Development of the Cardiovascular System Flashcards
Identifiy the chambers of the early heart
Which is the input side, which is the output side?
input: caudal
outpud: cranial
What is the name of the region where the heart begins to form?
Describe the composition of the early heart
Primary Heart Field
mesenchyme coalesce into two early heart tubes, which will meet in the midline to fuse into a singular heart tube
epithelial lining (endocardium), and a developing group fo muscle progenitor cells (myocardium), and outer mesothelial covering (epitcardium)
The dorsal mesocardium suspends the heart from the ventral surface of the notochord
What is the name fo the dorsal and ventral expansions of the endocardium between the atrium and the ventricle?
What structurs are formed when they fuse?
endocardial cushions
The grow toward midline and fuse, forming right and left atrioventricular canals
The caudal and cranial mesocardium attachments cause the early heart to change shape in what ways as it dilates and elongates
initially a more gently C-shaped bend, but continues to a more severs S-shaped bending (facilitates division into 4 chambers)
asymmetry wil develop, and the formaiton fo a four chambered heart
The internal partitioning of the heart occurs in what 4 major steps?
- the atrioventricular canals
- the subdivision of the atrium
- the subdivision of the ventricle
- the subdivision of the truncus anteriosus
Describe the formation of the early valve separating two atria
septum primum; on cranial margin, extending caudaly & fusing with endocardial cushions
leaves an opening called the foramen primum, that allows blood to flow between the two atria; septum primum seals this feature, but apoptosis occus more cranial forming a second hole, the foramen secumdum
then a ticker, more muscular septum, Septum Secundum, forms to the right of the septum primum, with a gap called the foramen ovale
the septum primum becomes a valve over the left surface of the foramen ovale
blood passes from right to left
Describe the process of ventricular partitioning
From anterior side, the interventricular septum extends into the ventricle, but does not reach the atrioventricular septum. The passage above this septum is termed the interventricular foramen
The aorticopulmonary septum forms from cardiac neural crest cells and extends into the ventricles as the Bulbar Ridge, opposite the inventriular septum
A second septum will come down off the Bulbar Ridge and sit on the right side of the muscular interventricular septum, sealing the interventricular foramen
What are the 4 major steps in creating the subdivision of the truncus arteriosus
- neural crest migrate into the bulbus/truncus junction and form two opposing trunconal cushions
- the trunconal cushions fuse in the midline to form the aorticopulmonary septum
- the aorticopulmonary septum extends proximally and distally, spiraling as it does so
- At its proximal end the septum (bulbar ridge) fuses with the membranous ventricular septum
What heart features are formed from the following primordial structure?
Truncus Areriosus
Bulbus Cordis
Ventircle
Atrium
Sinus Venosus
- Right and left Pulmonary arteries
- Truncus Areriosus
- Pulmonary Trunk
- Ascending Aorta
- Bulbus Cordis
- Aortic Vestibule in left ventricle
- Infundibulum/Conus Arteriosus in right ventricle
- Ventircle
- all of left ventricle except hte aortic vestibule
- all of right ventricle except he infundibulum/conus arteriosus
- Atrium
- all of left atrium; right atrium except sinus venarum
- 2 pulmonary veins from each lung grow into the left atrium
- Sinus Venosus
- fuse together
- Left coronary sinus
What are the 3 embryonic circulatory circuits?
- Vitelline
- associated with yolk sac adn developing digestive tract
- Umbilical
- between placenta and the embryo
- Cardinal
- between embryo’s body and the heart
What 3 vitelline arteries remain?
- Celiac: foregut
- Superior Mesenteric: midgut
- Inferior mesenteric: hindgut
Describe the route of the vitellin veins
paired vitelline veins extend from yok sac, paralleling th the developing digestive system & pass through the transverse septum to enter the sinus horns
the liver develops between the paird veins & they expand w/ the developing liver to form the vitellin plexus
they form part of the inferior vena cava and the hepatic sinusoids; caudal to the liver, the left vitelline vein is lost, while the right forms the hepatic portal system
Describe the course of the umbilical arteries their branches
initially arise from the dorsal aorta, but migrate to internal iliac arteries
paired umbillical arteries course on either side of the bladder, then in umbilical cord to reach the placenta
at birth, proximal end remains as portion for the internal iliac, superior vesicular artery (a distal segment), and most of the umbilical arteris will fill with connective tissue to form the medial umbilical ligaments
Describe the progression of the umbilical veins
- Paired umbilica veins extend from the placenta and enter the sinus horms
- as liver develops, umbilical veins drain into that organ and lose their connection to the sinus venosus
- the right umbilical vein regresses, all the way back to the placenta
- the umbilical veing (left) not connects to the inferior vena cava by way of a shunt throught he liver, the ductus venosus
Describe the path of the aortic arches
initially, trucus arteriosus leads to an expanded aortic sac that courses anteriorly and gives rise to 5 paired aortic arches, which run in the pharyngeal arches
5th arch never forms, (1, 2, 3, 4, 6)
paired dorsal aortic artery along pharyngeal arches, but fuse to form the dorsal aorta as a single artery posteriorly
What contibutions do the following aortic arch remnants provide to the circulatory system?
- Dorsal Aortae
- Arch 1
- Arch 2
- Arch 3
- Arch 4
- Arch 5
- Aortic Sac
- Dorsal Aortae
- (1,2,3) part of internal carotid
- lost between 3 and 4
- 4,6 = descendign aorta
- 4 right - portion right subclavian
- Arch 1
- mainly lost (contributes to maxillary artery)
- Arch 2
- mainly lost (contributes to stapedial artery)
- Arch 3
- common carotid and proximal internal carotid
- Arch 4
- right forms right subclavian
- left forms arch of aorta
- Arch 5
- right forms pulmonary artery
- left forms pulmonary artery (proximal)
- left forms ductus arteriosus (distal)
- Aortic Sac
- distal contributes to external carotid
- forms part of brachiocephalic trunk
- forms ascending aorta
What is the definition of cardinal veins?
Describe the cardinal veins
they drain all of the embryo except the digestive system
- anterior cardinal veins
- drain body anterior ot heart, empty into common cardinal vein
- will from the superior vena cava
- posteior cardinal veins
- drain the body posterior to the heart, empty into the common cardinal vein
- later in development, paralled by the subcardinal and supracardinal veins which form the inferior vena cava and the azygous vein
- common cardinal veings
- drain into sinus horns
- anastamosisbetween the right and left anterior cardinals leading to a marked asymmetry in the common caridnals and sinus horns, left reduced
Desribe the path of fetal blood circulation starting with the umbilical vein
- Umbilical vein brings oxygenated blood back from the placenta
- bypasses the liver via ductus venosus
- empty into inferior vena cava
- blood mixes w/ deoxygenated blood
- dump into right atrium, through foramen ovale and into left atrium
- into left ventricle, into the aorta and distributed through the body
What is the relationship between the pulmonary trunk and the ascending aorta?
the pulmonary trunk is most anterior of the great vessels and spirals around the ascending aorta
Where is the fossa ovalis found and what is it a remnant of?
sinus venarum?
wall of right atrium includes the fossa ovalis (remnant of foramen ovale)
low ridge of the crista terminalis forms the border around the smooth-walled sinus venarum (remnant of sinus venosus)
What are the 3 major aorticopulmonary septal defects?
- Transposition of the great vessels
- septum does not spiral
- pulmonary trunk on L ventricle
- aorta on R ventricle
- Persistent Truncus Arterosus
- Septum does not form
- both ventricles open to the same vessel
- Tetralogy of Fallot (most common)
- right ventricular outlow tract obstruction
- right ventricular hypertrophy
- ventricular septal defect
- overriding aorta
What is the conditon that occurs when blood can flow between the atria?
What is the name of the most common type?
atrial septal defects
ostium secundum, where hte septa primum and secundum do not approach each other = large foramen that can’t close
What is the condition where blood can flow between the ventricles?
What is the most common form?
ventricular septal defects
the most common is a membranous septal defect in which the membranous ventricular septum eithe rregresses or simply fails to fuse with either of the bulbar ridge or the interventricular septum
