Embryology of the CVS 1 Flashcards
What are the four major stages in heart development?
- Primitive heart tube
- heart looping
- artial and ventricular septation
- outflow tract septation
Name the labelled parts.
Which mesoderm goes on to form the circulatory system (and other viscera)?
lateral plate splanchnic mesoderm
Why does the primordial heart start to function at the beginning of week four, and why is CVS the first major system to develop in the growing embryo?
In a rapidly growing embryo, diffusion is not sufficient to supply required nutrients therefore embryo must utilise CVS.
__________ ______ _______ collect in the lateral plate splanchnic mesoderm, move towards the midline and coalesce to form the two _________ ________ _______.
Angiogenic cell islands
primitive heart tubes
Blood vessels first appear in the wall of _____ _____, ______, _______ _____ and ______.
yolk sac
allantois
connecting stalk
chorion
Appearance of paired endothelial strands (_________ _______) appear in the cardiogenic mesoderm – 3rd week
angioblastic cords
Angioblastic cords canalize to form _____ ________.
heart tubes
Tubular heart joins blood vessels in other areas to form _________ _________ _______.
primordial cardiovascular system
During cranial folding, reorientation of the heart tube positions it ________ to pericardial cavity.
dorsal
Cephalic folding
pericardial cavity: _____ - _______
cardiac tube: _______ - ______
dorsal - ventral
ventral - dorsal
Pericardium is derived from i______ ______ _______.
intra-embryonic coelom
Parietal layer of serous pericardium & fibrous pericardium are formed from _______ _________.
somatic mesoderm
Visceral layer of serous pericardium is derived from __________ ________.
splanchnic mesoderm
Name the labelled parts.
Which part becomes the arterial system?
Which part becomes the venous system?
Arterial system = cephalic end
venous system = caudal end
Name the labelled parts of the fused primitive heart tube.
The venous end of the heart tube is called the what?
sinus venosus
Each horn of the sinus venosus gets blood from which areas?
(3)
placenta
yolk sac
body of the embryo
What are the names of the veins which drain blood into the sinus venosus?
Where do they drain blood from?
(3)
umbilical vein = placenta
vitelline vein = yolk sac
common cardinal vein = body of the embryo
The arterial end of the heart tube is known as the what?
truncus arteriosus
The truncus arteriosus is continuous cranially with the _______ _______.
What arises from the structure labelled above?
aortic sac
aortic arches
How many aortic arches are there on each side?
Aortic arches terminate in the ______ _______.
6
dorsal aorta (R & L)
_____________ and ________ grow faster than other regions forming a U-shaped ___________ loop.
Bulbus cordis
ventricle
bulboventricular
Name the labelled parts of the looped heart tube.
What is dextrocardia?
Heart points to the right side of the chest instead of the left side.
What happens during dextrocardia?
Heart tube loops to the left side instead of the right (so ends up to lie facing the right).
What can dextrocardia be associated with?
Situs inversus (transposition of viscera)
What does partitioning of the primordial heart involve?
One or two actively growing masses of tissues:
Endocardial cushion formation
Septum formation
What does the endocardial cushion do?
Seperates RA and RV from LA and LV, forming left and right AV canals.
What does the septum formation do?
Separates RA from LA and RV from LV.
What are cardiac malformations associated with defective formation of endocardial cushion and septum formation?
Atrial septal defect (ASD)
Ventricular septal defect (VSD)
Name the labelled parts.
What develops during the partition of the primitive atrium?
1) Septum primum and foramen primum
2) Septum secundum and foramen secundum
What is another word for foramen?
Ostium
What is the role of the oval foramen before birth?
Allows most of the blood to pass from the right atrium to the left atrium (non-functioning lungs).
Prevents the passage of blood in the opposite direction.
______ _______ of adult heart is a remnant of foetal oval foramen.
Fossa ovalis
When the foramen ovales closes after birth, which structures meet?
septum primum (inferior)
septum secondum (superior)
Non closure of formamen ovales results in what?
What is the clinical term for this?
patent formamen ovale
atrial septum defect (ASD) = ‘hole in the heart’
What are the four clinically significant types of atrial septal defect (ASD)?
A) Foramen secundum defect
B) Endocardial cushion defect with foramen primum defect
C) Sinus venosus defect
D) Common atrium
Partitioning of Primitive Ventricle
What is the initial septum formed, what does this create?
muscular interventricular septum
interventricular foramen
What is the name of the structure which divides the bulbis cordis and truncus arteriosus?
aorticopulmonary septum
What causes the closing of the interventricular foramen?
What does this form?
The attachment of the aorticopulmonary septum with the muscular interventricular septum.
They meet to form the membraneous interventricular septum.
Growth of ______ _______ also contributes to membranous portion of the interventricular septum.
endocardial cushions
What is the most common type of congenital heart disease (25% of cases)?
Who is this most common in?
ventricular septal defect (VSD)
males
Where do early pacemakers develop?
(2)
Primitive atrium and then sinus venosus
Where is the SA node located in adults?
very proximal to the opening for the SVC, high in the RA
What does cot death or sudden infant death syndrome (SIDS) often occur due to?
Abnormalities of conducting tissue
What adult structure(s) does the truncus arteriosus develop into?
aorta and pulmonary trunk
The smooth part of the right ventricle is called the what?
conus arteriosus
The smooth part of the left ventricle is called what?
aortic vestibule
The primitive ventricle develops into which adult structures?
trabeculated parts of the L & R ventricles
The primitive atrium develops into which adult structures?
trabeculated parts of L & R atria
The sinus venosus develops into which adult structures?
smooth part of right atrium
coronary sinus
The junction of the trabeculated and smooth parts of the right atrium is called the what?
crista terminalis
What are the causes of congenital heart disease?
(5)
Rubella infection in pregnancy
Maternal alcohol abuse
Maternal drug/radiation treatment
Genetics
Chromosomal
Tetralogy of Fallot is associated with which four major defects?
- Pulmonary stenosis
- Ventricular septal defect (VSD)
- Dextroposition of aorta (“overriding” aorta)
- Right ventricular hypertrophy
