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71 Cards in this Set
- Front
- Back
When does heart first develop / first function
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middle of third week, functions at beginning 4th week
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why early heart development nec
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repidly growing embryo cant satisfy nutritional requirements via diffusion anymore needs efficient method of acquiring oxygen & nutrients from maternal blood, & disposing of CO2 and waste
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Cardiovascular system derived mainly from
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splanchnic mesoderm (forms primordium of heart), paraxial and lateral mesoderm midway along hindbrain, & neural crest cells from between otic vessicles (primitive ears) and 3rd pair of somites
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differentiation of blood early on?
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none same both into and out of heart tube.
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which three veins drain into the tubular 4th week heart
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vitelline veins with poorly oxygenated blood from yolk sac, umbilical veins with well oxygenated blood from primordial placenta, and common cardinal veins returning poorly oxygenated blood from embryo body
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what does the yolk stalk connect?
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narrow tube between yolk sac and midgut
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describe the early heart tube
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polar, with a venous pole and an arterial pole. Heart tube has an outer myocardial muscular wall that secretes cardiac jelly which deforms when muscle contracts the inner layer is bounded by endocardium lumen there is no outer epicardium
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early heart tube works how?
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myocardium contracts, squeezes jelly, compresses lumen to move blood
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shape changes in heart caused by?
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interaction between jelly and myocardium
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in early heart tube, name chambers from caudally cranially
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sinus venosus (left and right horns, immediately above the 3 pairs of veins coming into heart tube), primitive atria, atrioventricular canal, primitive ventricle, ventricobulbar foramen, bulbus, bulbotruncal junction, truncus
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what arises from the truncus
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the aortic sac, which becomes the aortic arch
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why does heart tube twist?
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bulbus cordis and ventricle grow faster than other regions
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what do the bulbus and ventricle first form
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bulbo-ventricular loop
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what occurs as a result of bending of the heart?
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atrium and sinus venosus become dorsal to truncus arteriosus, bulbus cordis and ventricle
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in the primitive heart, what is the future site of the AV valves?
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atrioventricular canal
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in the primitive heart, what is the future site of the Semilunar valves?
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bulbo-truncal junction
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review veins cardinal veins drain what
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blood from embryo
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review veins umbilicus drains what
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placenta
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review veins- vitelline drains what
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yolk sac
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of the two vitelline veins, which one persists?
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right
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when the superior cardinal veins anastamose, what do they become?
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right cardinal becomes SVC, superior anastamoses between the two becomes the left brachiocephalic
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what happens to the left cardinal vein
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disappears
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how does the sinoatrial orifice shift rightwards
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shunting of blood to right causes it to move until it only communicates with right atrium
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what does the right cardinal vein become
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superior vena cava
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what does the right vitelline vein become
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inferior vena cava
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what happens to the right umbilical vein?
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obliterated
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by what day does the heart start beating
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22
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of vitelline veins, which persists?
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right
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what forms the left ventricle
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primitive ventricle
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forms right ventricle
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bulbus
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what happens with veins near heart?
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right sided veins persist, left sided veins disappear
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right atrium comes from what?
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sinus venosus (smooth) and primitive atrium (which is why right atrium has dual texture
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which part of left atrium is formed by the primitive atrium
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auricle (appendage)
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what appears between the left sinus horn and septum primum
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primary pulmonary vein
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how does left atrium form
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first sign of left atrium is appearance of primary pulmonary vein, which grows toward, and cannibalizes walls of pulmonary veins, absorbing them to create its walls
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what does the atrioventricular canal form
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tricuspid and mitral valves
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name of first septum to grow, and first opening init
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septum primum and foramen primum
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name of second opening, in which septum
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foramen secondum in septum primum, as foramen primum is closing
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septum primum is _______ than secondum
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thinner, more membranous
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where is the foramen ovalis located
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posterior inferior wall of septum secondum
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where does the majority of blood entering the fetal heart come from
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placenta via the umbilical vein 70%
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what supplies the second greatest amount of blood to the fetal heart?
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superior vena cava, from head and arms (about 20%
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how much blood does the heart receive itself?
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about 3%
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where does most of the blood leaving fetal heart go?
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out pulmonary trunk, via ductus, to descending aorta 70%
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what percentage of blood leaving the left bentricle goes to the head?
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about 20%
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how much blood leaving the heart goes out the aortic arch?
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about 10% (remember, 60% or so is going out the pulmonary trunk, joining the 10% from the aortic arch, to go to abdomen and legs)
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what is the percentage of blood going to L&R heart from IVC?
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of the 70% coming into heart from IVC, 44% is going to the right side of the heart, 26% to the left side
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how much blood goes to the heart itself and the lungs
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very little 3% to coronary circulation, about 7% to lungs
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In addition to growth of muscular septum superiorly to separate ventricles, what other mechanism exists
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downward growth of ventricles leaving muscular septum
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what divides the truncus into the aorta & pulm. trunk
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aorticopulmonary septum: (truncal bulbar cushions)
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what closes off the interventricular muscular septum
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the inferior portion of the aorticopulmonary septum
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what is the upper portion of the interventricular septum
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membranous septum
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where is bundle of HIS
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in membranous part of interventricular septum
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what happens if there is a ventricular septal defect
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can put patch over it but have to be careful not to stitch through bundle of HIS
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what are the most common defects of the heart
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membranous
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what is fallots teratology?
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pulmonary stenosis, interventricular communication, hypertrophy of right ventricle causes cyanosis (venous blood in systemic system) and dyspnea (problems breathing)
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cure for fallots teratology
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blalock-taussig shunt connect Left subclavian to pulmonary trunk (more blood to lung, collateral circ. serves arm)
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Before birth all shunts are
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right to left
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blood shunts in one direction why
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higher resistance oon pulmonary side pulmonary arterioles tightly constricted lungs not working yet. lower resistance on aortic-systemic side
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what types of midline defects can occur in fetal heart
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atrial septal, ventricular septal, persisting ductus arteriosus
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what if shunts persist?
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more blood goes to lungs puts additional pressure on lungs, causes lung tissue to thicken irreversibly.
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if pulmonary resistance keeps rising, what happens?
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eventually will reach point that heart wont be able to overcome the resistance
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transposition of great arteries consequences and fix
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blue baby insert atrial septal defect to cause lots of blood mixing in heart repair properly when baby older.
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aortic atresia and left ventricular hypoplasia meaning, consequences, fix.
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no way out of aorta, left ventricle very small, unable to pump. Usually causes death. cure= heart transplant
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morphologic right sided heart characteristics (no matter where actually appears)
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SA node, sinus venosus, primitive atrium
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right heart morphology ventricle
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moderator band
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segmental analysis of chambers look at:
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appendage shape of atria, SA node? pulmonary veins?, ventricular trabeculae, moderator band, continuity (or not) of valves, great arteries: aorta-coronary arteries
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what do lungs and heart have in common?
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whatever atria do, lungs also do: eg: left type atria on right side, will be a left type lung.
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situs ambiguous
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two left atria, two left type lungs
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situs inversus
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sides switched
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if ventricles match atrial type or not = atrioventricular ?
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matches = concordance, doesnt = discordance
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