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Flashcards in CV Embryology Deck (42):
1

Steps to take in the study of heart development. 

1. What is the primordium ? How does it start?

2. What is the position ? Where is it located?

3. What is the shape or appearance? What does it look like?

4. What processes are used in the developmental process, e.g. fusion, folding, cell migration? How does it happen? 

2

When does the cardiovascular system apprear in the embryo?

It appears in the middle of the 3rd week of embryonic development and starts to function at the beginning of Week 4. 

3

The cardiovascular system is derived mainly from (a)______ mesoderm and (b)______ and (c)_______ mesoderm.

 

4

Cardiovascular System

Primordium? 

Position? 

Shape or appearance? 

Processes? 

Primordium? Angiogenic cell clusters that coalesce to give rise to vessels

Position? Cranial at first, then in the future thoracic cavity anterior to the esophagus.

Shape or appearance? A tube.

Processes? Fusion of cell clusters to form tubes, folding of embryo to move the primitive heart to its adult location 

5

The heart begins in the ______ region and during folding _____ to lie in the ____. This area of the foregut will develop into the _____. The aorta remains ______ to the foregut. 

The heart begins in the cranial-most region and during folding “swings down” to lie in the thorax. This area of the foregut will develop into the esophagus. The aorta remains posterior to the foregut. 

6

What is the primitive heart?

 

  • simple tubular dilation of cardiovascular system with cardiac muscle cells in wall
  • does not have four chambers.
  • “formation of the cardiac loop” is the name of the process of dilation, bending and folding of the tube. 

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Primitive Heart

Primordium? 

Position? 

Shape or appearance? 

Processes? 

Primordium? simple tubular dilation of cardiovascular system with cardiac muscle cells in wall

Position? anterior to the developing esophagus in the thorax.
Shape or appearance? a tube.
Processes? dilation, bending and folding of the tube. 

8

Embryonic Structure:

 

 

Truncus Arteriosus

Adult Structure:

 

aorta and pulmonary trunk

9

Embryonic Structure:

 

Bulbus Cordis 

Adult Structure:

 

smooth parts of the left and right ventricles.

 

 

10

Embryonic Structure:

 

Ventricle 

 

 

 

Adult Structure

 

11

Embryonic Stucture:

 

 

Atrium

 

Adult Structure:

 

 

trabeculated parts (pectinate muscles) of the left and right atria. 

12

Embryonic Structure:

 

Sinus Venosus

 

 

 

Adult Structure:

 

13

The developing tubular heart dilates to form _____, constricts to demarcate the transition from the ____ to the ______ and ______ and then rotates to the _______ in the _____. 

The developing tubular heart dilates to form chambers, constricts to demarcate the transition from the chambers to the outflow system and venous return and then rotates to the adult orientation in the thorax

14

_____-directional blood flow into the heart from the Sinus Venosus and away from the heart through the ________. ​

Unidirectional blood flow into the heart from the Sinus Venosus and away from the heart through the Truncus Arteriosus 

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We need multidirectional blood flow into the _____and from the ____. .


 

We need multidirectional blood flow into the atria and from the ventricles. 

16

Endocardial Cushions

 

Primordium? 

Position? 

Shape or appearance? 

Processes? 

Primordium? Endocardial cushions form from neural crest cells and mesenchymal tissue.

Position? Along the fold between the primitive atria and ventricles.

Shape or appearance? Think of it as a floor with a hole in each atrium to get to the ventricle.

Processes? Migration of neural crest cells to the area and fusion of the endocardial cushions. 

17

What are the four (4) endocardial cushions that surround the atrioventricular canal?  

anterior, posterior and 2 lateral.

 

The opposing cushions fuse to form the right and left atrioventricular canals.

The remaining more central part of the cushion tissue then forms the mitral and tricuspid valves. 

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18

Wall of Atria

Primordium? One common atrium; roof of the atrium; endocardial cushions.

Position? Along avertical line that would divide the primitive atria.

Shape or appearance? Think of it as a wall with a “one way doggy door” to connect the right and left atria.
Processes? Growth of cells from the roof of the atria and endocardial cushions; programmed cell death in the septum primum to form the foramen secundum. 

19

The septum primum (1st) is a ___________that grows _____ from the roof of the _______ and partially divides the atrium leaving a ______________allowing blood to flow from the right atrium to the left atrium. 

20

What happens to the foramen primum as the septum primum grows?

 

 

 

As the septum primum grows the foramen primum gets smaller.

21

What happens as the foramen primum becomes smaller? 

 Perforations appear in the septum primum and coalesce to form the foramen secundum (2nd opening). 

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22

The septum secundum (2nd) grows______ and gradually _____ the foramen secundum forming _______ between the atria (foramen ovale) which is covered by the flap like valve of the ______. 

The septum secundum (2nd) grows downward and gradually overlaps the foramen secundum forming an incomplete partition between the atria (foramen ovale) which is covered by the flap like valve of the foramen ovale. 

23


What does the development of the atrial septum involve? 

 

The development of the atrial septum involves the septum primum which is replaced by the septum secundum and the foramen (ostium) primum which is replaced by the foramen (ostium) secundum.

24

________ is divided into right and left atria first by the septum primum and is replaced by the septum secundum (2nd). 

The primitive atrium is divided into right and left atria first by the septum primum and is replaced by the septum secundum (2nd). 

25

What does the foramen secundum form?

The foramen secundum forms the foramen ovale and is covered by the valve of the foramen ovale. 

26

Ventricles

 

Primordium? 

Position? 

Shape or appearance? 

Processes? 

Primordium? One common ventricle; floor of the ventricle; endocardial cushions.

Position? Along a vertical line that would divide the primitive ventricles.

Shape or appearance? Think of it as a wall.

Processes? Growth of cells from the floor of the ventricles and endocardial cushions;. 

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27

Separation of the aorta and pulmonary trunk

 

Primordium? 

Position? 

Shape or appearance? 

Processes? 

Primordium? Truncus arteriosus.

Position? Along a spiraling line that would divide the truncus arteriosus.

Shape or appearance? Think of it as spiral staircase.

Processes? Growth of endocardial cushion cells along the conotruncal ridges. 

28

Separation of the aorta and the pulmonary trunk

 

As the ________________ divides the right from the left ventricle, blood is partitioned to flow into the ______ circulation from the right ventricle and into the ______ circulation from the left ventricle.

As the interventricular septum divides the right from the left ventricle, blood is partitioned to flow into the pulmonary circulation from the right ventricle and into the systemic circulation from the left ventricle. This involves the endocardial cushions again which grow toward each other like a spiral staircase so that when the growth ends the pulmonary trunk is in communication with the right ventricle and the aorta with the left ventricle. The ridges formed by the endocardial cushions are called the right and left conotruncal ridges. 

29

____________ grow toward each other like a spiral staircase so that when the growth ends the pulmonary trunk is in communication with the right ventricle and the aorta with the left ventricle.

The ridges formed by the endocardial cushions are called the right and left _____________. 

Endocardial cushions again grow toward each other like a spiral staircase so that when the growth ends the pulmonary trunk is in communication with the right ventricle and the aorta with the left ventricle. The ridges formed by the endocardial cushions are called the right and left conotruncal ridges. 

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30

Prenatal Blood Flow and Changes after Birth 

Bypasses are formed since blood does not need to circulate through the liver and lungs.

1. Ductus venosus - connects the umbilical vein with the inferior vena cava bypassing the liver.

2. Foramen ovale – connects the right atrium with the left atrium bypassing the lungs.

3. Ductus arteriosus – connects the left pulmonary artery with the arch of the aorta. 

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31

What happens after birth?

1. ductus venosus constricts to form the ligamentum venosus and blood begins to flow through the liver.

2. foramen ovale closes to form the fossa ovalis as the blood pressure increases in the left atrium.

3. ductus arteriosus constricts to form the ligamentum arteriosus due to an increase in oxygen and a decrease in circulating prostaglandins.

4. the umbilical arteries and vein constrict  

32

Selected Heart Abnormalities

 

 

Atrial septal defect

 

Patent foramen ovale: 2:1 female to male prevalence.

These defects allow interatrial shunting of blood. 

33

Selected Heart Abnormalities

 

Ostium primum defects occur ________ the tricuspid valve.

 

 

 

Ostium primum defects occur close to the tricuspid valve.

34

Selected Heart Abnormalities

 

Ostium secundum defect occur ________ from the tricuspid valve. 


 

Ostium secundum defect occur farther away from the tricuspid valve. 

35

 

 

 

Ventricular septal defect 

Ventricular septal defects are mostly an isolated defect, but can occurs with others.

These defects allow interventricular mixing of blood.

 

36

Tetralogy of Fallot

Early cyanosis - Blue baby - Most common cause of cyanosis – multiple defects.

 

1. Pulmonary stenosis
2. Ventricular septal defect
3. Overriding aorta
4. Hypertrophied right ventricle (a manifestation of items 1, 2 and 3). 

37

Transposition of great vessels

Right to left shunting - Cyanosis

Aorta rises from right ventricle.

Pulmonary trunk arises from the left ventricle.

Associated with ASD, VSD, patent ductus arteriosis.

 

38

Persistent truncus arteriosis

Right to left shunting - Cyanosis

Partial development of AV septum.

Always accompanied by membranous VSD.

 

39

ductus venosus 

ligamentum venosus and blood begins to flow through the liver 

40

foramen ovale 

fossa ovalis as the blood pressure increases in the left atrium.

41

 ductus arteriosus  

ligamentum arteriosus due to an increase in oxygen and a decrease in circulating prostaglandins

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