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Embryology - Cardiac Development
Cole 3/7/11 lecture -2hrs
101
Medical
Undergraduate 4
03/07/2011

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Term
cardiovascular system
Definition
first organ system to FUNCTION in the embryo
Term
CNS
Definition
first organ to start developing in the embryo
Term
cardiogenic mesnchyme
Definition
what folds down with the head to form the heart?
Term
Endocardial tubes (2 of them)
Definition
what fuses to form a single heart tube?
Term
sinus venosus (right and left)
Definition
when the endocardial tubes fuse, what is the name of the structure the blood flows in to the heart?
Term
when the heart tube forms at the very beginning
Definition
when do the three layers of the heart form (endocardium, myocardium, epicardium)?
Term
anterior(head) and posterior(below head) cardinal veins that form the common cardinal vein
Definition
how is blood drained from the embryo?
Term
aortic arches that connect to the dorsal aorta which subdivides into smaller vessels
Definition
where do the initial arteries supplying the embryo come from?
Term
the vitelline circuits(yolk sac),
 and the umbillical circuits
(2 arteries with deoxy blood away from fetus, 1 vein with oxy blood from placenta)
Definition
what are the extra embryonic vascular circuits?
Term
vitelline circuit
Definition
what vascular circuit supplies and drains the yolk sac?
Term
the yolk sac
Definition
what acts as a nursery for blood cells?
Term
oxygenated blood from the placenta
Definition
what kind of blood does the umbillical vein carry? from where?
Term
5 weeks
Definition
when does the primitive circulation develop?
Term
1) common cardinal veins
2) umbillical vein (blood from mom)
3) vitelline vein (blood from yolk sac)
Definition
what flows into the sinus venosus
Term
1) sinus venosus
2) primitive atrium
3) primitve ventricle
4) bulbis cordis
5) truncus arteriosus
Definition
list the embryonic heart structures in the order blood flows through them
Term
smooth part of the right atrium (sinus venarum) coronary sinus, and oblique vein of left atrium
Definition
what does the sinus venosus become?
Term
ventricle: trabeculated part of the right and left ventricles
atria: trabeculated part of l and r atria(auricles)
Definition
what does the primitive ventricle become? primitive atria
Term
smooth part of the RIGHT ventricle(conus cordis) and the smooth part of the LEFT ventricle (aortic vestibule)
Definition
what does the bulbus cordis become in the adult?
Term
aorta and pulmonary trunk
Definition
what does the truncus arteriosus become in the adult?
Term
left (aorta on the left)
Definition
on what side is systemic arterial outflow?
Term
right (vena cava on the right)
Definition
on what side is systemic venous return?
Term
it folds and some parts undergo apoptosis
Definition
because the heart needs to grow, and it is limited to a confined space, what does it do?
Term
a structure in the middle of the forming heart that stuff attaches to, and separates the chambers of the heart
Definition
what is the endocardial cushion?
Term
dextral looping
Definition
when the heart begins this process, the aortic arches (arterial end) joins with the septum transversum (venous end)
Term
the truncus arteriosus, bulbus cordis, and ventricle
Definition
what parts of the embryonic heart grow faster causing it to twist and fold?
Term
day 23 ish
Definition
when does the heart start folding up?
Term
posterior
Definition
where is the site of apoptosis as the heart begins folding? (Anterior, posterior, lateral, medial etc)
Term
bulboventricular loop, dorsal folding
Definition
what is it called when the heart bends on itself? what direction does it fold?
Term
dextrocardia
Definition
the heart bends to the left instead of the right
Term
dextrocardia (the heart is displaced to the right with transposition of the heart and great vessels
Definition
what is the most common positional abnormality of the heart?
Term
1 in 8,000 people
Definition
how common is dextrocardia?
Term
because it started forming in the cervical region and migrated down with the diaphragm
Definition
why does the heart have cervical sympathetics?
Term
1) partition of the truncus arteriosus-> semilunar valves
2) and partitioning of the AV canal -> bicuspid/tricuspid valves

(BOTH partition simultaneously)


this partitions the AV canal and the primitive atrium and ventricle
Definition
what is the first partition of the heart?
Term
they are first separated after folding, by the narrow AV canal
Definition
when are the atrium and ventricle first separated and by what structure?
Term
dorsal and ventral blocks of tissue that grow together
Definition
what forms the endocardial cushions?
Term
the AV canals (and their valves)
Definition
what regulates blood flow from atria to ventricles?
Term
formation and fusion of the endocardial cushions
Definition
first step in the development of the 4 chambered heart
Term
atrioventricular communis
Definition
large communication that occurs between chambers that occurs when the cushions fail to fuse
Term
the tissue cannot be adequately prefused most likely because there is mixed arterial and venous blood
Definition
if there is an atrioventricular communis, what problem does the fetus have?
Term
midline on the floor of the primitive ventricle there is an upward growth towards the endocardial cushions and down growing bulbar ridges
Definition
what forms the muscular portion of the IV septum?
Term
ventricular septal defects (VSD's)
Definition
25% of all congenital heart defects
Term
the muscular portion of the septa
Definition
where do most ventricular septal defects occur?
Term
muscular VSD's spontaneously close
membranous defects require surgical repair
Definition
what should be done about a VSD in the muscular portion of the septum? in the membranous portion of the septum?
Term
ventricular septal defects
Definition
opening between left and right ventricles, associated with shunting of blood
Term
There is a foramen primum (original communication between the 2 atria).
1) First there is  a downward growth(septum primum) which stops before hitting the cushions-need a hole
2)Then you punch a hole in the septum primum(foramen secundum)
3) The bottom portion of the septum primum fuses with the endocardial cushion (closing foramen primum)
4) the you form septum secundum by an upper portion growing down, and a lower portion growing up
5) the top of septum secundum meets the top of the remaining septum primum
6) foramen secundum becomes the foramen ovale(the top part of septum primum shrivvels up and dies)
Definition
how does the Atrial septum form?
Term
foramen ovale (aka foramen secundum)
Definition
what is the hole between the septum primum and septum secundum called?
Term
valve of the foramen ovale
Definition
when the septum primum and septum secundum overlap, they form a valve, what is this called?
Term
to bypass the lungs of the fetus
Definition
what is the purpose of the foramen ovale?
Term
right atria
Definition
before birth which atria has higher pressure?
Term
right atria
Definition
after birth, which atria have lower pressure?
Term
atrial septal defects
Definition
defect present in 10-15% of patients with congenital cardiac anomalies
Term
ostium(foramen) primum, secundum, sinus venosus, common atrium
Definition
what are the 4 types of ASD's?
Term
ostium primum defects
Definition
similar to endocardial cushion defects
Term
ostium primum defects (an ASD)
Definition
similar to endocardial cushion defects
Term
secundum type ASD's
Definition
defect involving the foramen ovale and septum primum
Term
right horn, blood is shunted from left to right

(this is a change in the sinus venosum)
Definition
though the horns of the heart start off equal size, one horn of the heart is bigger -which- left or right? why?
Term
the dorsal wall of the primitive atrium
Definition
where does the sinus venosus open initially?
Term
right side
Definition
when the sinus venosus changes, what side does systemic inflow go to?
Term
septum transversum
Definition
where does the liver develop?
Term
they are incorporated into the liver as hepatic sinusoids, hepatic veins, part of the IVC, and some of the veins the drain the GI tract
Definition
what happens to the vitelline veins in the liver?
Term
ligamentum teres hepatis(round ligament)
Definition
when the umbillicle veins lose their direct connection to the heart, what do they become?
Term
the large venous shunt-ductus venosus
Definition
what do the umbillicle veins join when they lose connection to the heart
Term
the umbillical vein and the IVC, bypasses the liver so oxygenated blood is diverted into the heart
Definition
what does the umbillicle shunt connect? what does it bypass?
Term
ductus venosus
Definition
connects umbillicle vein and IVC
Term
bicuspid and tricuspid valves
Definition
what does partitioning of the AV canal form?
Term
pulmonary and semilunar valves
Definition
what does partitioning of th truncus arteriosus form?
Term
IVC
Definition
what structure grows into the right horn of the sinus venosus?
Term
brachiocephalic vein
Definition
what does the anastamosis of the anterior cardinal veins become?
Term
SVC
Definition
what does an anastamosis of the right anterior cardinal and common cardinal vein become?
Term
inferior vena cava
Definition
what do the posterior left and right cardinal veins become?
Term
crista terminalis
Definition
marks division between embryonic sinus venosus and embryonic primitive atrium
Term
neural crest cells
Definition
invades ridges that form in the bulbus cordis and truncus arteriosus
Term
aorta/pulomnary trunk malformations because they are directed by neural crest cell invasion
Definition
what heart disorder accompanies neural crest disorders?
Term
endocardial cushions and IV septum
Definition
what must the distal part of the AP septum(bulbar ridges) contact?
Term
Eisenmenger's Syndrome
Definition
disorder resulting in equal division of truncus but incomplete fusion of bulbar ridges inferiorly -> VSD
Term
Eisnmenger's syndrome
Definition
disorder that starts with an initial L to R shunt, increased pulmonary blood flow, and HTN, later on increased pulmonary resistance caused R->L shunt and cyanosis
Term
1) pulmonary stenosis (unequal division of trunk & aorta)
2) VSD
3) overriding aorta
4) right ventricular hypertrophy (due to resistance in lung)
Definition
name the 4 features of a Tetralogy of Fallot:
Term
arterial switch operation (the aorta and pulmonary artery are "switched")
Definition
what can be done to fix transposition of the great vessels?
Term
6 pairs (12 total)
Definition
how many pairs of aortic arches are there to start with?
Term
aortic sac (truncus arteriosus) and dorsal aorta
Definition
what do aortic arches connect?
Term
1-3 (pharyngeal arches)
Definition
what arches organize the development of the head and neck?
Term
an artery, a cranial nerve, muscle, and sensory fibers
Definition
what accompanies each aortic arch?
Term
on th left it connects the ventral and dorsal aorta (aortic arch)

on the right it forms the subclavian artery
Definition
what does aortic arch IV do?
Term
proximal portions = l & r pulmonary arteries (PULMONARY TRUNK)

distal portion of left aortic arch = ductus arteriosus
Definition
what does aortic arch VI do?
Term
nothing, doesn't become any known vessels
Definition
what does aortic arch V do?
Term
a connection between the pulmonary trunk and aortic arch (a shunt in the lungs good for the baby, but not for an adult)
Definition
what is a patent ductus arteriosus?
Term
hormones and pressure change at birth
Definition
what makes the ductus arteriosus close?
Term
infant: use a ligature to lasso it shut
older child: used a coil to expand it so there is tissue to seal it shut with, then close it off.
Definition
how is a patent ductus arteriosus repaired in an infant? in an older child?
Term
1) cervical segmentals -> vertebral arteries
2) 7th intersegmentals -> subclavian
3) thoracic intersegmentals -> intercostal arteries
4) lumbar intersegmentals -> iliac arteries
Definition
list the dorsal segmental paired branches of the aorta (embryonic, and adult)
Term
20 pairs of vessels supplying the developing kidneys -> adrenal, renal, & gonadal arteries
Definition
what do the lateral segmental branches of the aorta become?
Term
vitelline vessels -> celiac + superior & inferior mesenteric arteries
*reprogrammed from veins to arteries

allantoic vessels -> umbillical arteries
Definition
what are the ventral segmental branches of the aorta, and what do they become?
Term
portion of the IVC, hepatic veins/sinusoids, ductus venosus, portal, superior/inferior mesenteric & splenic veins
Definition
what venous structures do the embryonic vitelline vessels become in the adult?
Term
NOT umbillical arteries!!! that's allantoic vessels of the ventral aorta segments


the umbillical veins collapse and become the ligamentum teres hepatis
Definition
what do the umbillical veins in the fetus become?
Term
anterior: SVC, internal jugulars
posterior: part of IVC, common iliac veins
Definition
what do the anterior and posterior embryonic cardinal veins become in the adult?
Term
independently as an outgrowth of the lung, they are not remade from other vessels
Definition
how do the pulmonary veins form?
Term
left atrium
Definition
venous drainage channels from the lungs converge and form a single vessel that goes where?
Term
lung tissue forming the pulmonary veins
Definition
what tissue helps the atrium expand?
Term
1) Vena cava (common) duplicated or left instead of right
2)PDA
3) double aortic arch
4) right aortic arch
5) coarctation of the aorta
Definition
list the malformations of major blood vessels
Term
right aortic arch
Definition
persistence of the right 4th arch distal to the right subclavian, and the left segment caudal to the subclavian disappears, may be caused by situs inversus
Term
double aortic arch
Definition
segment of the right 4th aortic arch CAUDAL to the right subclavian persists, vascular ring around the trachea and esophagus
Term
coarctation of the aorta
Definition
occurs distal to the left subclavian, typically near the ductus arteriosus (post ductul = adult, preductal = iinfantile)
-collateral circulation often includes the internal thoracic arteries & its branches
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