Cardiovascular Development

Question 1

Nkx2.5

Answer 1

Homeobox gene req for normal cardiac development

Question 2

Which direction does fetal blood flow/does the heart develop?

Answer 2

caudal to rostral

Question 3

What is looping?

Answer 3

Twisting of the heart pushes the future atria from caudal position to a more rostral and posterior position.

Question 4

What is myocardial trabeculation?

Answer 4

Differentiation of pulmonary and aortic tubes, occurs at the same time as looping

Question 5

What does the bulbus cordis become?

Answer 5

Conus cordis
-cardiac outflow tract (transient structure that connects the ventricles to the aortic sac)

Truncus arteriosus
-Pulmonary artery and aorta

Question 6

What cells form the cardiac valves?

Answer 6

AV canal/endocardial cushions undergo epithelial to mesenchymal transition and migrate into the cardiac jelly

Question 7

What is septation?

Answer 7

Process of separating the pieces of the heart

Question 8

What is the septum primum?

Answer 8

Part of atrial septation. Grows from dorsal wall of atria towards the AV cushions (the hole that is not yet closed by the septum is called the ostium premum).

Small holes form in the septum premum towards the dorsal wall.

Question 9

What is the septum secundum?

Answer 9

It grows outward from the superior wall of the atria, very close to the septum primum. This forms a second layer of tissue that also maintains a hole that is offset from the ostium secundum. These overlaid layers of tissue become the atrial septum, with holes forming the foramen ovale.

Question 10

Ostium secundum ASD

Answer 10

Most common type of ASD. Occurs in center of septum between right and left atria.

Due to incomplete formation of the septum secundum or incomplete active closure of ostium secundum

Question 11

Ostium primum ASD

Answer 11

Leads to problems with AV valves

Due to incomplete active closure of the ostium primum

Question 12

Sinus venosus ASD

Answer 12

Least common, located in upper portion of atrial septum

Due to a defect in formation of septum primum and is often associated with an abnormal pulmonary vein being connected to RA instead of LA.

Question 13

Which arch becomes the main aortic arch?

Answer 13

Left 4th arch, while the right 4th arch degenerates

Question 14

What is DiGeorge Syndrome?

Answer 14

Chromosomal deletion that leads to defects in NC migration .Can include a patent truncus arteriosus (because NC cells are req for septation)

Question 15

How is the L–>R axis thought to be determined?

Answer 15

By embryonic cilia

Question 16

What is dextrocardia?

Answer 16

When heart is a mirror image–heart tube loops left instead of right, otherwise heart is normal. Fine as long as all organs are flipped also (situs inversus)

Question 17

What is Heterotaxy?

Answer 17

When some organs are flipped and some are not. this is a problem

Question 18

How are the valves formed?

Answer 18

Endothelial cells migrate into cardiac jelly and become mesenchymal cells. These groups of cells become endocardial cushions and eventually mature into valve leaflets.

Question 19

What pathway governs valve formation?

Answer 19

Ras pathway

-link between leukemia and valvular diseases

Question 20

What are semaphorins

Answer 20

key regulators of vasculogenesis that are repulsive signals of vasculature

Question 21

What do cells in the epicardium contribute to?

Answer 21

Multipotent cells that give rise to fibroblasts in the heart, coronary arteries