Cardiovascular Development

Question 1

Cardiogenic Field

Answer 1

Horse-shoe shaped, located around anterior and lateral positions of neural plate. Hemangioblasts will coalesce and form primitive heart, vessels, and blood cells.

Question 2

Cardiogenic cords =

Answer 2

endocardial heart tubes

Question 3

1. Antero-posterior folding of the embryonic disc

Answer 3

Caudal portions of endocardial heart tubes (which will be heart and dorsal/ventral aortas) make contact with developing venous system.

Question 4

2. Formation of the cardiac tube

Answer 4

Horse-shoe shaped heart tube is epithelial cells until the caudal portion fuses and becomes surrounded by myoblasts to form the myocardium.

Question 5

Components of the cardiac tube

Answer 5

Bulbus cordis - precursor of R ventricle
Ventricle
Atrium (joins the venous system)

Question 6

3. Loop formation

Answer 6

Will result in the formation of the blood pumping organ for survival of the neonate. Happens in conjunction with the division of the heart into the 4 chambers.

Question 7

Primitive atrium is divided into

Answer 7

Left and right atria

Question 8

Primitive ventricle is divided into

Answer 8

Left and right ventricles

Question 9

Truncus arteriosus is divided into

Answer 9

Outflow tracts of the aorta and pulmonary trunk

Question 10

Steps in heart development (atrial partitioning)

Answer 10

1. Primary atrial septum forms. Primary foramen (ostium primum) present.
2. Development of interventricular septum begins
3. Primary atrial septum fuses with endocardial cushions and secondary foramen (ostium secundum) forms.
4. Secondary atrial septum forms, and foramen ovale between 1* and 2* septa connects right and left atria.
5. Interventricular septum has fused with the endocardial cushions.

Question 11

Septum primium will serve as

Answer 11

the valve of the Foramen Ovale, preventing return of blood into R atrium.

Question 12

At what point in development does the foramen ovale close?

Answer 12

After birth, lungs expand with first breaths, creating a decrease in vascular resistance in the lungs and dropping BP in the pulmonary circulatory system, which assists in closing the foramen ovale.

Question 13

Truncus arteriosus

Answer 13

Cranial. Divided into ascending aorta and pulmonary trunk by spiral septum with 2 ridges.

Question 14

Aorto-Pulmonary septum

Answer 14

Develops when the 2 ridges of the spiral septum of the truncus arteriosus fuse.

Question 15

Function of the spiral formation of the spiral septum

Answer 15

Ensures that blood from the right ventricle flows into the pulmonary trunk and blood from the left ventricle flows into the ascending aorta.

Question 16

If the spiral septum was straight instead…

Answer 16

“transposition of the great vessels”. Deoxy blood from right ventricle flows into ascending aorta, and highly oxygenated blood flows from the left ventricle into the lungs. Not compatible for life.

Question 17

Patent Ductus Arteriosus

Answer 17

Ductus arteriosus fails to close after birth. One of the most common congenital anomalies in domestic animals.

Question 18

Ventricular Septal Defect

Answer 18

Defect in the ventricular septum. Leaves space between right and left ventricles, from pin sized to leaving one common ventricle.

Question 19

Persistent Right Aortic Arch

Answer 19

An embryonic arch of the aorta fails to regress and is wrapped around the esophagus. Causes megaesophagus.