Term
| earliest sign of heart appearance |
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Definition
| two endothelial lined tubes found cranial and lateral to neural plate |
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Term
| folding of embryo; how? when? |
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Definition
| to bring heart to final location w/in thoracic region; cranio-caudal folding; bw 3-8 wks |
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Term
| heart precursor cells are where? |
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Definition
| w/in primary cardiogenic field |
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Term
| primary cardiogenic field |
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Definition
| horse-shoe shaped zone of splanchnic mesoderm cranial and lateral to neural plate |
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Term
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Definition
| brings endocardial heart tubes into ventral midline where they meet and fuse together into a single definitive heart tube |
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Term
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Definition
| repositions heart tubes into presumptive thoracic region |
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Term
| primitive heart tube; formed how? |
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Definition
| endocardial heart tubes meet and apoptosis occurs midline to give one tube |
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Term
| primitive heart tube; composed of what? |
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Definition
| 1. inner endocardial layer (internal lining of heart chambers) 2. middle layer of cardiac jelly (ECM proteins) 3. outer myocardial layer (heart muscle) 4. mesoderm (forms epicardium) |
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Term
| primitive heart receives what vessels? |
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Definition
| receives 3 paired vessels into inflow portion; 1. vitelline veins (deox from yolk sac) 2. cardinal veins (deox from body of embryo) 3. umbilical veins (ox from placenta) |
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Term
| when does heart start beating? |
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Definition
| at week 3 of embryological development |
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Term
| flow of blood thru primitive heart |
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Definition
| vitelline, cardinal and umbiliical veins enter into atria via sinus venosus to ventricles then leave via outflow tract |
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Term
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Definition
| outflow tract of primitive heart; will divide to form aorta & pulmonary trunk; connects to aortic arch arteries |
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Term
| transverse pericardial sinus |
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Definition
| connects both sides of pericardial cavity; separates the outflow vessels from inflow vessels of heart; forms from degeneration of dorsal mesocardium |
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Term
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Definition
| intial support mechanism for primitive heart tubes |
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Term
| clinical use for transverse pericardial sinus |
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Definition
| postnatally it is an area of pericardial cavity behind aorta and pulmonary trunk and anterior to SVC; clinical: used to clamp off vessels during heart surgery |
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Term
| 5 dilatations of the heart tube |
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Definition
| develop into adult structures of the heart; 1. truncus arteriosus 2. bulbus cordis 3. primitive ventricle 4. primitive atrium 5. sinus venosus (L and R horns) |
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Term
| circulation thru primitive heart |
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Definition
| sinus venosus trhu primitive atrium thru atrioventricular valve to primitive ventricle to bulbus cordis to truncus arteriosus into aortic sac |
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Term
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Definition
| caudal (atrial) portion shifts dorsocranially and to the left; ventricles are moving ventrocaudally and to the right |
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Term
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Definition
| when heart lies on right side of thorax instead of left due to abnormal heart looping |
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Term
| dextrocardia w/ situs inversus; prognosis? |
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Definition
| internal organs are also transposed/inverted; affected individuals can live normal life bc of frequency of accompanying cardiac defects is low |
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Term
| isolated dextrocardia; prognosis? |
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Definition
| usually accompanied by severe cardiac anomalies ex: single ventricle, VSD, persistent left SVC, drainage of great cardiac vein into left thoracic vein |
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Term
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Definition
| 1. original primitive atrium 2. right horn of sinus venosus |
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Term
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Definition
| changes in sinus venosus: left horn becomes insignificant so right horn works harder and enlarges to become posterior wall of right atrium; left to right shunting of blood in venous system; left umbilical vein and left vitelline vein are obliterated; left sinus horn loses function |
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Term
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Definition
| left common cardinal vein is obliterated = remnants of left sinus horn form oblique vein of left atrium and coronary sinus |
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Term
| structure of right atrium |
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Definition
| trabeculated part from original primitive atrium; smooth portion from rigth horn of sinus venosus (AKA sinus venarum); crista terminalis - elevated ridge internally; sulcus terminlais externally |
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Term
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Definition
| pulmonary vein forms from left posterior atrial wall, divides 2x to give 4 veins, grows towards lungs connecting w vessels around bronchial buds; pulmonary vein tissue = smooth region of left atrial wall; primitive atrium forms trabeculated part |
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Term
| circulation thru fetal heart |
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Definition
| 1. ox blood from mom enters RA (shortcircuits lungs bc fetus doesnt breath and blood is already ox) 2. ox blood into LA (thru foramen ovale); small amt of blood is sent to lungs (not shunted) for lung development |
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Term
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Definition
| at end of week 4; 1. septum primum (thin membrane) grows towards endocardial cushions 2. ostium primum is formed (allows ox blood to pass from RA to LA) 3. endocardial cushions grow into AV region 4. apoptosis forms hole in central portion of ostium secundum 5. septum secundum (thick muscular membrane) grows to the right of septum primum overlapping foramen secundum, leaving oval = foramen ovale; septum primum = valve of foramen ovale |
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Term
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Definition
| allows ox blood in RA from IVC and SVC to pass into LA bypassing the lungs; to conserve embryo's strength; closes at birth, closes completely by 6 months to 1 yr of age; fossa ovalis in adult heart |
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Term
| probe patent foramen ovale |
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Definition
| ASD; caused by incomplete fusion of septum primum and septum secundum; in 25% of pop; no clinical importance as blood amt passing from RA to LA is small |
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Term
| premature closure of foramen ovale |
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Definition
| during prenatal life; results in hypertrophy of right heart and underdevelopment of left; death usually after birth (left side too weak to pump blood thru systemic circ efficiently) |
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Term
| bulbis cordis forms what? |
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Definition
| smooth part of right ventricle (conus arteriosus) and left ventricle (aortic vestibule) |
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Term
| truncus arteriosus forms what? |
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Definition
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Term
| primitive atrium forms what? |
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Definition
| trabeculated part of right and left atrium |
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Term
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Definition
smooth part of right atrium (sinus venarum)
coronary sinus
oblique vein of left atrium |
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Term
| primitive ventricles form what? |
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Definition
| trabeculated part of right and left ventricle |
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Term
| interventricular septum (IVS) |
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Definition
| partitions ventricles; formed by two adjoining septa - 1. muscular septum (derived from myocardium) 2. membraneous septum (from fusion of three tissues) |
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Term
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Definition
1. endocardial cushions
2. muscular septum
3. aortico-pulmonary septum
completes separation of ventricles |
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Term
| VSD (ventricular septal defects) |
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Definition
many small VSD close spontaneously
more frequently in males than females
most common part is membranous (70%) - often associated w/ aorticopulmonary septum
forms RV hypertrophy
large VSDs can cause excessive pulmonary blood flow = pulmonary hypertension and cardiac failure in infancy |
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Term
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Definition
less common than membranous
Swiss Cheese VSD - multiple defects; can be corrected surgically; has variations in severity |
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Term
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Definition
| part of bulbic cordis that tapers and merges with truncus arteriosus at its cranial end |
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Term
| AP septum (aorticopulmonary septum) formation |
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Definition
neural crest cells migrate and invade truncal and bulbar ridges that grow and twist around each other in spiral fashion and fuse to form AP septum
shape is influenced by continuous blood flow thru developing heart
AP septum divides truncus arteriosus and conus cordis into aorta and pulmonary trunk
it connects aorta to left ventricle and pulmonary artery to right ventricle |
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Term
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Definition
develop week 5-8
develop from local proliferation of mesenchyme around atrioventricular orifice
free edge of leaflet attached to cordae tendinae (connect to papillary muscles)
valves form cranially and migrate caudally
papillary mm form caudally and migrate cranially |
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Term
| persistent truncus arteriosus |
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Definition
failure to partition truncus arteriosus
ALWAYS associated w/ membranous VSD
results in common outflow channel for both V - cyanosis, fatal if not treated |
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Term
| transposition of great vessels |
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Definition
spiral septum not formed but runs "straight down" = aorta arises from RV and pulmonary artery from LV
incompatible w/ life unless have shunt like VSD, patent foramen ovale or patent ductus arteriosus |
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Term
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Definition
4 abnormalities caused by unequal division of truncus arteriosus caused by anterior displacement of AP septum
1. pulmonary stenosis
2. VSD - membraneous
3. overriding aorta (rightward displacement)
4. RV hypertrophy (caused by higher P on right side)
poor oxygenation, cyanosis
surgically corrected |
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Term
| where does the development of the cardiovascular system start? |
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Definition
| in the mesoderm both w/in the embryo (embryonic) and outside the embryo (extra embryonic) |
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Term
| extra-embryonic mesoderm locations |
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Definition
1. yolk sac
2. connecting stalk
3. chorion |
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Term
| intraembryonic mesoderm location |
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Definition
| splanchnic mesodermal layer |
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Term
| blood islands; formed from what? differentiations? |
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Definition
- specialized mesoderm formed from splanchnic mesodermal layer (intraembryonic mesoderm); differentiates into: 1. angioblasts 2. haemocytoblasts
- formation also happens in extra-embryonic mesoderm (yolk sac, chorion, connecting stalk); 2 sources eventually fuse |
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Term
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Definition
differentiate and give rise to major vessels
ex: aorta via vasculogenesis (by de novo production of endothelial cells) |
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Term
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Definition
formation of branching from major vessels of vascular system
"from pre-existing vessels" |
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Term
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Definition
- formed from blood islands
- form nucleated red blood cells; clinical: can be used to differentiate bw mother and fetus blood (as post-natally RBCs have no nucleus) |
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Term
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Definition
five paired arteries, develop in association w/ pharyngeal/branchial arches; embedded in mesenchyme; develop craniocaudally on R and L sides
numbered 1,2,3,4,6 (no 5)
asymmetrical development |
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Term
| each aortic arch has what? |
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Definition
1. catilagenous component
2. nervous component
3. muscular component
4. arterial component |
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Term
| development of aortic arches |
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Definition
cranially arise from aortic sac, distal part of truncus arteriosus
dorsally connect to L and R aortae |
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Term
| descending aorta formation |
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Definition
dorsal aortae remain separate in region of aortic arches
fuse together from T4 to L4 = descending aorta |
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Term
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Definition
most degenerates
adult remnants: maxillary arteries (in face) |
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Term
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Definition
most degenerates
adult remnants: stapedial arteries (head and neck) |
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Term
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Definition
forms:
1. R and L common carotid arteries
2. internal carotid arteries - majority from 3rd arch, small portion from dorsal aortea
3. external carotid arteries branch off (still debated, unknown origin) |
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Term
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Definition
asymmetrical development
1. left side becomes arch of aorta
2. right side becomes right subclavian artery (proximal segment) |
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Term
| right subclavian artery formation |
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Definition
proximal segment - right side of 4th arotic arch
distal segment - 7th intersegmental artery |
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Term
| intersegmental artery formation |
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Definition
| arise bw somites as small paired branches of dorsal aorta |
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Term
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Definition
1. aortic sac from truncus arteriosus
2. arch of aorta from left side of 4th aortic arch
3. descending aorta from fusion of 2 dorsal aortae at T4-L4 |
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Term
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Definition
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Term
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Definition
also known as pulmonary arch
1. right side proximal portion forms R pulmonary artery; grows towards lungs
2. right side distal portion degenerates
3. left side forms ductus arteriosus (AKA ligamentum arteriosus post-natally) and some of L pulmonary artery |
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Term
| L pulmonary artery formation |
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Definition
some from left side of 6th aortic arch
most from truncus arteriosus |
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Term
| recurrent laryngeal nerves |
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Definition
branches of vagus n (cX)
move cranially w/ larynx
L - loops under L 6th aortic arch - ductus arteriosus
R - loops under R 4th aortic arch - right subclavian artery |
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Term
| coarctation (constriction) of the aorta |
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Definition
in 10% of pop w/ congenital heart disease
constriction of varying length of lumen of aorta BELOW origin of L subclavian artery |
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Term
| preductal coarctation of the aorta |
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Definition
less common
- constriction is above ductus arteriosus (DA)
- patent DA permits continuous blood flow to inferior body, otherwise collateral branches develop to route blood; carries mixed blood = must be corrected surgically
- cause is thought to be abnormality of tunica media and proliferation of tunica intima |
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Term
| postductal coarctation of the aorta |
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Definition
most common
- below ductus arteriosus
- collateral branched develop via intercostal and interal thoracic (mammary) arteries to get blood flow to descending aorta
- collateral branching can form rib notching, caused by dilated intercostal arteries |
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Term
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Definition
- failure of R dorsal aorta to regress = 2 dorsal aortae
- results in vascular ring which can constrict esophagus and trachea
- variations and severity of disease |
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Term
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Definition
- blood vessels of yolk sac
- yolk sac regresses, blood vessels anastamose into vascular plexuses, lose connection to yolk sac and join to dorsal aorta
- adult derivatives: arteries of gut - celiac, superior and inferior mesenteric arteries |
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Term
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Definition
- R and L arise in connecting stalk (future umbilical cord) in week 4 of dev
- lose connection to dorsal aortae in week 5 and connect to common iliac arteries
- post-natally: proximal portions are retained and give rise to internal iliac and superior vesicle arteries; distal portion obliterated to give medial umbilical ligaments |
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Term
| venous system - 3 paired veins |
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Definition
1. vitelline veins drain deox blood from yolk sac
2. umbilical veins return ox blood from placenta
3. common cardinal veins drain deox venous blood from body of embryo |
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Term
| venous system remodeling - vitelline veins |
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Definition
asymmetical development:
- drain yolk sac into R and L sinus horns
- form plexus around duodenum = portal vein (connects to hepatic sinusoids in liver; pass thru septum transversum)
- hepatic veins form from R and L vitelline veins
- R vitelline vein enlarges and becomes R hepatocardiac channel = hepatic portion of IVC
- left proximal vitelline vein regresses |
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Term
| venous system remodeling - umbilical veins |
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Definition
asymmetical development:
- R is completely obliterated during month 2
- distal portions of both connecting to sinus venosus degenerate (umbilical vein will drain into ductus venosus to IVC to RA)
- portion of L umbilical vein remains to carry ox blood from placenta to heart
- ductus venosus forms in liver |
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Term
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Definition
forms in liver
fetal shunt to bypass liver sinusoids; connects hepatocardiac channel w/ left umbilical vein (definitive umbilical vein) |
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Term
| venous system remodeling - cardinal veins |
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Definition
- anterior (drain cranial )and posterior (drain caudal) cardinal veins unite to give common cardinal vein - drain body of embryo
- drain into sinus venosus via common cardinal vein = main venous drainage |
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Term
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Definition
in week 7 other cardinal veins form to drain body wall via intercostal veins, take over for posterior cardinal veins:
1. supracardinal veins drain body wall
2. subcardinal veins drain kidneys
3. sacrocardinal veins drain lower extremities
= will give rise to renal, adrenal, gonadal, azygos, hemiazygos veins and parts of IVC |
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Term
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Definition
consists of:
1. hepatic segment derived from hepatocardiac channel (R vitelline vein)
2. renal segment derived from R subcardinal vein
3. postrenal (sacrocardinal) segment derived from R sacrocardinal vein
- if any are missing can survive by setting up another collateral circulation |
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Term
| superior vena cava formation |
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Definition
| forms from anastomoses bw R common cardinal vein and R anterior cardinal vein |
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Term
| left brachiocephalic vein |
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Definition
functions to shunt systemic blood from L to R side
develops from anastomoses bw L and R anterior cardinal veins |
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Term
| absence of (hepatic segment) of IVC |
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Definition
failure of hepatic segment to form
blood from caudal parts of body drain via azygos and hemiazygos veins (not IVC)
usually associated w/ other heart malformations |
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Term
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Definition
3 shunts:
1. ductus venosus - in liver, blood doesnt need to be detoxified bc mom had already done that; small amt blood flows into liver for its development
2. oval foramen - bw RA and LA
3. ductus ateriosus - bw pulmonary trunk and lungs
* all three shunts must close post-natally |
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Term
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Definition
1. pulmonary and systemic circuits are separate
2. w/ 1st breath alveoli in lung expand causing pulmonary vessels to open and resistance in them to decrease
3. placental blood flow stops
4. opening of pulmonary circulation and cessation of placental blood start circulatory changes ex: closing of shunts |
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Term
| fetal circulation post-natally: ductus ateriosus |
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Definition
1. lung opening and pulmonary vasculature decrease P in pulmonary artery
2. ox blood enters ductus arteriosus
3. localized increase in O2 tension constricts ductus arteriosus
4. occurs immediately after birth
5. complete anatomical obliteration by proliferation of intima take 1-3 months
6. adult derivative = ligamentum arteriosum |
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Term
| fetal circulation post-natally: foramen ovale |
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Definition
1. closure from P changes in atria
2. opening of pulmonary circulation increases P in LA
3. P change forces septum primum against septum secundum = closure
4. cyanotic periods in 1st days of life can occur if baby cries too hard = reversal of closure
5. permanent closure and fusion of septa takes ~ 1 yr
6. adult derivative = oval fossa |
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Term
| fetal circulation post-natally: umbilical arteries |
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Definition
close few mins after birth due to contraction of smooth m in vessel walls
permanent closure by fibrous proliferation takes 2-3 months
adult derivative = medial umbilical ligaments |
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Term
| fetal circulation post-natally: umbilical vein and ductus venosus |
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Definition
umbilical vein closes after umbilical arteries
intra-abdominal portion of umbilical vein = ligamentum teres hepatic (round ligament of liver)
ductus venosus is obliterated; adult derivative = ligamentum venosum |
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