Embryology: Development Of Pericardium And Heart Tube

Question 0

Describe endocardial tube formation

Answer 0

Blood islands cluster, form a lumen, and form a plexus of blood vessels
Bilateral endocardial tube forms from the plexus of blood vessels
Endocardial tubes unite to form the primitive heart tube

Question 1

When and where does heart development begin?

Answer 1

End of the third week of gestation

Occurs in ventral region of embryo, inferior to foregut

Question 2

When does the single heart tube begin to form?

Answer 2

Day 21-22

Question 3

How does the heart tube elongate?

Answer 3

Cells from the secondary heart field are added to the cranial end of the tube

Question 4

What happens of lengthening of the heart tube does not occur?

Answer 4

Outflow tract defects (DORV, VSD, TOF, PA, PS)

Question 5

Blood islands inferior to the pericardial tubes form the:

Answer 5

Dorsal aortas

Question 6

Two functions of dorsal aortas:

Answer 6

Connect endocardial tubes

Establish the arterial end of the heart

Question 7

What happens to the heart tube on day 23?

Answer 7

Cephalic part bends ventrally, Caudally, and to the right
Caudal part bends Dorsocranially and to the left
Tube bulges into pericardial cavity and eventually is suspended there

Question 8

6 regions of heart tube

Answer 8

Dorsal aorta and aortic sac
Bulbus cordis
Primitive ventricle
Atrioventricular sulcus
Paired primitive atria
Sinus venosus

Question 9

Dorsal aorta and aortic sac become:

Answer 9

Outflow tract

Question 10

Bulbus cordis becomes:

Answer 10

RV

Question 11

Primitive ventricle becomes

Answer 11

LV

Question 12

Atrioventricular sulcus becomes:

Answer 12

Divides atria from ventricles

Question 13

Paired primitive atria becomes:

Answer 13

Common atria

Question 14

Sinus venosus becomes:

Answer 14

Coronary sinus and oblique vein of LA

Question 15

Heart folding day 23-28

Answer 15

Folds to form bulboventricular loop
Midsection of heart tube rapidly lengthens (Bulbus cordis and ventricle)
Heart forms U shape–> S shape
Oriented so atrium and sinus venosus are superior to the Bulbus cordis, ventricle, and dorsal aorta

Question 16

Proximal third of the Bulbis cordis forms:

Answer 16

Trabeculated part of RV

Question 17

Atrium folding of the heart

Answer 17

1. Atrial portions of heart tube dilate (form common atrium)
2. Atrium climbs up dorsal pericardial wall taking AV junction with it
3. AV junction remains narrow (called AV canal)

Question 18

Ventricle folding of heart tube

Answer 18

1. Ventricle dilates acquiring larger lumen

2. Junction of ventricle and Bulbis cordis remains narrow (intraventricular formamen)

Question 19

Heart folding: Bulbis cordis

Answer 19

1. Dilation of Bulbis cordis

2. Growth continues at venous pole until have a midportion and right and left horns

Question 20

2 sharply defined areas of the diverticula (day 24)

Answer 20

1. Front of endocardial tube

2. Just proximal and distal to interventricular foramen

Question 21

Function of diverticula on heart

Answer 21

Expand capacity of heart

Give densely Trabeculated appearance

Question 22

Trabeculae inside heart lead to:

Answer 22

Valves
Chordae tendinae
Papillary muscles
AV valves

Question 23

Cardiac defects caused by abnormalities in cardiac looping

Answer 23

Ventricular inversion, juxtaposition of atrial appendages, DORV

Question 24

What do the right and left valves that flank the sinuatrial orifice become?

Answer 24

Left venous valve: fuses with atrial septum
Superior part of right venous valve: disappears
Inferior part of right venous valve: becomes valve of IVC and valve of coronary sinus

Question 25

During atrial septation, where do pulmonary veins arise from?

Answer 25

Left atrium