Session 3- Development of the CVS Flashcards
what is cephalo-caudal folding
brings the cardiogenic fields from the cranial end towards the centre of the embryo to sit in thoracic region where the heart will be.
what is lateral folding
fuses the two lateral sides of the embryo. This brings to two cardiogenic fields into the midline so they can fuse and form the primitive heart tube.
what does the primitave heart tube consist of
- aortic roots
- trucus arteriosus
- bulbus cordis
- primitive ventricle
- primitive atrium
- sinus venosus
what does the bulbus cordis form
involved in the formation of the pulmonary trunk and aorta
how is the primative heart tube formed
endocardial tubes are brought together by lateral folding
endocardial tubes fuse to form the primitive heart tube
cephalo-caudal folding situates the primitive heart tube in the thoracic region
in cardiac looping what direction does the primitive ventricle move
ventrally and to the right
in cardiac looping what direction does the primitive atrium move
moves dorsally and to the left
what is the transverse pericardial sinus
the cardiac looping creates a space between the aorta and pulmonary trunk and in front of the superior vena cava
what forms the right atrium
primitive atrium and sinus venosus
what forms the left atrium
from a small part of the primitive atrium and proximal portions of the pulmonary veins
what is the difference between the left and right recurrent laryngeal nerves in relation to the great vessels
right recurrent sits higher than the left the left as the 6th aortic arch degernates
how do the atrial septa form
A septum of tissue grows down from the top of the developing atria towards the endocardial cushions. This is the septum primum, and as it grows down, the communicating hole between the atria is called the ostium primum.
Just before the septum primum meets the endocardial cushions and the ostium primum is closed, a hole forms in the middle of the septum. This is the ostium secundum.
The septum primum meets the endocardial cushions, and the ostium secundum allows blood to continue to move from the right atrium to the left.
Another septum grows down from the top of the atria, called the septum secundum.
As the septum secundum grows down, it leaves another hole just below the ostium secundum.
what is the right to left shunt in the atria and what does it do
These two septa, and two holes together form the foramen ovale - a right to left shunt allowing blood to flow from the right atrium into the left.
formation of ventricular septum
The formation of the ventricular septum take place in two steps.
First, a muscular portion of heart tissue grows upwards from the floor of the primitive ventricle towards the endocardial cushions. It doesn’t quite reach the cushions, forming the primary interventricular foramen.
A membranous portion then grows down from the endocardial cushions to meet the muscular portion and close the foramen.
separation of the outflow tract
In the beginning of this process, there are two lines of proliferations of neural crest cells on the walls of the outflow tract.
These two lines of cells spiral around and grow towards each other to meet in the middle. This form a single spiral septum called the aorticopulmonary septum – consequently forming the aorta and pulmonary trunk.
what does the 6th aortic arch go onto form
goes on to form the right and left pulmonary arteries arising from the pulmonary trunk.
how does the left artery of the pulmonary artery maintain its connection to the aorta
the ductus arteriosus
what does the fourth arch form
on the left side becomes the arch of the aorta, and on the right becomes the right subclavian
what does the third arch go onto form
becomes the common carotids and the first part of the internal carotids.
what causes the ductus arteriousus to close
When the baby takes its first breath, the pO2 increases. This change causes the ductus arteriosus to close.
Ductus arteriosus becomes the ligamentum arteriosum.
what causes the foramen ovale to close
More blood now flows through the pulmonary circulation as blood in the pulmonary trunk cannot leave via the ductus arteriosus anymore. This causes increased venous return to the left atrium, leading to an increase in left atrial pressure. The pressure in the left atrium exceeds that of the right, which causes the foramen ovale to close.
Foramen ovale becomes the fossa ovalis.
what causes the ductus venosus to collapse
When the umbilical cord is cut, there is no longer blood flowing through the umbilical vein, causing the ductus venosus to collapse.
Ductus venosus becomes the ligamentum teres.
