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49 Cards in this Set
- Front
- Back
when does the cardiovascular system begin to develop?
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week 3
mesenchymal cells derived from mesoderm form endothelial tubes which join to form primitive vascular system |
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from what does the heart develop?
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splanchnic mesenchyme in cardiogenic area
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what forms the paired endocardial heart tubes?
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bilateral cardiogenic cords formed from mesenchyme, which become canalized and then fuse into a single heart tube
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what happens to the mesenchyme surrounding the cardiogenic cords?
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surrounding mesenchyme thickens to form myoepicardial mantle separated from endothelial heart tube by gelatinous cardiac jelly
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what are the four parts of the primitive heart?
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sinus venosus
atrium ventricle bulbus cordis |
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what veins drain into the sinus venosus in the primitive heart?
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vitelline veins from the yolk sac
umbilical veins from the chorion common cardinal veins from the embryo |
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with what is the truncus arteriosus continuous caudally? cranially?
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caudally - bulbus cordis
cranially - enlarges to form aortic sac (from which aortic arches arise) |
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what do the systems of paired veins become after birth?
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vitelline system - portal system
cardinal system - caval system umbilical system - degenerates |
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why does the bulboventricular loop form?
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bulbus cordis and ventricle grow faster than the rest of the heart and it bends on itself to form the bulboventricular loop
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what happens at the same time that the bulboventricular loop forms?
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heart invaginates into pericardial cavity
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what forms the transverse pericardial sinus?
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dorsal mesocardium (which attaches heart to dorsal wall of pericardial cavity) degenerates to form the transverse pericardial sinus
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when does the first heartbeat occur?
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21 to 22 days
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where do the peristalsis-like waves of the primordial heart begin?
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sinus venosus
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when does the heart have coordinated contractions which result in unidirectional flow?
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by the end of week 4
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what is the pathway through the primitive heart?
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blood enters the sinus venosus from vitelline, cardinal, and umbilical veins
blood flows into primitive ventricle ventricular contraction pushes blood into the bulbus cordis and truncus arteriosus into the aortic sac, passing the aortic arches and branchial arches blood passes to dorsal aortae for distribution to embryo, yolk sac and placenta |
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when does the heart divide into four chambers?
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between weeks 4 and 7
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what divides the atrioventricular canal?
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endocardial cushions from the dorsal and ventral walls and begin approaching each other at week 5, fusing, and dividing the atrioventricular canal into right and left canals
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when does the septum primum begin to extend into the atrium? from where?
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day 28
superoposterior wall, growing caudally toward atrioventricular canal |
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when are the left and right atria separated by the septum primum?
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fifth week
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what is the ostium primum?
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foramen that forms in the septum primum
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when does the septum primum fuse with the endocardial cushions to obliterate the ostium primum?
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at the end of the sixth week
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what is the ostium secundum?
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shunt formed by the coalescence of perforations in the septum primum, which form before the ostium primum closes
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what is the septum secundum?
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a flap growing from the roof of the right atrium, but not reaching the endocardial cushion, leaving an opening called the foramen ovale
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what are the two staggered openings through which blood shunting from right atrium to left atrium passes?
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foramen ovale (from septum secundum)
foramen secundum (septum primum) |
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what closes the foramen ovale after birth?
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fusion of the septum primum with the septum secundum
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from where is the coronary sinus derived?
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left horn of the sinus venosus
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from where is the right atrium derived?
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smooth part (sinus venarum) - right horn of the sinus venosus
muscular part (auricle) - primitive atrium |
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what separates the sinus venarum from the auricle internally and externally?
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internally - crista terminalis
externally - sulcus terminalis |
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until when is the crescentic fold which partitions the ventricles open cranially (interventricular foramen)?
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until end of week 7
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when does the aorticopulmonary septum divide the truncus arteriosus into the pulmonary trunk and aorta?
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during week 5
valves develop from proliferation of subendocardial tissue |
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from what temporary pacemaker does the sinus venosus take over?
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primitive atrium
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when does the sinoatrial node develop? from where?
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week 5
(part of the sinus venosus which becomes incorporated into the right atrium) |
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from where does the atrioventricular node develop?
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sinus venosus
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when is the critical period of heart development?
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20-50 days after fertilization
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what is the most common defect of the cardiac septa?
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ventricular septal defects
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what is a membranous ventricular septal defect?
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oval membranous portion of interventricular septum fails to develop
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what is a muscular septal defect?
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perforation anywhere in the muscular part of the interventricular septum
caused by excessive resorption of myocardial tissue during formation of muscular part of interventricular septum |
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what is cor triloculare biatriatum?
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3-chambered heart resulting from absence of interventricular septum
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what does tetralogy of fallot consist of?
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pulmonary valve stenosis
ventricular septal defect overriding aorta hypertrophy of right ventricle (cyanosis is obvious sign but may not be present at birth) |
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what is pulmonary valve stenosis?
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cusps of pulmonary valve are fused together to form a dome with a narrow central opening
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when do aortic arches, arising from the aortic sac, penetrate the branchial arches?
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week 4 and 5
(when the branchial arches form) |
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when is the primitive aortic arch pattern transformed into the adult arterial arrangement?
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during week 6 to 8
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when does the lymphatic system begin to develop?
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week 5
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how does the lymphatic system develop?
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6 primary lymph sacs develop, and later become interconnected by lymph vessels
lymph nodules don't appear until just before and/or after birth |
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what is a hygroma?
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tumor-like mass of dilated lymphatic vessels derived from pinched-off portion of jugular lymph sac
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via what vein does oxygenated blood return to the fetus from the placenta?
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umbilical vein
drains into liver or passes by via ductus venosus |
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what forms a shunt for oxygenated blood to bypass the liver?
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ductus venosus
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what structures of the fetal heart close after birth?
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foramen ovale
ductus arteriosus ductus venosus umbilical vessels |
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how long does it take for left ventricular wall to be thicker than right?
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1 month after birth
(at birth right ventricular wall is thicker) |