Cardiac Embryology (Part 2): Topic 6 Flashcards

1
Q

When does heart folding occur?

A

Day 23-28

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2
Q

Heart undergoes a series of folding that leads to the formation of what?

A

Bulboventricular loop

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3
Q

Heart Tube grows rapidly in length, especially what section?

A

The midsection (Bulbus Cordis and Ventricle)

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4
Q

Because the two ends of the heart tube ends are fixed, the heart tube is forced to do what?

A

Bend in order to adapt itself into the pericardial space; forms a U-shape, then forms an S-shape.

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5
Q

How is the heart tube oriented when it is bending?

A

Oriented so that the atrium and sinus venosus lie superior to the bulbus cordis, ventricle and dorsal aorta/aortic sac

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6
Q

Heart Folding: Atria initially paired- forms what?

A

Common atrium

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7
Q

Heart Folding: Atrioventricular junction remains narrow. Forms what?

A

AV Canal; connects common atrium and ventricle

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8
Q

Bulbus Cordis is narrow, expect what? What will this form?

A

Proximal 1/3; will form trabeculated part of the RV

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9
Q

Heart Folding: Junction between the ventricle and the bulbus cordis externally is what?

A

Bulboventricular sulcus; remains narrow and is called the primary interventricular foramen

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10
Q

Atrial portions of the Heart Tube dilate and form what?

A

Common atrium

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11
Q

Atrium “climbs up” what? What does it take with it?

A

The dorsal pericardial wall; takes atrioventricular junction with it

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12
Q

Atrioventricular junction remains narrow and is now called what? Forms the communication between what?

A

AV Canal; forms the communication between the atrium and the primitive ventricle

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13
Q

What is the junction of the ventricle and bulbus cordis called?

A

Intraventricular foramen

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14
Q

What two areas does the diverticular appear at Day 24?

A
  1. Along the front of the endocardial tube

2. Just proximally and distal to the primary interventricular foramen

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15
Q

Early embryonic ventricle is what?

A

The primitive LV

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16
Q

Proximal 1/3 of the bulbus cordis is what?

A

The primitive RV

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17
Q

What gives the densely trabeculated appearance?

A

The diverticula

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18
Q

The trabeculae inside the heart leads to what?

A

Valves, chordae tendinae, papillary muscles, and atrioventricular valves

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19
Q

Abnormalities in Cardiac looping is responsible for which cardiac defects?

A

Ventricular inversion (corrected transposition)
Juxtaposition of the atrial appendages
Double outlet right ventricle

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20
Q

BC

A

Bulbus cordis (RV)

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21
Q

AS

A

Aortic sac

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22
Q

TA

A

Truncus arteriosus

23
Q

CC

A

conus cordis

24
Q

SV

A

sinus venosus

25
Q

As the primitive atria grow, the truncus arteriosus is positioned in what depression?

A

A depression between the roof of the right and left primitive atria

26
Q

During atrial septation, the left atrium begins to form what?

A

Sprouts of the pulmonary veins that grow towards the lungs

27
Q

What day does cardiac septation?

A

Starts at Day 27

28
Q

How long does cardiac septation last?

A

Lasts 10 days (Day 27-day 37)

29
Q

During septation, the embryo grows how much?

A

5mm to 16-17mm

30
Q

Describe the changes in external appearance during the formation of the cardiac septa.

A

None

31
Q

What is the name of the narrow channel that connects the primitive right and left ventricles at day 27?

A

Interventricular Formaen

32
Q

How does blood reach the primitive LV ?

A

Via small opening from the primitive atria (AV canal)

33
Q

During ventricular development, what 2 important processes occur simultaneously that result in the “chamberization” of the ventricles?

A
  1. Division of the AV canal into a right and left av orifice vai the endocardial chusions
  2. ventricular septations
34
Q

Where do endocardial cushions develop?

A

Develop in the atrioventricular and conotruncal regions

35
Q

Endocardial cushions assist in the formation of what?

A

The atrial and ventricular (membranous septa), AV Canals, Valves, Aortic and pulmonary channels

36
Q

At the end of week 4, atrioventricular endocardial cushions appear where?

A

At the AV Canal; 2 lateral AV cushions appear on the right and left side of the canal

37
Q

When is the complete division of the canal into the right and left AV orifices final?

A

At the end of week 5

38
Q

What is the role of the endocardial cushion? What eventually occupies the resulting canals?

A
  1. Form a barrier between the atria and ventricles
  2. Right-left division of the canal

The resulting canals are eventually occupied by the mitral and tricuspid valves

39
Q

When does ventricular septation occur?

A

At the end of Week 4

40
Q

The ventricular septum is formed by what?

A

The outgrowth of the muscular ridge at the interventricular foramen; 2 primitive ventricles expand; medial wallas become apposed and merge

41
Q

How does the ventricular septum grow?

A

Upward from the apex of the heart to the base of the heart

42
Q

What is the space above the membranous septum called?

A

Interventricular foramen

43
Q

When does the interventricular foramen shrink?

A

When the conus septum is complete

44
Q

What closes the foramen during ventricular septation?

A

Outgrowth of tissue form the endocardial cushion along the top of the muscular interventricular septum closes the foramen; fuses with the abutting part of the conus septum

45
Q

At what day do the paired atria fuse together to form a common atrium

A

AT day 27-28

46
Q

Atrial septation occurs simultaneously and in cooperation with what?

A

Ventricular septation

47
Q

Atrial septation lasts how many days?

A

Approx 10 days

48
Q

What is the first portion of the septum primum?

A

Sickle-shaped crest grows from the roof of the common atrium

49
Q

What is the ostium primum?

A

Formed by the opening between the lower rim of the septum primum and the endocardial cushions

50
Q

what forms the ostium secundum?

A

Apoptosis (cell death) makes perforations in the upper part of the septum primum

51
Q

When do opposing ridges appear in the truncus?

A

By the 5th week

52
Q

What divides the truncus into aortic and pulmonary channels?

A

Aorticopulmonary septum

53
Q

Semilunar Valaves

A

Small tubercles found on main truncus swellings; tubercles hollow out on the upper surface

54
Q

At what day are the valves fully developed?

A

Day 55