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54 Cards in this Set
- Front
- Back
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What is the first system to become functional during development? Other basic functional issues.
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-Cardiovascular system
-Heart tube formed and beating to propel blood around a closed circulatory system by the end of WEEK 4 (of 38 weeks after fertilization-40 weeks from LMP) -At 4 weeks, there is essentially no pulmonary function, no GI function, no renal function, and only the most rudimentary nervous system, while CV function is EXTENSIVE |
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Embryological Origins of Heart - derived from what,
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-Heart, and rest of cardiovascular system, as well as blood and bone marrow are all derived from MESODERM
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What does mesoderm form (2), what do mesenchymal cells arrange themselves in, which then become precursors of what?
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-Mesoderm form mesenchyme, undifferentiated embryonic CT, rich in mesenchymal fibroblasts
-Mesenchymal cells spontaneously arrange themselves into epithelial vesicles called Angiogenetic Cell Clusters, which then fuse to form tubes, precursors of heart and blood vessels |
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What do the cells in the walls of angiogenetic cell clusters form (1) and where does this process occur, eventually forming what?
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-Cells in walls of angiogenetic cell clusters form fetal RBCs, nucleated at first.
-Process occurs in embryonic body, yolk sac, connecting stalk, and developing placenta, eventually forming a complete, closed circulatory system. |
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Early Heart Formation - what 2 things form the heart tube, then what does this tube do/forms what
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-Blood islands (form endothelium) and myoblasts (form wall of heart) on lateral flanks of neural plate form precursor of heart, two tubes, which migrate ventrally and fuse to form a simple, midline, Ventral Heart Tube.
Heart tube begins to contract, from caudal to cranial, forming a simple mechanical pump, pushing blood from the placenta, through the head, to the rest of the body |
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Fetal Respiration - what happens in placenta? when do lungs inflate and become perfused with fetal blood?
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-Placenta is where oxygenated blood from mother oxygenates fetal blood
-Lungs are not functionally mature until late in pregnancy -Lungs not inflated and not perfused with fetal blood via pulmonary circuit until birth |
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Basic Structure of CV System (3 layers)
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-Heart is really a highly modified blood vessel with Myocardium (homologous to tunica media) containing cardiac muscle instead of smooth muscle
Heart has an Epicardium (tunica adventitia) and Endocardium (tinic intima) |
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Early Heart Formation - what does the Primitive Heart have and not have
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Primitive Heart is a simple tubular dilation of CV system with cardiac muscle cells in wall.
Does not have four chambers |
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Early Heart Formation - heart oriented which way, location of afferents and efferents (each equivalent to what)
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Early heart oriented in opposite direction of grown heart
-Efferents (equivalent to ventricles) located cranially -Afferents (equivalent to atria) located caudally |
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Formation of Cardiac Loop - which way to the cephalic and caudal portions bend, Cardiac relations approach normal except for...
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-Cephalic (ventricular) portion bends ventrally, caudally, and toward right
-Caudal (atrial) portion bends dorsally, cranially, and toward left -Cardiac relations approach normal except for Septation of Atria and Ventricles, which is initially incomplete |
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Septation - atria divided by what (type of valve), when is normal atrial septation completed?, when is ventricular septation complete?
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-Atria divided by a double flap-like curtain of tissue that serves as a ONE WAY VALVE
-One way valve works until birth, thus normally atrial septation not completed until AFTER BIRTH -Ventricular septation complete well before birth |
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What dumps deoxygenated blood into the right atrium?
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IVC dumps deoxygenated blood into the right atrium
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What prevents blood from entering lung and how?
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Do not want to put blood into the lungs (uninflated) and so the Ductus Arteriosus shunts blood from pulmonary trunk out of right ventricle into the aorta instead
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What also bypasses the portal (liver) circulation?
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Ductus Venosus
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What is the fossa ovalis called when it is closed?
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Foramen Ovale
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Atrial septation I - where does Septum primum grow and what is the hole formed in it?
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Septum Primum grows from top of heart toward endocardial cushions- hole forms called Ostium Primum
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Atrial septation I - How does the ostium secundum form?
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As ostium primum is obliterated by growth of septum primum, a second ostium secundum forms before closure of ostium primum
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Atrial septation I - Where does the Septum secundum grow and fuse with, what is the name of the resulting hole formed?
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Septum Secundum grows down over ostium secundum and fuses with endocardial cushions, leaving a hole called Foramen Ovale
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Atrial septation I - What type of valve is formed from all of this? Blood returns to what part of heart and then goes where?
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This creates a One-Way Valve allowing blood flow from high pressure right atrium to low pressure left atrium.
Blood returns to right atrium, passes through foramen ovale, between septum primum and secundum, and enters the left atrium through the ostium secundum |
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Atrial septation II - one-way valve allows passage of blood until when
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-One way valve allows passage of blood from RA to LA up to birth
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Atrial septation II - what happens at birth due to clamping of umbilical cord?
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-At birth, with clamping umbilical cord, pressure in RA decreases and pressure in LA increases, because of sudden pulmonary perfusion. This pressure differential closes atrial septum
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Atrial septation II - what happens after birth with septum primum and secundum?
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-After birth, septum primum and septum secundum fuse, obliterating foramen ovale and ostium secundum, so that RA and LA are separated
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Septatation of Ventricles - Most of Interventricular Septum (IVS) forms from Growth of and fusion of...
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Most of Interventricular Septum (IVS) forms from Growth of Ventricular Walls and secondary fusion of walls to form the Muscular Portion of the IVS
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Top part of IVS forms from..., which forms what as a whole
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Top part of IVS forms from inferior endocardial cushion. This forms membranous portion of IVS
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What types of circulation are the left and right ventricle involved in (1 each)
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Left ventricle: systemic circulation
Right ventricle: pulmonary circulation |
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What dumps deoxygenated blood into the right atrium?
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IVC dumps deoxygenated blood into the right atrium
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What prevents blood from entering lung and how?
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Do not want to put blood into the lungs (uninflated) and so the Ductus Arteriosus shunts blood from pulmonary trunk out of right ventricle into the aorta instead
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What also bypasses the portal (liver) circulation?
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Ductus Venosus
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What is the fossa ovalis called when it is closed?
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Foramen Ovale
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Atrial septation I - where does Septum primum grow and what is the hole formed in it?
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Septum Primum grows from top of heart toward endocardial cushions- hole forms called Ostium Primum
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Atrial septation I - How does the ostium secundum form?
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As ostium primum is obliterated by growth of septum primum, a second ostium secundum forms before closure of ostium primum
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Atrial septation I - Where does the Septum secundum grow and fuse with, what is the name of the resulting hole formed?
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Septum Secundum grows down over ostium secundum and fuses with endocardial cushions, leaving a hole called Foramen Ovale
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Atrial septation I - What type of valve is formed from all of this? Blood returns to what part of heart and then goes where?
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This creates a One-Way Valve allowing blood flow from high pressure right atrium to low pressure left atrium.
Blood returns to right atrium, passes through foramen ovale, between septum primum and secundum, and enters the left atrium through the ostium secundum |
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Atrial septation II - one-way valve allows passage of blood until when
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-One way valve allows passage of blood from RA to LA up to birth
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Atrial septation II - what happens at birth due to clamping of umbilical cord?
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-At birth, with clamping umbilical cord, pressure in RA decreases and pressure in LA increases, because of sudden pulmonary perfusion. This pressure differential closes atrial septum
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Atrial septation II - what happens after birth with septum primum and secundum?
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-After birth, septum primum and septum secundum fuse, obliterating foramen ovale and ostium secundum, so that RA and LA are separated
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Septatation of Ventricles - Most of Interventricular Septum (IVS) forms from Growth of and fusion of...
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Most of Interventricular Septum (IVS) forms from Growth of Ventricular Walls and secondary fusion of walls to form the Muscular Portion of the IVS
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Top part of IVS forms from..., which forms what as a whole
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Top part of IVS forms from inferior endocardial cushion. This forms membranous portion of IVS
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What types of circulation are the left and right ventricle involved in (1 each)
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Left ventricle: systemic circulation
Right ventricle: pulmonary circulation |
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Growth of septa in ventricles - what happens to the tissues surrounding atrioventricular canal? How does the ventricular outflow tract grow? Significance of these growths
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-Tissues surrounding atrioventricular canal grow together and fuse, to separate one common orifice into left and right atrioventricular canals.
-Ventricular outflow tract separated by similar growth of tissues into systemic and pulmonary outflow tracts. -Heart development is now essentially complete |
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DiGeorge syndrome - abnormalities found, results from?
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Craniofacial, thymic, parathyroid, cardiovascular, immune system abnormalities
Results from abnormal neural crest cell migration |
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Cardiac Defects - why are many defects possible, 8% of the defects are b/c of what, 2% b/c of what, remaining 90% b/c of what
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-Because of complexity of cardiogenesis, many defects possible
-About 8% Genetic (Down Syndrome) and 2% Environmental (Alcoholism) -Remaining 90% of defects are multifactorial-both genetic and environmental |
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Cardiovascular defects MOST COMMON category of what
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Cardiovascular defects MOST COMMON category of congenital birth defects, accounting for about 1% of all malformations in live-born children
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Agents causing cardiovascular defects (4)
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1) RUBELLA VIRUS (German measles)
2) thalidomide 3) Isoretinoin (in some OTC acne meds) 4) ALCOHOL |
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Maternal conditions associated with CV defects (2)
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1)Insulin-dependent diabetes mellitus
2)hypertension |
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Chromosomal Anomalies and Heart Defects - What percentage of children with chromosomal anomalies, Edwards syndrome, and Down syndrome+DiGeorge syndrome+Goldenhar syndrome have heart defects?
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-33% of children with chromosomal anomalies have heart defects
-100% of children with Edwards syndrome (trisomy 18) have heart defects -Down syndrome (trisomy 21), DiGeorge syndrome, Goldenhar syndrome all associated with heart defects |
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Ventricular Septal Defects (VSD)- most common..., in how many births, what happens to blood volume in pulmonary aorta, most commonly involves what
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-MOST COMMON congenital cardiac defect
-12/10,000 births -Blood volume in pulmonary artery 1.2-1.7 times more abundant than in aorta *Most commonly involves Membranous Portion of IVS, but can also involve membranous and muscular portion of IVS |
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Tetralogy of Fallot - caused by what, fatal?, correctable? symptoms in children
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-Caused by abnormal partitioning of truncus arteriosus and conus cordis (ventricular outflow tract)
-Not fatal, 9.6/10,000 births, surgically correctable- blue baby operation -Children have inadequate pulmonary blood flow, thus are cyanotic, easily fatigued, listless, have digital clubbing (poor peripheral perfusion) |
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Four Features of Tetralogy of Fallot
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Four features:
1) Pulmonary (artery) stenosis (narrowing) 2) VSD (Ventricular Septal Defects) 3) Overriding (misplaced-over VSD) aorta 4) Right ventricular hypertrophy |
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Fetal Circulation
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-Oxygenation of fetal blood occurs in PLACENTA not lungs
-Deoxygenated blood arrives at placenta from UMBILICAL ARTERIES, branches of descending aorta -Blood is oxygenated and returns from placenta via UMBILICAL VEIN -Oxygenated fetal blood bypasses liver via DUCTUS VENOSUS and enters IVC -Returns to RA, some passes through FORAMEN OVALE to LA, then LV, then aorta -Rest of blood leaves RA, enters RV, exits pulmonary artery but bypasses lungs through DUCTUS ARTERIOSUS to aorta |
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Changes in Hemodynamics at Birth - 2 Big Changes
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1) Placental perfusion ceases abruptly
2) Pulmonary perfusion begins suddenly |
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Changes in Hemodynamics at Birth - What happens to the pressure in the RA and LA and why? What does this pressure differential lead to?
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-Pressure DECREASES IN RIGHT ATRIUM because of sudden decrease in blood volume draining from placenta
-Pressure in LEFT ATRIUM INCREASES because of sudden inflation and perfusion of lungs *Pressure differential closes septum primum over foramen ovale - atrial septum completed |
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Changes in Hemodynamics at Birth - What happens to the Ductus Venosus and Ductus Arteriosus?
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-Ductus venosus degenerates and ligamentum teres hepatis forms instead
-Ductus arteriosus is shut off and normally becomes ligamentum arteriosum |
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Establishment of Adult Circulation
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-Now, right ventricle contracts, sending blood to lungs via pulmonary arteries.
-Blood oxygenated in lungs, returns to left atrium via pulmonary veins -Oxygenated blood enters left ventricle, pumped out into aorta. -After circulation through body, deoxygenated blood enters superior and inferior vena cava, return to right atrium, enters right ventricle, and passes again to pulmonary arteries |
