Cardiac Embryology Flashcards
What is different in foetus heart at 8 weeks compared to adult heart?
foetus heart fully developed @ 8 weeks - only difference from adult is the foramen ovale
What does the pericardial coelom form?
Forms the pericardial cavity & pericardium
what controls cardiac morphogenesis
Regulatory genes & transcription factors
Why are Zebrafish good for studying embryology?
1 - Bred very easily & quickly - can build colonies quickly
2 - Translucent - can observe heart
3 - Probe & measure cardiac function EGG
4 - Genetically modified zebrafishes
What is one of the last organs to develop and consequences?
Lungs are one of the last organs to develop - heart has to adapt without the pulmonary circulation
The adult heart: 2 circulations:
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
What structures form a sac around the heart & what functions do they play?
Fibrous pericardium & parietal layer of serous pericardium - forms sac around heart to protect it & ensure it is fixed to environment
Pericardial cavity function
Pericardial cavity is filled with fluid - avoids friction while heart is beating
What cells make up the myocardium?
Cardiomyocytes - cells that contract
Agent that causes an abnormality following fetal exposure during pregnancy
Teratogen
Embryo @ 18 days: What forms the heart tubes?
Paired endothelial strands = Angioblastic cords in cardiogenic mesoderm canalize to form heart tubes
What forms the tubular heart late in 3rd week?
Angioblastic cords in cardiogenic mesoderm canalize to form heart tubes (or endothelial tubes) that fuse to form the tubular heart
what does the endothelial tube become?
endocardium
What does the primordial myocardium become?
Splanchnic mesoderm –> primodrial myocardium –> Myocardium
What do the mesothelial cells become?
Epicardium
What is the bulboventricular tube?
Primitive cardiac tube
What are the 7 parts of the primitive cardiac tube?
1 - Sinus Venosus 2 - Primitive atrium 3 - Atrioventricular canal 4 - Primitive ventricle 5 & 6 - bulbus cordis = conus cordis & primitive RV 7 - Truncus arteriosus
Bulboventricular Loop
Bends in an anterior & rightward direction forming the bulboventricular loop - because bulbus cordis & ventricle grows fast
In the sinus venosus - receives the chorion, yolk sac & embryo from which structures?
The sinus venosus receives the
chorion from the umbilical vein
yolk sac from vitelline vein
embryo from common cardinal veins
Primitive atria contribute to:
- Superior & inferior vena cava
- Pulmonary veins
- coronary sinus
- left & right atria
What is the atrioventricular canal?
Large area of connection between primitive atria & ventricle
What does the atrioventricular canal form?
Endocardial cushion from specialized matrix related to myocardium
& forms parts of mitral & tricuspid valves
What does the primitive ventricle form?
Left ventricle (thicker wall)
What does the bulbus cordis form?
5 - primtive RV
6 - conus cordis - forms the ventricular outflow tracts (aorta & pulmonary trunk)
What does the truncus arteriosus form?
Aorta & pulmonary artery trunk
What separates the common atria into R & L halves?
Septum primum & septum secundum
What do the endocardial cushion form?
Divides the AV into 2 orifices & parts of MV & TV
Forms part of the atrial primum septum & membranous ventricular septum
Fetus vs After birth
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
What are the bulbar & truncal ridges derived from?
Neural crest cells
What forms the AV valves (mitral & tricuspid) & semilunar valves?
AV valves - formed mainly from the internal ventricular muscular wall
Semilunar valves formed from small tubercles in the truncus
