Heart development Flashcards
where are the cardiac progenitor cells derived from?
intra-embryonic mesoderm
splanchopleuric
what forms in the splanchnic mesoderm?
a horseshoe shape develops as the cariogenic region
on either side of the neural plate
what happens on day 19?
the endocardial tubes begin to develop on each side and grow
what happens to the two endocardial tubes?
lateral folding results in the merging of the two tubes to form the primitive heart
pushed into the thoracic cavity
five distinct regions of primitive heart tube from head to tail
trunks arteriosus, conus cordis, primitive ventricle, primitive atrium and sinus venosus
what will the truncus arteriosus form?
aorta and pulmonary artery
bulbus cordis structures
right ventricle
primitive ventricle will form
the left ventricle
primitive atrium will form
front parts of the left and right atria
what will the sinus venous form?
posterior part of the right atrium, SAN and coronary sinus
at what day does the heart begin contracting ?
22
where does the blood pump?
initially all venous blood moves into the sinus venous and then to the truncus arteriosus
how does the heart tube position change?
- begins in the cariogenic area in front of the oropharyngeal membrane and neural plate
- growth of brain pushes the heart into the chest
what keeps the heart in the right position?
mesodermal tissue fold called the dorsal mesoderm
initial tissues of gut tube
myocardium thickens and secretes a thick layer of rich extracellular matrix called cardiac jelly which separates the endothelium
mesothelial cells from pericardium migrate to form the epicardium
heart tube formed with inner endocardium lining and outer myocardial epicardium
what happens at day 23?
cardiac looping begins
explain looping
bulbs cordis moves ventrally and caudally and to the right
primitive ventricle moves dorsally, cranially and to the left
what happens to the atria?
left sinus horn recedes to form coronary sinus into the right atria
enlarged right sinus horn is absorbed by the growing right atrium and eventually forms part of the inferior vena cava
left atria combine with pulmonary veins
what forms the aortal arch arteries?
branchial arch blood vessels
which arches form the aorta?
3,4 and 6
aortic arches definition
six paired embryological vascular structures that give rise to the great arteries of the neck and head
ventral to the dorsal aorta
different parts of the aorta + what form it
ascending- truncus arteriosios
arch- ventral aorta
dorsal aortae- descending aorta
what does the first heart field form?
everything below the truncus arteriosus
what does the second heart field form?
truncus arterioosis, left ventricle
what process occurs next?
septation of right and left channels
what tissue is formed?
cushion tissue
explain formation of cushion tissue
- endocardium balloons, due to cardiac jelly secretion
- endocardium undergoes EMT and enters the ECM
- superior and inferior cushions fuse, separating the left and right atrioventricular canals
what does the endocardial cushion form?
tricuspid valve, mitral valve, part of atrial septum, part of ventricular septum
how many holes in primitive atria?
3
explain septation of atria
- septum premium forms and extends down towards the fused cushions, splitting the atrium into two
- ostium primum is a hole present between the cushion and septum premium that remains before complete cushion
- ostium secundum forms in the septum primum before premium’s fashion
- septum secundum grows with a hole called the foramen ovale
what does the ostium secundum and foramen ovale allow?
shunt going from right to left
difference in structure of septum secundum and primum
primum- thinner
secundum- thicker more msucular
what does the foramen ovale form?
fossa ovalis in right atrium
where is pressure higher to allow blood to flow?
higher in right than left
allows the shunt to keep going
separation of ventricles
muscular ventricular septum grows from the base of the heart towards the endocardial cushions
sculpted by the blood flowing through the ventricles
membranous septum grows from endocardial cushions and fuse in the middle
different structures in ventricles and how they’re formed
inter ventricular foramina
myocardium thickens to form trabeculae
formation of outflow tract
the truncus arteriosus contains endocardial cushions that grow towards each other
twist and form a spiral septum
dividing outflow tract into the left and right sides, aorta and pulmonary artery respectively
major birth defect
tetralogy of fallot
four defects of tetralogy of fallot
four defects:
1. pulmonary stenosis
- ventricular septal defect
- right ventricular hypertrophy
- overriding aorta
what causes the tetralogy of fallot?
unequal growth of aorticopulmonary septsm
explain tetralogy of fallot
aorta too large
thus steals from pulmonary artery, therefore stenosed
prevents ventricular wall closure, thus septal defect
increases pressure on right side, thus right ventricle is larger to handle work
what happens to the blood that does not pass through the foramen ovale?
- enters pulmonary trunk which is linked to distal arch of aorta by ductus arteriosus
how does blood bypass liver?
ductus venosus
shunts umbilical blood directly into vena cava
what happens at birth?
intake of air, leads pulmonary resistance to fall
pressure in left atrium now higher than right
coses foramen ovale- fuses shut by 11 years
ductus arteriosus contracts to close after birth
structure that remains of ductus arteriosus
ligamento arteiosum
prior to separation, where does venous blood prefer to enter
through vitelline, cardinal and umbilical vein
into the right sinus horn
