Cardiac Embryology

Question 1

What is different in foetus heart at 8 weeks compared to adult heart?

Answer 1

foetus heart fully developed @ 8 weeks - only difference from adult is the foramen ovale

Question 2

What does the pericardial coelom form?

Answer 2

Forms the pericardial cavity & pericardium

Question 3

what controls cardiac morphogenesis

Answer 3

Regulatory genes & transcription factors

Question 4

Why are Zebrafish good for studying embryology?

Answer 4

1 - Bred very easily & quickly - can build colonies quickly
2 - Translucent - can observe heart
3 - Probe & measure cardiac function EGG
4 - Genetically modified zebrafishes

Question 5

What is one of the last organs to develop and consequences?

Answer 5

Lungs are one of the last organs to develop - heart has to adapt without the pulmonary circulation

Question 6

The adult heart: 2 circulations:

Answer 6

1 - Pulmonary circulation - brings blood to lungs to remove Co2 & waste & bring O2 & nutrients
2 - Main circulation into systemic circulation (entire body) - wall of LV thicker

Question 7

What structures form a sac around the heart & what functions do they play?

Answer 7

Fibrous pericardium & parietal layer of serous pericardium - forms sac around heart to protect it & ensure it is fixed to environment

Question 8

Pericardial cavity function

Answer 8

Pericardial cavity is filled with fluid - avoids friction while heart is beating

Question 9

What cells make up the myocardium?

Answer 9

Cardiomyocytes - cells that contract

Question 10

Agent that causes an abnormality following fetal exposure during pregnancy

Answer 10

Teratogen

Question 11

Embryo @ 18 days: What forms the heart tubes?

Answer 11

Paired endothelial strands = Angioblastic cords in cardiogenic mesoderm canalize to form heart tubes

Question 12

What forms the tubular heart late in 3rd week?

Answer 12

Angioblastic cords in cardiogenic mesoderm canalize to form heart tubes (or endothelial tubes) that fuse to form the tubular heart

Question 13

what does the endothelial tube become?

Answer 13

endocardium

Question 14

What does the primordial myocardium become?

Answer 14

Splanchnic mesoderm –> primodrial myocardium –> Myocardium

Question 15

What do the mesothelial cells become?

Answer 15

Epicardium

Question 16

What is the bulboventricular tube?

Answer 16

Primitive cardiac tube

Question 17

What are the 7 parts of the primitive cardiac tube?

Answer 17

1 - Sinus Venosus
2 - Primitive atrium
3 - Atrioventricular canal
4 - Primitive ventricle
5 & 6 - bulbus cordis = conus cordis & primitive RV
7 - Truncus arteriosus

Question 18

Bulboventricular Loop

Answer 18

Bends in an anterior & rightward direction forming the bulboventricular loop - because bulbus cordis & ventricle grows fast

Question 19

In the sinus venosus - receives the chorion, yolk sac & embryo from which structures?

Answer 19

The sinus venosus receives the
chorion from the umbilical vein
yolk sac from vitelline vein
embryo from common cardinal veins

Question 20

Primitive atria contribute to:

Answer 20

• Superior & inferior vena cava
• Pulmonary veins
• coronary sinus
• left & right atria

Question 21

What is the atrioventricular canal?

Answer 21

Large area of connection between primitive atria & ventricle

Question 22

What does the atrioventricular canal form?

Answer 22

Endocardial cushion from specialized matrix related to myocardium
& forms parts of mitral & tricuspid valves

Question 23

What does the primitive ventricle form?

Answer 23

Left ventricle (thicker wall)

Question 24

What does the bulbus cordis form?

Answer 24

5 - primtive RV

6 - conus cordis - forms the ventricular outflow tracts (aorta & pulmonary trunk)

Question 25

What does the truncus arteriosus form?

Answer 25

Aorta & pulmonary artery trunk

Question 26

What separates the common atria into R & L halves?

Answer 26

Septum primum & septum secundum

Question 27

What do the endocardial cushion form?

Answer 27

Divides the AV into 2 orifices & parts of MV & TV

Forms part of the atrial primum septum & membranous ventricular septum

Question 28

Fetus vs After birth

Answer 28

Fetus:
- Right side high pressure (high pulmonary resistance)
- Well-oxygenated blood streams through foramen ovale
- Valve of foramen ovale closes w left atrial contraction
After birth:
- Right side low pressure (low pulmonary resistance)
- Valve remains closed (physiological closure)
- Valve eventually fuses (anatomical closure)
- Fossa Ovalis

Question 29

What are the bulbar & truncal ridges derived from?

Answer 29

Neural crest cells

Question 30

What forms the AV valves (mitral & tricuspid) & semilunar valves?

Answer 30

AV valves - formed mainly from the internal ventricular muscular wall
Semilunar valves formed from small tubercles in the truncus