and forms the primitive left ventricle. (Rough part of the left ventricle).

Question 31

In which week does the sinus venosus consist of a transverse portion and right and left sinus horn?

Answer 31

4th week.

Question 32

Each horn receives blood from 3 important veins, list them?

Answer 32

1- vitelline veins (venous drainage of the GIT). 2- the umbilical vein. 3- common cardinal vein (venous drainage of the whole body).

Question 33

Which part of the horn disappears in the 5th and 7th week?

Answer 33

The left umbilical vein and left vitelline vein.

Question 34

Which part of the horn disappears in the 10th week?

Answer 34

The left common cardinal vein.

Question 35

List the remaining part un the left horn of sinus venosus?

Answer 35

1- the oblique vein of left atrium. 2- the coronary sinus.

Question 36

Due to left to right shunt what happens to the right sinus horn and veins?

Answer 36

They enlarge.

Question 37

What is the only communication between sinus venosus and the atrium?

Answer 37

The right horn.

Question 38

The right horn is incorporated into right atrium to form what?

Answer 38

The smooth part of the right atrium.

Question 39

What are endocardial cushions?

Answer 39

Dorsal (ant.) and ventral (post.) swellings.

Question 40

Endocardial cushions fuse, dividing the single AV canal into what?

Answer 40

Paired canals.

Question 41

Endocardial cushions are involved in the formation of what?

Answer 41

Formation of interatrial and interventricular septa.

Question 42

Endocardial cushions are derived from what?

Answer 42

Neural crest.

Question 43

Endocardial cushions are involved in which medical conditions?

Answer 43

In many CHDs (congenital heart diseases).

Question 44

List the 5 arterial septums in order?

Answer 44

1- septum primum. 2- foramen primum. 3- foramen secundum. 4- septum secundum. 5- foramen ovale.

Question 45

Septum primum grows from what?

Answer 45

Atrial roof toward endocardial cushions.

Question 46

What is foramen primum?

Answer 46

Shunt that closes.

Question 47

What does foramen secundum do?

Answer 47

Perforates septum primum, allowing shunt.

Question 48

What does septum secundum do?

Answer 48

Grows down, overlapping foramen secundum.

Question 49

Where is foramen ovale located?

Answer 49

Between septum primum and septum secundum.

Question 50

How does foramen ovale close in a fetus?

Answer 50

1- right side high pressure (high pulmonary resistance, ect.). 2- well oxygenated blood streams through foramen ovale. 3- valve of foramen ovale closes with left atrial contraction.

Question 51

What happens to foramen ovale after birth?

Answer 51

1- right side low pressure (low pulmonary resistance). 2- valve remains closed (physiological closure). 3- valve eventually fuses (anatomical closure).

Question 52

What is foramen ovale called after it fuses?

Answer 52

Fossa ovalis.

Question 53

Which partitioning is not part of fetal circulation?

Answer 53

Ventricular partitioning.

Question 54

Ventricular septum closes in which week?

Answer 54

Week 7.

Question 55

List the 2 types of ventricular septum?

Answer 55

1- muscular. 2- membranous.

Question 56

Muscular IV septum grows from what?

Answer 56

Floor.

Question 57

Membranous inter ventricular (IV) septum forms from what?

Answer 57

Endocardial cushions and bulbar ridges.

Question 58

Closure of membranous IV is associated with what?

Answer 58

Partitioning of tuncus arteriosus.

Question 59

Partitioning of truncus arteriosus is a continuous set of what?

Answer 59

Ridges in bulbus cordis (bulbar ridges) and truncus arteriosus (truncal ridges).

Question 60

Partitioning of truncus arteriosus grow in which direction?

Answer 60

Towards each other, spiraling 180.

Question 61

Partitioning of truncus arteriosus fuse to form what?

Answer 61

Spiraling aorticopulmonaryseptum, dividing aorta and pulmonary trunk.

Question 62

Bulbular ridges are involved in the formation of what?

Answer 62

Formation of IV septum.

Question 63

Bulbar and truncal ridges are derived from what?

Answer 63

Neural crest cells.

Question 64

List the 2 types of VSD?

Answer 64

1- membranous (= perimembranous, conoventricular) VSD. 2- muscular VSD.

Question 65

What is the most common CHD?

Answer 65

Membranous (perimembranous, conoventricular) VSD.

Question 66

Membranous (perimembranous, conoventricular) VSD is more common among which gender?

Answer 66

Males > females.

Question 67

What happens in membranous VSD?

Answer 67

Endocardial cushions and bulbar ridges fail to fuse with musc. septum.

Question 68

Muscular VSD is located where?

Answer 68

In muscular IV septum.

Question 69

What is the supracristal VSD?

Answer 69

Muscular VSD.

Question 70

What is the least common VSD?

Answer 70

Muscular VSD.

Question 71

List the 4 types of atrial septal defects (ASD)?

Answer 71

1- (ostium) secundum ASDs. 2- AV septal defect (AV canal). 3- patent foramen (ostium) primum. 4- sinus venosus ASDs.

Question 72

What is the most common ASD?

Answer 72

(ostium) secundum ASDs.

Question 73

(ostium) secundum ASDs is more common with which gender?

Answer 73

Females > males.

Question 74

(ostium) secundum ASDs is due to what?

Answer 74

Problems with septum primum (perforated or too short), but sometimes septum secundum or both septa.

Question 75

AV septal defect (AV canal) is due to what?

Answer 75

Endocardial cushion problems so that septum primum never fuses with cushion tissue.

Question 76

A patent foramen (ostium) primum causes what?

Answer 76

Valve defects.

Question 77

Patent foramen (ostium) primum is due to what?

Answer 77

Sometime no fusion of endocardial cushions: AV septal defects.

Question 78

Patent foramen (ostium) primum is found in 20% of which patients?

Answer 78

Downs patients.

Question 79

Which ASD is very rare?

Answer 79

Sinus venosus ASDs

Question 80

Which CHD is 5-7% of all CHDs?

Answer 80

Tetralogy of fallot.

Question 81

What is tetralogy of fallot?

Answer 81

Four co-occurring heart defects.

Question 82

List the 4 co-occurring heart defects found in tetralogy of fallot?

Answer 82

1- pulmonary stenosis. 2- ventricular septal defect. 3- overriding aorta (dextroposition). 4- right ventricular hypertrophy.

Question 83

Tetralogy of fallot is due to what?

Answer 83

Asymmetrical fusion of bulbar and truncal ridges.