Cardiovascular - Embryology

Question 1

Which layer is most of the CV system derived from?

Answer 1

Mesoderm

Question 2

What does the primary heart field develop into?

Answer 2

Future left ventricle

Question 3

What does the secondary heart field develop into?

Answer 3

Outflow tracts, future left and right atria, future right ventricle

Question 4

Name the 3 stages of cardiac formation

Answer 4

1 - Primitive heart tube formation
2 - Cardiac looping
3 - Cardiac septation

Question 5

Describe the formation of the primitive heart tube

Answer 5

• Day 19, 2 endocardial tubes fuse

Question 6

List the parts of the primitive heart tube

Answer 6

• Truncus arteriosus
• Bulbos cordis
• Primitive ventricle
• Primitive atrium
• Left and right horn of sinus venosus

Question 7

Describe cardiac looping

Answer 7

• On day 23 - 28.
• Cranial end folds ventrally and caudally (forwards and down) and shifts right.
• At same time, caudal end fold dorso-cranially and shifts to left.

Question 8

What is cardiac looping caused by?

Answer 8

Differential growth rates of the heart.

Question 9

Where are atria in relation to ventricles after cardiac looping?

Answer 9

Atria end up behind ventricles

Question 10

What structure does the truncus arteriosus give rise to?

Answer 10

• Ascending aorta

- Pulmonary trunk

Question 11

What structure does the bulbus cordis give rise to?

Answer 11

• Smooth part (outflow tract) of L+R ventricles

Question 12

What structure do the endocardial cushions give rise to?

Answer 12

• Atrial spetum
• Interventricular septum
• AV and semilunar valves

Question 13

What structure does the primitive atrium give rise to?

Answer 13

• Trabeculated parts of the atria

Question 14

What structure does the primitive ventricle give rise to?

Answer 14

• Trabeculated parts of the ventricles

Question 15

What does the right horn of the sinus venosus give rise to?

Answer 15

• Smooth part of right atrium

Question 16

What structure does the left horn of the sinus venosus give rise to?

Answer 16

• Coronary sinus

Question 17

What structure does the primitive pulmonary vein give rise to?

Answer 17

• Smooth part of left atrium

Question 18

What structure do the primitive right common carotid and right anterior cardinal veins give rise to?

Answer 18

• Superior vena cava

Question 19

Describe atrial cardiac septation

Answer 19

• 2 endocardial cushions form on dorsal and ventral walls of atria.
• They grow towards each other and fuse = AV canal.
• Septum primum then grows from superior aspect of atrium. Gap between it and cushions = foramen primum.
• Another space opens up in septum primum = foramen secundum, and the foramen primum closes.
• Septum secundum then begins to grow from top and bottom, next to septum primum.
• Top part of septum primum begins to disappear.
• Gap between septum secundum from top and septum primum from bottom = foramen ovale.

Question 20

Describe ventricular septation

Answer 20

• Ventricle had a membranous and muscular septum growing from apex.
• Walls grow and fuse together = interventricular septum

Question 21

What does the 1st aortic arch give rise to?

Answer 21

Regresses and forms part of maxillary artery (in face)

Question 22

What does the 2nd aortic arch give rise to?

Answer 22

Regresses and forms part of stapedial artery (in ear)

Question 23

What does the 3rd aortic arch give rise to?

Answer 23

Internal and common carotid arteries

Question 24

What does the 4th aortic arch give rise to?

Answer 24

Right: Part of right subclavian artery
Left: Part of aortic arch

Question 25

What does the 5th aortic arch give rise to?

Answer 25

Nothing - either regresses or develops partially then regresses

Question 26

What does the 6th aortic arch give rise to?

Answer 26

Right: Right pulmonary artery Left: Left pulmonary artery and ductus arteriosus

Question 27

Describe foetal circulation

Answer 27

- Maternal circulation - Placenta - Umbilical vein - Some to liver, 1/3 to ductus venosum - Liver straight to RA, ductus venosum to IVC then RA - Some to LA through foramen ovale, so to RV - RV to pulmonary artery then aorta via ductus arteriosus. LA to LV then aorta. - Aorta to umbilical arteries - Back to maternal circulation

Question 28

What does the ductus venosum become at birth?

Answer 28

Ligamentum venosum

Question 29

What does the ductus arteriosus become at birth?

Answer 29

Ligamentum arteriosus

Question 30

What does the foramen ovale become at birth?

Answer 30

Fossa ovalis

Question 31

What does the umbilical vein become at birth?

Answer 31

Ligamentum teres hepatis

Question 32

What does the umbilical artery become at birth?

Answer 32

Medial umbilical ligament

Question 33

When does vasculogensis commence?

Answer 33

Day 18

Question 34

What is vasculogenesis?

Answer 34

Differentiation of angioblasts into endothelial cells which form a primitive vascular network.