Heart embryology

Question 1

From what layer does most of the CV system derive from? During what week has the cardiogenic region formed?

Answer 1

Mesoderm- some contribution from cardiac neural crest cells from ectoderm
3rd week

Question 2

What does the proximal 1/3 of the bulbus cordis give rise to? Conus cordis(lower part) gives rise to what? Truncus cordis (upper part) gives rise to what?

Answer 2

Muscular right ventricle
Smooth outflow portion of L and R ventricles
Proximal aorta and pulmonary trunk

Question 3

What does primitive ventricle give rise to? Primitive atrium? Sinus venous(right and left horns)? Aortic sac?

Answer 3

Left ventricle
Anterior of R atrium, L atrium and L and R auricles
Part of R atrium, vena cava and coronary sinus
Aorta and pulmonary artery

Question 4

By what day does heart begin to beat? Heart tube begins to fold? How do all areas of heart tube move?

Answer 4

22
23
Bulbus cordis inferiorly anteriorly and to right
Primitive ventricle= to embryos left
Primite atrium and SV= superiorly, posterior to primitive atrium

Question 5

Septation of atrium involves formation of what? What forms first and extends down towards what? What hole is present before septum premium completes fusion with endocardial cushions? Before this closes what forms?

Answer 5

Two septa and 3 holes
Septum primum–> endocaridal cushions to separate atria into 2
Foramen primum
Foramen secundum within septum primum

Question 6

What is second septum called? What hole grows within this? What 2 components does the IV septum have? What does the muscular portion do? What small gap remains?

Answer 6

Septum secundum- foramen ovale
One muscular and one membranous
Grows up from floor of ventricles towards fused endocardial cushions
Primary IV foramen

Question 7

When heart starts to beat how many atria and ventricles? Blood exits heart via what? What septum divides this into aorta and PT? What ridges grow towards each other to do this?

Answer 7

One common ventricle and one common atrium
Truncus arteriosus
Aorticopulmonary septum
Conotruncal ridges

Question 8

Between what weeks do arch vessels develop? From 1st left arch? Left 2nd arch? Left 3rd arch?

Answer 8

4-7 weeks
Part of maxillary artery
Stapedial artery
L, R, internal and external arteries

Question 9

From left 4th arch? Right 4th arch? From 6th left arch? From R 6th arch?

Answer 9

Part of aortic arch
Part of R subclavian artery
Left pulmonary artery and ductus arteriosus
Right pulmonary artery

Question 10

With first breath, increased alveolar O2 pressure causes what in pulmonary vessels? Umbilical vein into what? Umbilical arteries into what? Ductus arteriosus into what?

Answer 10

Vasodilation
Ligamentum teres
Medial umbilical ligaments
Ligamentum arteriosum

Question 11

Increased right atrial pressure causes foramen ovale closes into what? Ductus venous constricts to become what?

Answer 11

Fossa ovalis

Ligamentum venosum

Question 12

Resp tract derived from where?

Answer 12

Foregut endoderm and associated mesoderm, endoderm= epithelial lining, splanchnic mesoderm= cartilages, muscle etc

Question 13

Lung buds from during what week? Initially appears as what? What occurs during 5th week?

Answer 13

4th week
As resp diverticulum= ventral outgrowth of foregut endoderm
Buds enlarge–> L and R bronchi, pseudo glandular phase begins+ angiogenesis

Question 14

What occurs during week 16? What forms from week 24?

Answer 14

Terminal bronchioles–> terminal sacs (canalicular phase)

Alveolar sacs, type 1 and 2 pneumocytes