Thorax 06: Development Of Heart and Vessels

Question 1

Where does the splanchnic mesoderm lie before body folding?

Answer 1

Rostal to the buccopharyngeal-oropharyngeal membrane

Question 2

What embryonic tissue eventually becomes the heart?

Answer 2

Mesenchyme

Question 3

Where does heart development signalling come from?

Answer 3

Foregut floor

Question 4

[Blank] can migrate into the heart and contribute to its development

Answer 4

Neural crest cells

Question 5

Endocardium

Answer 5

Endothelium of the heart

Question 6

Myocardium

Answer 6

Middle epithelial layer of the heart

Question 7

Epicardium

Answer 7

Outer epithelia of the heart

Question 8

Dorsal mesocardium

Answer 8

The mesentery of the heart that connects it to the foregut. The venous return to the heart traverses it

Question 9

When do the two heart tubes from? When do they fuse?

Answer 9

They form in the 3rd week when the heart is folded caudally underneath the foregut floor. They fuse in the 4th week

Question 10

Cardiac jelly

Answer 10

ECM secreted by the myocardium that lies between the endocardium and myocardium

Question 11

Epimyocardium

Answer 11

Refers to the epicardium and myocardium together. Also known as myoepicardium

Question 12

What regions does a single heart tube differentiate into?

Answer 12

Sinus venous, primitive atrium, primitive ventricle, conus arteriosus, truncus arteriosus

Question 13

In the primitive heart, what is the flow of blood?

Answer 13

Sinus venous -> primitive atrium -> primitive ventricle -> conus arteriosus -> truncus arteriosus -> aortic sac -> aortic arches

Question 14

How does the heart tube fold in week 4?

Answer 14

Primitive ventricle and conus arteriosus lie ventrally and to the left. Sinus venous and primitive atrium lie dorsally. Top folds down and bottom folds up

Question 15

Where do arteries come out of? Where do veins go in to?

Answer 15

Arteries come out of front and veins go in from back. Nothing goes in the front or the bottom of the heart because of folding

Question 16

What are the four chambers of the heart?

Answer 16

Right atrium, right ventricle, left atrium, left ventricle

Question 17

Atrioventricular canal

Answer 17

A canal that forms between the primitive atrium and primitive ventricle

Question 18

How is the atrioventricular canal partitioned?

Answer 18

Dorsal and ventral walls fuse, creating right and left AV canals. These canals act as valves

Question 19

Septum primium

Answer 19

The first membrane that forms to split off right and left atria. It grows from the roof and makes its way towards the fusion of the endocardial cussions

Question 20

Foramen primium

Answer 20

A gap that acts as a shunt between the right and left atrium during development. It is bordered superiorally by the septum primium and disappears when the septum primium fuses with the endocardial cushions

Question 21

Foramen secundum

Answer 21

Gaps in the spetum primium that are caused by apoptosis of the septum, replacing the foramin primium

Question 22

Septum secundum

Answer 22

A septum that grows from the ventrocranial wall to overlap foramen secundum

Question 23

Foramen ovale

Answer 23

A valve formed in the septum secundum giving passage to oxygenated blood from the placenta, allowing it to bypass the pulmonary circuit. It fuses shut at birth

Question 24

Fossa ovalis

Answer 24

The remnant of the foramen ovale after it is fused shut

Question 25

How is the smooth wall of the left atrium formed?

Answer 25

It absorbs pulmonary vein tissue as the heart grows out. This results in separate pulmonary veins feeding into the left atrium directly and not a vein stem

Question 26

Interventricular septum

Answer 26

A muscular septum that grows from cranially from the ventricular floor to partition the primitive ventricle

Question 27

Interventricular foramen

Answer 27

Foramen that form in the interventricular septum

Question 28

When and how do the interventricular foramen close?

Answer 28

In week 7 by the fusion of the interventricular septum with the endocardial cushions

Question 29

Septation

Answer 29

Partitioning of the outflow tract

Question 30

Where do bulbar and truncal ridges originate from?

Answer 30

Neural crest cells

Question 31

Aorticopulmonary septum

Answer 31

The fusion of bulbar and truncal ridges that separates the aorta from the pulmonary trunk

Question 32

How many aortic arches are there?

Answer 32

6

Question 33

What happens to aortic arches 1 and 2?

Answer 33

They contribute to maxillary arteries

Question 34

What happens to aortic arch 3?

Answer 34

It becomes common carotid and the base of internal carotid arteries on both sides

Question 35

What happens to aortic arch 4?

Answer 35

It becomes part of the aortic arch and proximal subclavian artery

Question 36

What happens to aortic arch 5?

Answer 36

It involutes

Question 37

What happens to aortic arch 6?

Answer 37

It becomes ductus arteriosus and central part of pulmonary trunk

Question 38

What happens to the recurrent laryngeal branches?

Answer 38

Right RL nerve passes under right subclavian artery. Left RL nerve passes under aortic arch and behind ductus arteriosus

Question 39

What happens to the vitelline veins?

Answer 39

They are captured by the liver in week 7 and become the portal vein

Question 40

What happens to the umbilical veins?

Answer 40

Right one involutes, left one develops into ductus venosus

Question 41

Ductus venosus

Answer 41

A shunt that forms to send blood through liver to inferior vena cava

Question 42

Brachiocephalic vein

Answer 42

Formed by the anastomosis of the left and right cardinal veins to shunt blood to the right side of the body

Question 43

Where does the coronary sinus form from?

Answer 43

sinus venosus

Question 44

How does the foramen ovale close?

Answer 44

With respiration, there is decreased resistance in lungs, opening the pulmonary artery. The pressure differences closes the ovale and forms the fossa ovalis

Question 45

How does the Ductus arteriosus close?

Answer 45

Lung releases bradykinin which causes constriction of the smooth muscle of DA; additionally, levels of prostaglandin E decrease because there is no placenta so the DA closes

Question 46

Atrial Septal defects

Answer 46

Any set of disorders where the spetum do not properly divide the primitive atirum

Question 47

Ventricular septal defects

Answer 47

Any set of disorders where the septum do not properly divide the primitive ventricle

Question 48

Tetralogy of Fallot

Answer 48

Results from: 1) pulmonary trunk stenosis 2) hypertrophy of the right ventrical wall 3) High ventricular septal defects 4) Overriding aorta It is related to the unequal division of the conus arteriosus

Question 49

Patent ductus arteriosus

Answer 49

The flowing of blood from the aortic arch to the pulmonary trunk due to the distal part of the 6th aortic arch failing to involute

Question 50

Aortic coarctation

Answer 50

Narrowing of the aorta and can be deadly if it is post-ductus

Question 51

Truncus arteriosus

Answer 51

Incomplete separation of truncus and conus leading to fistulas between the aorta and pulmonary trunk

Question 52

Endocardial cushions

Answer 52

Structures that bulge out and develop to partition the atria from the ventricles

Question 53

What cells help form the aorticopulmonary septum

Answer 53

Neural crest cells

Question 54

What do the umbilical arteries become in the adult?

Answer 54

The medial umbilical ligaments and superior vesicular arteries