Cardiovascular System Development and Congenital Heart Disease

Question 1

What is the role of splanchnic mesoderm in heart development?

Answer 1

The heart itself develops from splanchnic mesoderm!

Question 2

What is the role of neural crest cells in heart development?

Answer 2

Cranial neural crest cells migrate into the developing outflow tract where they participate in the septation of the tract and formation of the aortic arches.

Question 3

Describe the major venous drainage leading to the developing heart tube.

Answer 3

Vitelline veins (portal system) drains the GI tract and carries poorly oxyenated blood

Umbilical veins carry well-oxygenated blood from the developing placenta to fetus

Cardinal veins (anterior, common, posterior) form the caval system which constitutes the main venous drainage system of the body that returns poorly oxygenated blood to the heart.

All drain into the sinus venosus of the developing heart tube.

Question 4

What is the fate of the vitelline and umbilical arteries

Answer 4

Vitelline -

Umbilical - distal part forms the medial umbilical ligaments while the proximal part remains as the internal iliac arteries and superior vesical artery

Question 5

What are the major embryological components of the eartly developing heart tube?

Answer 5

1

Question 6

To what does each developmental component contribute to the fully formed heart?

Answer 6

1

Question 7

How does differential growth of specific regions bring about the fully developed heart?

Answer 7

1

Question 8

Describe the flow of blood thorugh the primordial heart

Answer 8

1

Question 9

What is the developmental source of the smooth part of the right and left atrium?

Answer 9

1

Question 10

Describe the partitioning of the atrioventricular canal, primordial atrium and primordial ventricle?

Answer 10

Endocardial cushions composed to ECM enlarges and produces swellings that divide the atrioventricular canal to the right and left channels

The primitive ventricle is divided into right and left by the muscular (from myoblasts) and membranous interventricular septum (from fusion of bulbar ridges and endocardial cushions)

the primitive atrium is partitioned by the primary and secondary septum.

Question 11

Describe the development of the bulbar and truncal ridges and their formation of the aorticopulmonary septum.

Answer 11

Derived from neural crest mesenchyme

they form a spiral aorticopulmonary septum that divides the bulbous cordis and truncus arteriosus into the ascending aorta and the pulmonary trunk

note - the bulbu cordis becomes the conus arteriosis in the right vent and the aortic vestibule in the left vent.

Question 12

What is the significance of the spiraling in the aorticopulmonary septum?

Answer 12

It places the pulmonary trunk anterior to the aorta at the site of origin form the heart

Question 13

Describe the development of the hearts conducting system.

Answer 13

1

Question 14

Describe the ocntributions of the fourth and sixth aortic arches to the development of the major newborn structures.

Answer 14

The fourth aortic arch contributes to the actual aortic arch (left) and the right subclavian arteru

The left sixth aortic arch forms the proximal part of the left pulmonary artery and the ductus arteriosis while the right 6th aortic arch contributes to the proximal part of the right pulmonary artery

Question 15

Describe the fetal circulation .

Answer 15

The ductus venosus shunts blood form the left umbilical vein directly through the liver and into the inferior vena cava

blood form the IVC is directed through the foramen ovale into the left atrium

Most blood form the right ventricle goes through the ductus arteriosus into the aorta - only 5-10% goes to the lungs

At birth, the foramen ovale closes and the ductus arteriosus becomes hte ligamentum arteriosum

Question 16

What role do prostaglandins play in fetal circulation and how do they change at birth?

Answer 16

Increased blood oxygenation inhibits prostagladning synthesis and the release of bradykinin

bradykinin leads to contraction of the smooth muscle of the ductus arteriosus, making it close

Question 17

Describe the changes that occur to circulation after birth?

Answer 17

1. foramen ovale closes
2. dustus arteriosus becomes the ligamentum arteriosum
3. umbilical vein becomes the hepatic ligamentum teres
4. the ductus venosus becomes the ligamentum venosum
5. umbilical arteries form the medial umbilical ligaments while the proximal part remains as the internal iliac arteries and superior vesical artery