Development of the Heart

Question 1

What forms the horsehoe-shaped endothelial cord?

Answer 1

Splanchnic mesoderm

Question 2

What forms the primitive heart tube?

Answer 2

Lateral body folding causes angioblastic cords to fuse together and forms the primitive heart tube

Question 3

How and when does the heart and pericardial cavity reposition?

Answer 3

Week 4 - Neural tube overgrowth pushes the heart area underneath the foregut

Question 4

What happens to the dorsal mesocardium?

Answer 4

Becomes the transverse pericardial sinus

Question 5

Sinus venosus (R horn) adult derivative

Answer 5

Sinus venarium (smooth walled portion of the right atrium

Question 6

Sinus venosus (L horn) adult derivative

Answer 6

Coronary sinus

Question 7

Primordial atrium adult derivative

Answer 7

L and R auricles

Trabeculated portions of the atria

Question 8

Primordial ventricle adult derivative

Answer 8

Left ventricle

Question 9

Primordial bulbus cordis adult derivative

Answer 9

Right ventricle

Question 10

Conus cordis adult derivative

Answer 10

outflow tract of the ventricles

Question 11

Truncus arteriosus adult derivative

Answer 11

Roots and proximal portions of the aorta and pulmonary trunk

Question 12

Blood flow through the primordial heart

Answer 12

1. Sinus venosus
2. SA canal
3. Primordial atrium
4. AV canal
5. Primordial ventricle
6. IV foramen
7. Right ventricle
8. Conus cordis
9. Truncus arteriosis
10. Aortic sac
11. Pharyngeal arteris
12. Dorsal aortae

Question 13

What causes blood flow to shift to enter the R atrium?

Answer 13

Remodeling of the Vitelline, Umbilical, and Anterior cardinal veins

Question 14

What is another effect of the Vitelline, Umbilical, and Anterior cardinal veins being remodeled?

Answer 14

The right horn of the sinus venosus becomes larger than the left horn

Question 15

Ventricular Septal Defect

Answer 15

Failure of the Interventricular septum to close

-this mixes the R and L ventricle blood, combining oxygenated and deoxygenated blood (bad)

Question 16

Transposition of the great vessels

Answer 16

The aorta and the pulmonary trunks switch places

• Nonspiraling aorticopulmonary septum
• Sends deoxygenated blood back to the body

Question 17

Tetralogy of Fallot

Answer 17

Aorticopulmonary septum doesn’t spiral evenly

• Interventricular septal defect
• Hypertrophy of R ventricle
• Overriding aorta
• Pulmonary stenosis

Question 18

What are the steps of the development of the interatrial septum?

Answer 18

1) Septum priming grows inferiorly to fuse with the endocardial cushions
2) Septum secundum forms once foramen secundum opens up
3) Both septa develop and for the interatrial septum

Question 19

How does the atrioventricular septum form?

Answer 19

The dorsal and ventral endocardial cushions join

Question 20

Why isn’t there any ventricular flow in fetal heart?

Answer 20

Because the mother provides oxygen

Question 21

Hoe does blood flow from the R atrium to the L atrium in the fetus?

Answer 21

Foramen ovale and Foramen secundum

Question 22

What happens to septum primum and septum secundum after birth?

Answer 22

Pressure in the L atrium becomes greater than the R, causing the septum secundum and primum valve system to shut, pushing blood to the lungs

Question 23

Fossa ovalis

Answer 23

Remnant of foramen ovale in mature hearts

Question 24

Muscular portion of the IV septum

Answer 24

Projection of cardiac muscles along the midline that stops short of the cushion

Question 25

Membranous portion of the IV septum

Answer 25

Made of the mesenchyme of the endocardial cushion tissue

Grows superiorly to meet the muscular portion to the create the septum

Question 26

The aorticopulmonary septum divides to creates what?

Answer 26

The aorta and pulmonary tract

Question 27

From what does the aorticopulmonary trunk derive from?

Answer 27

Endocardial cushions of the distal bulbus cordis