Cardiovascular system Flashcards
What do angioblastic cords form?
these cords canalize to form small endocardial tubes
Where do angioblastic cords develop?
develop in cardiogenic mesoderm on both sides of embryo in week 3
What is the sinus venosus?
The sinus venosus is a large quadrangular cavity which precedes the atrium on the venous side of the chordate heart. In humans, it exists distinctly only in the embryonic heart, where it is found between the two venae cavae
Where does the sinuatrial orifice slide to?
gradually moves to the right side of the primordial atrium
What happens to the left:
- vitelline vein? - umbilical vein? - common cardinal vein?
- left vitelline vein, umbilical vein and common carinal vein regress
- small portion exists as coronary sinus
The right vitelline vein in the right sinus horn contributes to what?
Inferior vena cava
The right anterior and common cardinal veins in the right sinus horn contribute to what?
Superior vena cava
What is the sinus venarum of right adult atrium?
smooth part of the adult right atrium derived from sinus venosus
What are the pectinate muscles?
- Where are they located?
located in areas of adult atrium derived from primordial atrium
- includes the right auricle - located in the walls of the right atrium
What is the crista terminalis?
Internal ridge demarcating transition between sinus venarum and “atrium”
What is the sulcus terminalis?
external shallow groove demarcating the transition between sinus and “atrium”
Where does the primordial pulmonary vein grow from?
grows as dorsal outgrowth from the dorsal atrial wall just left of septum primum
How many branches does the primordial primary veins develop?
4
Where do the 4 branches (pulmonary veins) get incorporated into?
left atrium
Why is the adult left atrium almost entirely smooth?
represents the incorporation of the pulmonary veins
Where are the pectinate muscles located in the left atrium?
located in areas of the adult atrium derived from primordial atrium
- limited to left auricle
What is the interventricular septum?
begins as median ridge from floor of ventricle near apex
Where does the muscular IV septum grow from?
myoblasts proliferate and grow toward endocardial cushions
Where does the membranous IV septum grow from?
mesenchyme grows from endocardial cushions toward muscular IV septum
Where is the interventricular foramen?
present between free edge of muscular IV septum and endocardial cushions
What causes the interventricular foramen to close in week 7?
when the membranous and muscular IV septa fuse
How do trabeculae carnae develop?
form as the ventricular walls cavitate
How do papillary muscles and chordae tendinae develop?
develop in specific locations
- papillary from myocardium - chordae tendinae from left over connecting tissue of myocardium
How do AV valve membranes develop?
develop from endocardial cushions
How is the single heart tube formed?
folding of the embryo allows for the fusion of the small endocardial tubes to form the heart tube
What day does the heart tube begin beating?
day 22
When can blood flow be detected by ultrasonography?
week 4
What and where is the endocardium?
thin endothelial lining of heart tube in the embryonic heart
What and where is myocardium?
derived from splanchnic mesoderm around the pericardial cavity in the embryonic heart
What and where is cardiac jelly?
gelatinous connective tissue layer between endocardium and myocardium in the embryonic heart
What about epicardium in the embryonic heart?
epicardium will grow from mesothelium later on
Where is the bulbis cordis?
cranial end of heart tube
Where and what is the truncus arteriosus?
contained within the bulbis cordis and is the origin of the arterial tree
- fixed in place by association with pharyngeal arches
When the embryonic heart elongates and develops it develops what dilations and constrictions?
- bulbis cordis
- primordial ventricle
- primordial atrium
- sinus venosus
Where is the sinus venosus?
- what is it?
caudal end of heart tube
- receives the venous return - fixed in place by association with septum transversum
Common cardinal veins return from where?
provide venous return from embryo
Vitelline veins return from where?
provide venous return from umbilical vesicle
Umbilical veins return from where?
provide venous return from placenta
How is blood circulated through the embryonic heart in week 4 and by what means?
- via peristaltic waves
- venous return => sinus venosus which passes through sinuatrial valves => atrium which passes through AV canal => primordial ventricle which is then pumped through bulbis cordis and truncus arteriosus into the aortic sac and distributed into pharyngeal arteries and dorsal aortas
Where does the bulboventricular loop occur?
forms as bulbis cordis and ventricles grow faster than other parts of heart tube
Where does the atrium and sinus venosus end up?
atrium and sinus venosus come to lie dorsally and cranially
Where does the bulbis cordis and ventricle end up?
bulbis cordis and ventricle come to lie ventrally and caudally
Where does the heart bulge into?
the pericardial cavity
What adheres to the heart as it grows?
epicardium (visceral pericardium)
Where is the heart initially suspended?
suspended to dorsal wall of pericardial cavity by dorsal mesocardium
How does the transverse pericardial sinus form?
forms when a gap develops in the degenerating dorsal mesocardium