Embryology of the CVS - NOT COMPLETE

Question 1

What does the heart begin as?

Answer 1

Bilateral heart primordia

Question 2

What is the order of heart development?

Answer 2

• Formation of the primitive heart tube
• Heart looping
• Atrial and ventricular septation
• Outflow tract seperation

Question 3

Which germ layer does the circulatory system originate?

Answer 3

Mesoderm

Question 4

What part of the mesoderm does the circulatory system arise from?

Answer 4

Lateral plate splanchinic mesoderm

Question 5

How does the two primitive heart tubes form?

Answer 5

Angiogenic cell islands move toward the midline and coalesce

Question 6

Why is the heart one of the first functioning organ of the embryo?

Answer 6

Diffusion becomes diffucult as size increases

Question 7

What areas of the embryo do blood vessels first appear?

Answer 7

• Yolk sac
• Allantois
• Connecting stalk
• Chorion

Question 8

What tubes canalize to form the heart tubes?

Answer 8

Angioblastic cords

Question 9

What does the pericardium develop from?

Answer 9

Intra embryonic coelom

Question 10

What part of the mesoderm do the parietal and serous pericardium form from?

Answer 10

Somatic mesoderm

Question 11

What layer of the pericardium forms from the splanchnic mesoderm?

Answer 11

The visceral layer

Question 12

Describe the different layers of the primitive heart tube from arterial (cranial) end to venous (caudal) end

Answer 12

Question 13

What way does the primitive heart tube loop?

Answer 13

Anti clockwise

Question 14

Which two parts of the primitive heart tube grow the fastest to form the cardiac loop?

Answer 14

Bulbus Cordis and Ventricle hence the name bulboventricular loop

Question 15

How does dextrocardia occur?

Answer 15

The heart tube loops to the left side instead of the right and eventuall then faces the right

Question 16

What is endocardial cushion formation?

Answer 16

Seperates right atrioventricular opening from left atrioventricular opeing

Question 17

What two cardiac malformations can occur when endocardial cusion formation and septum formation go wrong?

Answer 17

• Atrial septal defect
• Ventricular septal defect

Question 18

Study the diagram referring to the left and right AV canals

Answer 18

Question 19

How does the primordial atrium partition into a left and right atria?

Answer 19

Formation of 2 septa and two foramina to eventually result in the fossa ovale

Question 20

What is the opening between the septum primum and the endocardial cushion called?

Answer 20

Ostium Primum

Question 21

What is the role of the foramina ovale before birth?

Answer 21

Allows blood to pass from the right to left atrium without entering the pulmonary system as the lungs are not functioning

Question 22

What is a clinical sign of atrial septal defect?

Answer 22

Blue baby

Question 23

How does blood not flow back through the septum?

Answer 23

Acts as a valve

Question 24

What are the four types of ASD?

Answer 24

• Foramen secudnum defect
• Endocardial cushion defect with foramen primum defect
• Sinus venosus defect
• Common atrium

Question 25

Describe the partitioning of the primordial ventricle

Answer 25

• Muscular ventricular septum forms (opening known as interventricular foramen
• Aorticpulmonary septum rotates and fuses with muscular ventricular septum to form membranous interventricular septum (this closes the interventricular foramen
• Growth of endocardial cushion seperaties atria and contributes to the membranous portion of the interventricular septum

Question 26

What are the early heart pacemakers?

Answer 26

Primordial atrium then sinus venosus

Question 27

What does the AV node and bundle of his develop from?

Answer 27

Cells of AV canal and sinus venosus

Question 28

What can occur from abnormalities of the conducting syndrome?

Answer 28

Sudden infant death syndrome

Question 29

What does the aortic sac form?

Answer 29

Aortic arches

Question 30

What does the bulbus codis form?

Answer 30

Right ventricle and part of the outflow tracts

Question 31

What does the primitive ventricle form?

Answer 31

Left ventricle

Question 32

What does the primitive atrium form?

Answer 32

Parts of left and right atrium

Question 33

What does the sinus venosus form?

Answer 33

SVC

Right atrium

Question 34

What are the multifactorial aetiologies of congenital heart disease?

Answer 34

• Rubella infection in pregnancy
• Maternal alcohol abuse
• Maternal drug treatment and radiation
• Genetic
• Chromosomal

Question 35

What is transpositiong of great vessels?

Answer 35

When the pulmonary trunk and the aorta join to the wrong ventrivle and the ductus arteriosis remains open