CV and RESP system Flashcards
how does the early embryo access nutrients and oxygen and get rid of waste products?
through placenta
what does the heart form from?
from mesoderm around 18 to 19 days after fertilisation
3 germ layers of heart are?
ectoderm (top)
mesoderm (middle)
endoderm (bottom)
cardiogenic area or plate?
within mesoderm, a horseshoe-shaped area develops
where does the cardiogenic plate move to?
moves ventral to the pharynx as the head process grows upward and outward
what is the cardiogenic plate formed from?
from cardiac myoblasts and blood islands (forerunners of blood cells and vessels)
within each side of the cardiogenic area, what forms?
an endocardial tube forms (lined by endothelial cells)
where do the endocardial tubes fuse?
they fuse midway along their length, forming the tubular heart or cardiac tube
a single tube is formed with an arterial and a venous end
atria are the?
blood receiving chambers
ventricles are the?
blood pumping chambers
what is the auricle?
it is the blind ear-shaped pouch of the atrium
as endocardial tube lengthens, what happens?
it loops on itself
this puts the bulbus cordis (right ventricle) beside the ventricle (left) and the atrium dorsal to the ventricle
what happens to the venous return during morphogenesis?
it is shifted to the right
the larger right sinus venosus becomes the right atrium (embryonic atrium becomes auricles)
the smaller left sinus venosus joins the future right atrium as the coronary sinus venosus
describe the formation of cardiac chambers:
partitions form a 4-chambered organ. The septa that form:
divide the atrium and ventricle (cardiac cushions/septum intermedium)
divide the atrium (septum primum and secundum)
divide the ventricle (interventricular septum)
divide the outflow tracts (aortico-pulmonary septum)
Why is it relevant that the foramen secundum forms BEFORE the foramen primum
closes?
so we can create valve
you have two septums
formation of aorta and pulmonary valves:
form from swellings of sub-endothelial mesenchymal tissue
then remodelled to form thin walled cusps
formation of the A-V valves?
form from the proliferation of mesenchymal tissue at the rim of the AV opening, attached to the myocardium
valves remodeled, but remain anchored by muscular strands to the ventricular walls
formation of blood vessels: how many stages?
2 stages
what are the two stages for the formation of the blood vessels?
vasculogenesis and angiogenesis
vasculogenesis?
formation of blood vessels form blood islands
vessel formation happens when island vesicles coalesce, sprout buds and fuse to form vascular channels
angiogenesis?
budding of new vessels from existing vessels
begins with blood island formation in splanchnic mesoderm of the yolk sac and allantois
formation of aortic arches?
bilaterally, ventral & dorsal aortae are connected by up to six aortic arches
what is the first aortic arch?
the cranial fusion between dorsal aortae and cardiac tubes becomes the 1st aortic arches
in total - 6 pairs of aortic arches will develop
what does the aortic arch give rise to?
gives rise to major vascular structures