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19 Cards in this Set
- Front
- Back
what are the 4 major steps in heart development |
1. cardiac crescent formation 2. linear heart tube formation 3. looping of the tube 4. remodelling |
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what are the 3 cell lines that develop the heart and their derivatives
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1. first heart field: primitive heart tube, forms left and right atria, left ventricle
2. second heart field: anterior- right ventricle and cardiac outflow tract posterior- atrial and atrioventricular septation, systemic and pulmonary veins to atria 3. neural crest cells: conotruncal division and aortic arch formation (extracardiac cells) |
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what are the two types of folding that occur |
1. lateral folding: forming heart tubes to midline to fuse into single tube (~day 20) 2. cranio-caudal folding: heart tube positioned with inflow toward tail (atria and veins) and outflow at head |
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what day does the heartbeat begin? |
~22nd day** |
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define the dorsal mesocardium |
connective tissue sling suspending the heart from the body wall |
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what are the basic components of the heart tube |
top to bottom aortic sac (aortic arches) bulbus cordis (right ventricle, part of outflow tract) primitive ventricle (left ventricle) primitive atrium (part of right and left atrium) sinus venosus (superior vena cava, right atrium) |
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describe the sequence of events in heart looping |
1. straight tube bends ventrally 2. C-shaped loop (ventral bend to the right) 3. S-shaped loop (atrium brought cranially, bend with sinus venosus, bend between bulbus cordis and ventricle) 4. bulbus cordis and arterial trunk move ventral |
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define endocardial cushions |
cells from dorsal and ventral walls of heart grow in between primitive atrium and ventricle forming protrusions fuse to form left and right atrioventricular canals |
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describe the process of inter-atrial septum development |
week 4-5 septum primum develops ostium primum (hole down by endocardial cushion), closes ostium secundum forms in upper septum primum septum secundum forms with foramen ovale ** septum primum becomes thin flap over FO |
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describe the process of interventricular partitioning |
week 6 pimordial muscular ridge in floor of ventricle medial walls fuse into interventricular septum (muscular and membranous) |
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what is a potential effect of maternal diabetes |
week 5 neural crest cells migrate to develop aortic arch impeding neural crest cells from migrating to and affecting the development of the aortic arch single outflow tube? |
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describe the development of the aorta and pulmonary trunk |
small ridges form inside the bulbus cordis and truncus arteriosus fuse and create a spiral shaped septum separating the trunk into aorta and PT cusps derive from bulbar ridges |
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describe AV valve development |
5-8th week left: anterior and posterior (bicuspid/mitral) right: a, p and septal (tricuspid) chordae tendonae and papillary muscles |
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describe the development of the conduction system |
cardiomyocytes in caudal heart tube become electrically active and become pacemaker SA node (5th week) develops in sinus venosus and moves into RA AV node superior to endocardial cushions nodes: slow conducting myocardium of inflow tract bundles: fast conducting ventricular myocardium |
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describe the development of the aortic arch |
6 paired sets of arches form from about week 4-7 neural crest cells aid in development of aortic sac 3rd arch: common and internal carotid arteries bilateraly 4th arch: aortic arch ** 6th arch: right and left pulmonary arteries and ductus arteriosus right arch eventually disappears |
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what are the 3 components of the aortic arch in development |
1. proximal: brachiocephalic to left common carotid artery (aortic sac) 2. distal: left common carotid to left subclavean (4th arch) 3. isthmus: left subclavean to dorsal aorta (4th and 6th arch) |
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describe fetal circulation |
2 arteries and 1 vein inside umbillical cord to placenta vein is oxygenated** enters liver (70% L 30% H, ductus venosus) IVC, RA, FO, LA, LV, aorta, body, umbillical artery some RV, ductus arteriosus to aorta very little to lungs |
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why can congenital heart deformities still result in normally developing babies? |
parallel ventricle system, blood flow is special complete left to right heart obstruction does not impede aortic blood flow foramen ovale and ductus arteriosus provide alternate pathways (until term!) |
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what are the major differences between pre and post natal circulation |
prenatal: right side pressure higher, high pulmonary resistance, 3 shunts, placenta provides O2, IVC has O2 blood, SVC and CS is O2 poor postnatal: lungs inflate, lower pulmonary resistance/rt heart pressure, lt heart pressure rises and FO closes, ductus arteriosus closes within 48-72 hrs, ductus venosus closes, both become ligamentum |