Embryology of the CVS 1 Flashcards
what is bilateral heart primordia
bilateral groups of cells consisting of 3 rows,
1 row of endocardial precursors medially
2 rows of myocardial precursors laterally
what begins the heart development?
the formation of 2 endocardial tubes, these 2 tubes merge to form the primitive heart tube
what is the tubular heart also known as
the primitive heart tube
what happens to the primitive heart tube?
it loops and separates into the 4 heart chambers and paired arterial trunks that form the adult heart
state the first stage of heart development
formation of the primitive heart tube
state the second stage of heart development
heart looping
looping of the primitive heart tube
state the third stage of heart development
atrial and ventricular septation
state the fourth stage of heart development
outflow tract septation
what does the lateral plate splanchnic mesoderm form in the 3rd week?
it forms the circulatory system
what collects in the lateral plate splanchnic mesoderm?
angiogenic cells islands
what is the intermediate mesoderm
it is a type of mesoderm, intermediate cell mass
where is the intermediate mesoderm located?
it is located between the paraxial mesoderm and the lateral plate mesoderm
what does the intermediate mesoderm develop into?
it develops into the part of the urogenital system as well as the reproductive system
what is the first major system to function in the embryo?
the cardiovascular system
when does the primordial heart start to function?
at the beginning of the 4th week after fertilisation
where do blood vessels first appear in the embryo?
they first appear in the wall of the yolk sac,a allantois, connecting stalk and chorion
when do angioblastic cords appear in the cardiogenic mesoderm?
in the 3rd week
what do angioblastic cords canalise to form?
heart tubes
what are the origin of the heart tube?
clusters of angiogenic cells
where are the clusters of angiogenic cells located?
they are located in the caridogenic plate
what is the cardiogenic plate derived from?
the splanchnopleuric mesoderm
where is the cardiogenic plate located?
it is located cranial and lateral to the neural plate
what is the yolk sac?
it is a membrane outside the embryo
what is the yolk sac connected by?
it is connected by a tube through the umbilical opening to the embryo’s midgut
what does the old sac serve as?
it serves as an early site for the formation of good and in time, is incorporated into the primitive gut of the embryo
what is the amniotic cavity?
it is the fluid-filled space between the amnion and foetus
what are angioblastic cords?
they are any of the cord-like masses of splanchnic mesenchymal cells ventral to the primordial coelom
how are the angioblastic cords arranged?
they arrange themselves side by side to form the primordial of the endocardial tubes
what are the angioblastic cord also called?
they are also called an angiogenic cell cluster
what angioblastic cords?
they are endothelial cords in the cardiogenic mesoderm of the embryo that appears in the 3rd week of gestation
what does the tubular heart form when joint to blood vessels in other area?
the primordial cardiovascular system
when does the development of the pericardium take place?
in the early part of stage 9, roughly the 25th day, during the 5th week
describe the development of the pericardium
lateral structures called pleuropericardial folds begin to grow towards the midline, bringing along the phrenic nerves as they move medially, the root of each fold migrates ventrally
what occurs during the end of the 5th week in terms of the development of the pericardium
the pleuropericardial folds fuse, partitioning the thoracic cavity into the pericardial cavity and 2 partially formed pleural cavities
what is the pericardium derived from?
the intraembryonic coelom
what are the parietal layers of the serous pericardium and the fibrous pericardium formed from?
the somatic mesoderm
what is the visceral layer of the serous pericardium derived from?
the splanchnic mesodern
what does the caudal end of the bulbs cordis give rise to?
it gives rise to the mouth parts of the left and right ventricles
what does the cranial end of the bulbus cordis give rise to?
it gives rise to the aorta and the pulmonary trunk with the truncus arteriosus
what is dextrocardia?
it is a rare heart condition in which your heart points toward the right side of your chest instead of your left side
what kind of condition is dextrocardia?
it is a congenital condition
what can dextrocardia be associated with?
situs inversus
what is the most frequent positional abnormality of the heart?
dextrocardia
define endocardial cushion formation?
the right atrioventricular opening is separated from the left atrioventricular opening forming the left and right atrioventricular canals
state the 2 ways in which the primordial heart is partitioned?
endocardial cushion formation and septum formation
describe briefly septum formation
a septum is formed when the right ventricle is separated from the left ventricle
the right atrium being separated from the left atrium also forms a septum
what does endocardial cushions refer to?
it refers to a subset of cells in the development of the heart that play a vital role in the proper formation of the heart septa
in reference to endocardial cushions, when does this subset of cells develop?
these cells develop on the atrioventricular canal and conotruncal region of the bulbus cordis
define the septum primum
it is a thin, crescent-shaped membrane that grows down from the roof of the primitive atrium, towards the developing endocardial cushions
define the sinoatrial valve
it is the valve at the sinoatrial orifice at the opening of the sinus venosus into the primordial right atrium
define the foramen ovale
it is an opening in the septum between the 2 atria of the heart that normally present only in the foetus
when does the develop of the foramen ovale occur?
at the end of week 4, it is a sickle shaped crest that grows from the roof of the atrium
define the ostium primum?
it is the opening between the septum premium and endocardial cushion
define the role of the foramen ovale
it is a hole in the intertribal septum to shunt oxygenated blood from the right atrium to the left atrium
describe the foramen ovale in more detail
it is an anaemic adaptation in the foetus to allow oxygenated blood coming from the umbilical vein via the inferior vena cava to bypass the pulmonary circulation
define what an atrial septal defect is
it is a hole in the wall that separates the top 2 chambers of the heart
how many types of clinically significant atrial septal defects are there?
4
state the 4 significant types of atrial septal defects
foramen secundam defect
endocardial cushion defect with foramen premum defect
sinus venosus defect
common atrium defect
state the two most common types of atrial septal defects
the foramen secundum defect and the endocardial cushion defect
describe basically what an atrial septal defect is
it is a defect in the septum between the two upper heart chambers, that allows oxygen-rich blood to leak into the oxygen-poor blood chambers in the heart
define the inter-ventricular septum
it is the stout wall separating the ventricles of the heart form one another
define the aorticopulmonary septum
it is the septum that actively separates the aorta and pulmonary arteries and fuses with the inter-ventricular septum within the heart during heart development
what is the aorticopulmonary septum developmentally formed from?
the cardia neural crest
define the ventricular septal defect
it is essentially a hole in the septum that separates the hearts ventricles
what type of defect is the ventricular septal defect
it is a congenital defect, i.e. it is a defect that is present at birth, and this defect is relatively common
what does the ventricular septal defect allow?
it allows blood to pass from the left to the right side of the heart
when does the partitioning of the bulbus cordis and truncus arteriosus occur?
during week 5 of development
what is formed during the partitioning of the bulbus cordis and truncus arteriosus?
bulbar ridges and truncal ridges
what does the septum partitioning the bulbus cordis and the trunks arterioles divide in to?
the bulbus cordis and the truncus arterioles divides into the aorta and the pulmonary trunk
define the cardiac conduction system
it is a group of specialised cardiac muscle cells in the walls of the heart that send signals to heart muscle causing it to contract
state the 5 major components of the cardiac conduction system
the sinoatrial nodes the atrioventricular nodes the bundle of His the bundle branches the purkinje fibres
define congenital heart disease
it is a malformation of the heart, aorta or other large blood vessels
what is one of the most frequent forms of major birth defects in newborns?
congenital heart disease
what does much of the practice of paediatric cardiology consist of?
the diagnosis and treatment of congenital heart disease
what is situs inversus
it is an uncommon condition in which the heart and other organs of the body are transposed through the sagittal plane to lie on the opposite side from the usual
what is transposition of great vessels
it is a group of congenital heart defects involving an abnormal spatial arrangement of any of the great vessels
what do the great vessels include?
the superior vena cava the inferior vena cava the pulmonary artery the pulmonary veins the aorta
what is transposition of great vessels the common cause of?
cyanotic disease in newborn infants
what does transposition of great vessels permit the exchange of?
systemic and pulmonary circulation
what does transposition of great vessels cause?
failure of the aorticopulmonary septum to take a spiral course and defective migration of neural crest cells
what is tetralogy of fallot?
it is a congenital heart condition involving 4 abnormalities occurring together
what are the 4 cardiac defects making up the condition of tetralogy of fallot?
pulmonary stenosis
ventricular septal defect
dextropostion of aorta
right ventricular hypertrophy
what does tetralogy of fallot cause?
unequal division of the conus due to anterior displacement of the aorticopulmonary septum
how can tetralogy of fallot be described?
defective septum between the ventricles
narrowing of the pulmonary artery
cyanosis can be accompanied with this condition
what is pulmonary stenosis
it is a condition in which the pulmonary valve is too tight, flow of blood from the right ventricle of the heart into the pulmonary artery is therefore impeded
what is the number of babies born with ventricular septal defect
at least 1/500 babies are born with this disease
what type of defect is ventricular septal defect
it is a congenital condition
describe a ventricular septal defect
it is essentially a hole in the septum between the ventricles
what is the most common type of heart malformation
a ventricular septal defect
define dextropostion of the aorta
it is when the aorta sits in the middle of both ventricles as opposed to coming off the left ventricle only
define right ventricular hypertrophy
it is a form of ventricular hypertrophy affecting the right ventricle
foramen oval of the developing heart is an opening in which embryonic structure?
the septum secundum
