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169 Cards in this Set
- Front
- Back
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What are the stages in formation of the fetal heart?
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primative tube, bulbous cordis/ ventricles/ atria/ sinus venosus, cardiac looping, differentiation and septation
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What is the septum transversum?
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it separates the heart from the peritoneal space
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What is a peritoneopericardial diaphragmatic hernia?
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it is a malformation of the septum transversum which is a rent in the diaphragm so abdominal contents are in the pericardial space ( liver, fat, intestines)- incidental finding in cats
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What is the flow of blood through the cardiac tube?
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umbilical veins to the cardinal veins to the sinus venosus to the primitive atrium to the bulbus cordis to the truncus arteriosus and out the aortic sac
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What occurs during cardiac looping?
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it is when the atria migrate dorsally and the ventrical migrates ventrally to position the atria dorsal to the ventricles
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What is the sinus venosus?
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it is the site of drainage of embryonic venous return- the cardinal veins (fetus) and the umbilical veins (high oxygen)
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What is the common atrioventricular canal?
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it is a congenital defect where the ventrical does not divide/ separate
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What is the fetal origin of the aorta and pulmonary artery?
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the truncus arteriousus
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What is the atrioventricular canal?
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it is the connection between the atrium and ventricle
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What are conotruncal ridges/ cushions?
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they separate the truncus arteriosus into the aorta and pulmonary artery
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What are endocardial cushions?
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they separate the atria and ventricles and help form the A-V valves
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What is the difference between the septum primum and the septum secundum?
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the septum primum separates the atria into two chambers, the septum secundum is the dorsal septum between the atria
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What occurs during atrial septation?
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the septum primum grows and its dorsal part disappears, the septum secundum does not grow all the way down to connect with the septum primum so it creates a flap over the foramen ovale as blood moves from the right atrium to the left atrium because it is already oxygenated by the placenta and does not need to go through the lungs
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How does the placenta replace the lungs in the primitive heart?
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without pulmonary resistance (caused by functioning lungs) the blood flows from the right to left atrium, down the descending aorta to the umbilical artery to the placenta then back up and around again
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What is a portosystemic shunt?
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when the blood from the umbilical vein continues to flow through the ductus venosus into the caudal vena cava functionally avoiding the liver which leads to hepatic encephalopathy
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What are the key changes to the heart at birth?
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the ductus venosus closes, the foramen ovale closes (due to pressure), the ductus arteriosus closes (due to vascular smooth muscle constriction, pulmonary vascular resistance changes and decreases the resistance in arteries to allow flow
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During the formation of the aorta and pulmonary arteries, how many arches are part of the dorsal aorta?
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six pairs
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Aortic arch of the fetus becomes the definitive aortic arch?
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the left 4th
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Which fetal aortic arch becomes the ductus arteriosus and the pulmonary artery?
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the left 6th arch
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What is the resulting defect if the right 4th fetal aortic arch persists?
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vascular ring anomaly where the arch runs right to left and traps the esophagus. causes regurgitation of solid food
important in puppies that regurgitate at weaning |
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How do you treat a vascular ring anomaly?
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cut the ligamentum arteriosus on the left side and twist the esophagus out of the ring
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Why doesn't the foramen ovale fuse during development?
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the pressure in the right atrium is higher than that in the left in the fetus, when the animal is born, pulmonary flow increases the pressure on the left side and functionally closes the flap until it seals shut
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What forms the two cardiac tubes that will become the cardiac tube?
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cells from the mesenchyme
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What are the four major regions of the cardiac tube?
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the sinus venosus, primitive atria, primitive ventricle and bulbus cordis
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What is the source of the aortic arches?
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the truncus arteriosus that extends from the bulbus cordis to form the aortic sac
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Where is the primitive heart situated?
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near the foregut and dorsal to the septum transversum
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What structure helps separate the pericardial and the peritoneal spaces?
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the septum transversum
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What is the direction of blood flow in the primitive heart?
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from the sinus venosus (bottom) to the aortic sac (top)
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What is the movement of the sections of the primitive heart during cardiac looping?
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the bulbous cordis folds and bends to the right, caudally and ventrally; the primitive ventricle moves to the left, the sinus venosus and primitive atrium migrates cranially and dorsally
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What three sites does the sinus venosus collect blood from?
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the vitelline veins of the yolk sac, the umbilical venous drainage and the cardinal venous drainage
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Where do the cardinal and umbilical veins collect blood from?
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the cardinal collect blood from the fetus, the umbilical veins collect blood from the placenta
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Where does the sinus venosus drain?
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into the developing common atrium
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What part of the primitive heart becomes the coronary sinus, cranial vena cava, smooth part of the right atrium and the sinoatrial node?
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parts of the sinous venosus
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the caudal vena cava is derived from what primitive heart component?
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the vitelline veins
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the bulbus cordis contributes substatnially to which ventricle?
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the right ventricle
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What is the fetal origin of the aortic arch system and pulmonary artery?
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the truncus arteriosus and aortic sac
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what opening connects the primitive atrium and ventricle?
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the atrioventricular canal
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How are the AV canals created?
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the endocardial cushions grow into the atrioventricular canal and create separate right and left ventricular inlets
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Following looping and migration, what connects the two ventricles?
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the interventricular foramen
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What is the function of the endocardial cushions?
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they separate the common AV canal, close a large part of the dorsal ventricular septum and contribute to the formation of the septal leaflets of the atrioventricular valves
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What are the conotruncal cushions and what is their function?
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they are ridges that fuse together to separate the aorta and PA
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What is the spiral septum?
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it is the distal truncal septum that spirals to allow the aorta nad PA to twist around each other
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What is the source of the paired aortic arches?
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the aortic sac
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What is the path of the aortic arches?
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they extend from the sac ventrally and arch dorsally to connect to the paired dorsal aorta
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Which aortic arch becomes the final aortic arch?
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the left fourth arch
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How does fetal blood bypass the liver?
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via the ductus venosus
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What is the path of oxygenated blood within the fetus?
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the oxygenated blood from the placenta returns from the umbilical vein and mixes with fetal blood int eh caudal vena cava and is then preferentially directed across the foramen ovale into the left atrium, then it follows the usual path across the left heart
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What is the path of deoxygenated blood in the fetus?
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it returns from the cranial vena cava and enters the right atrium and is preferentially streamed into the right ventricle following into the pulmonary artery. it is then shunted away from the lungs and into the ductus arteriosus and enters the descending aorta to the umbilical arteries to be re-oxygenated in the placenta
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What changes occur in the circulatory system at birth?
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the lungs are oxygenated, pulmonary vascular resistance falls dramatically and blood flows across the lung, the left atrial filling and pressure increases, the flap of the foramen ovale is pushed closed which closes the atrial septum, at the same time incresed oxygen tension inhibits prostaglandins in the ductus arteriosus leading to contraction of ductal smooth muscle and functional closure of the ductus. With disruption of the placenta, the ductus venosus closes
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At what points in the fetus is blood of different oxygen content mixed?
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the caudal vena cava; right atrium; descending aorta
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At birth, how are the oxygenated and deoxygenated blood circulation systems separated?
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by the separation of the placenta and closure of the ductus venosus; bu functional closure of the foramen ovale; and by constriction and anatomic closure of the ductus arteriosus
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What is PDA and when does it occur?
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Patent Ductus Arteriosus occurs when the the developing ductus arteriosus doesn't have enough smooth muscle to constrict when the prostaglandins are inhibited. this allows blood to shunt left-to-right (opposite of fetal circulation) can lead to left-sided heart failure
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What is a ventricular septal defect?
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it is when the connective tissue components of the ventricular septum do not develop properly
common in large animals and cats |
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What are the functions of the cardiovascular system?
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deliver oxygen, nutrient substrates and water to the living tissues
carry hormones and regulatory chemicals while removing carbon dioxide and metabolic wastes thermoregulation support blood-flow dependent functions |
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What are the "blood flow dependent" functions of the body?
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urine formation in kidneys, gas exchange in the lungs, metabolism in working skeletal muscle (fatigue as a sign of heart failure), digestive processes and absorption, and reproductive system functions
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What is the predominant cell type in the heart?
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Myocardium
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Which heart cells are capable of current conduction without nerves?
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Myocardial cells
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What are the major divisions of the heart?
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Two atria, two ventricles and two great vessels that twist around each other cranial and caudally
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How many cardiac valves are there (one-way valves)?
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Four- all are left of the midline except the tricuspid valve
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Where in the heart will you find low oxygen levels?
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Right atrium, right ventricle, and pulmonary artery
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Which parts of the heart have high oxygen levels?
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left atrium, left ventricle, and aorta
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What vessels supply the myocardium?
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the coronary vessels- the cause for heart disease in humans in developed countries
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What is the importance of the connective tissue skeleton of the heart?
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it anchors the valves and insulates the current
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What are the proper names for the pumping and filling of the heart?
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systole- contracts
diastole- ventricles fill |
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What is the flow of blood through the body?
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Vena cava
Right atrium tricuspid valve right ventricle pulmonic valve pulmonary trunk left atrium mitral valve left ventricle aortic valve aorta |
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What do fluid dynamics in microcirculation depend on?
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capillary hydrostatic pressure (forces out of vessel)
capillary oncotic (protein) pressure (forces into vessel) lymph in th einterstitium lymphatics that move the extra fluid through the system |
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What is edema?
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extra fluid that was forced out of the capillaries and is not resorbed
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What is the route of blood in systemic circulation?
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pulmonary venous blood enters the left atrium- left ventricle- aorta then to distributing arteries to regional circulations-arterioles-capillaries-systemic veins- right heart- lungs
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How does the oxygen content differ in pulmonary circulation from
systemic circulation? |
pulmonary circulation has low oxygen in the arteries and high oxygen in the veins
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what is the path of pulmonary circulation?
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right atrium, right ventricle, pulmonary arteries, lobar branches to lungs, arterioles, capillaries, gas exchange in alveoli, pulmonary veins, left heart
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Why is the heart considered four dimensional?
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because it moves over time
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What part of the body contains the most blood at any given time?
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systemic veins
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Where is the heart located?
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between the 2/3rd and 6th ribs
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How does the position of the heart differ in sheep?
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the apex is to the right of the midline (it is to the left in other species)
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Which part of the heart beat can you palpate in the cardiac notch?
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the left apex beat
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Which part of the pericardium is considered the "true" pericardium
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the parietal pericardium that is a reflection of the epicardium
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Where does fluid collect around the heart (normally and pathologically)?
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in the pericardial space
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What are the grooves on the surface of the heart?
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coronary
paraconal (cranial interventricular) subsinuosal (caudal interventricular) |
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Which vessels enter the right atrium?
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the cranial and caudal vena cava, the right and left azygous vein, and the coronary sinus where the coronary veins drain
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What are the parts included in the right atrium/ right ventricle inlet?
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the right atrial cavity: right auricle and atrial septum
the intravenous tubercle which is cranial to the foramen ovale the right AV valve (tricuspid valve) ventricular septum- trabecula septomarginalis (carries signal from muscle to muscle) |
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What are the components of the right atrioventricular apparatus?
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the tricuspid valve
species differences in the number of leaflets the valve annulus (cartilage ring that anchors valve) valve leaflets and cusps (thick parts at the edge) chordae tendinae papillary muscles (2-3 on the right side) |
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What is the supraventricular crest and what is its function?
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it separates the inlet and outlet of the right ventricle
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How does the right ventricle differ grossly from the left ventricle?
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the right ventricular myocardium has ridges called trabeculae carnae and the left side is smooth
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Where is the main pulmonary artery located?
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on the left, cranial, dorsal cardiac border
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Where is the left atrium located relative to other structures?
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midline, dorsal to the left ventrical and caudal to the right auricle, below the tracheal bifurcation
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Why is coughing a sign of left atrial enlargment?
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when it enlarges it can compress the left bronchus
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Where is the inlet of the left ventricle?
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it is between the mitral valve leaflets
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Where is the outlet of the left ventricle?
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between the septal leaflet and the ventricular septum
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What is unique about the myocardium of the left ventricle?
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it is arranged in layers that allow it to shorten in three planes and twist during systole (contracts like a boa constrictor)
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What is the most common cardiac disease in dogs and cats?
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cardiomyopathy- a valve is leaky because the papillary muscles aren't working and the annulus is dilated due to dilation of the ventricle
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What are the components of the left atrioventricular valve apparatus (mitral valve)?
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valve annulus
valve leaflets and cusps chordae teindinae papillary muscles atrial wall |
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What are the three leaflets of the aortic valve?
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the right coronary, left coronary, and noncoronary leaflets
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What are the sinuses of valsalva?
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there are 2 and they are openings to the coronary arteries from the aorta
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Why does the aortic valve diastole?
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to prevent backflow of blood
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What are the coronary ostia?
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they are the openings of the two coronary arteries
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Where is the noncoronary cusp of the aortic valve located?
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adjacent to the atrial septum- useful in echo imaging
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Which coronary artery is usually the largest?
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the left
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Where is the circumflex branch of the coronary artery?
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it is off the left coronary artery and follows along the coronary groove
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What are the other names for the paraconal branch?
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cranial interventricular
left anterior descending (issues in humans) |
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What is the major coronary supply to the caudal border of the heart?
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it can be right coronary artery dominant (cats, horses, people) or left coronary artery dominant (dogs) so either can supply the caudal border of the heart
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How many aortic branch vessels do large animals usually have?
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one- a common brachiocephalic trunk
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How many aortic branch vessels do small animals have?
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two- a brachiocephalic artery and the left subclavian artery
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What is the function of the fibrous cartilage skeleton?
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it provides an anchor for cardiac valves
prevents the current flow between atria and ventricles closes a portion of the embryonic ventricular septum |
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Which valves have the best developed fibrous rings?
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the aortic valve and mitral valve
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What are the parts of the impulse-forming and conduction system?
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the sinoatrial node, the atrioventricular node and the bundle of his
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Which portion of the conduction system is resistant to increased serum potassium levels?
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the sinoatrial node
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What is the path of impulse and conduction within the heart?
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the sa node initiates in the right atrium- current spreads across teh atria and internodal pathways to the AV node- AV slows the spread of the current to the bundle of His- moves more rapidly across the His-Purkinje system- Purkinje cells carry it to myocytes- cell to cell propagation occurs
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How does the pattern of purkinje cell distribution differ among species and what affect does this have?
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in large animals the purkinje system penetrates deeper into the heart than in small animals (horses are in between)- likely because of the size of the heart/ distance the impulse needs to travel. This will also affect the appearance of the QRS complex in the ECG
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Where do the cardiac nerves enter the heart and which nerves are they?
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enter at the cardiac base
cervical/first thoracic ganglia/ ansa subclavia vagus nerve/ recurrent laryngeal nerve |
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What affect do the sympathetic nervous system and parasympathetic nervous system have on the heart?
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sympathetic stimulates heart rate, contractility, conduction of current
parasympathetic depresses the heart rate, contractility, conduction |
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What is the significance of the proximity of the phrenic nerve to the heart?
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phrenic nerve runs over the heart and can be stimulated to be more excitable in metabolic conditions ( like a horse that just ran a race) so when the heart thumps it will cause "synchronous diaphragmatic flutter"
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What are the types of arteries?
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elastic arteries, muscular arteries, arterioles and metarterioles
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What are the layers of the arteries?
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intima, media, adventitia +/- internal elastic lamina
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What is the vasa vasorum?
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it is the vascular supply to a larger artery or vein and is located within the adventitia
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What is the function of the muscular layers in arteries?
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they are located in the media and provide tone and facilitate vasoconstruction and vasodilation
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How do veins differ from arteries?
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They have a larger lumen when compared to arteries, low pressure system, thinner-walled since they are designed to carry and store a larger volume of blood
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What is the histologic organization of veins?
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three layers but with a thinner media
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How does constriction of a vessel change blood flow?
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it increases vascular resistance behind and decreases blood flow in front
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What types of tissue make up the epicardium?
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it is the mesothelial layer, subepicardial fat, extramural coronary arteries and veins
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Where are the purkinje fibers located within the layers of the heart wall?
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in the endocardium along with endothelial cells, subendocardial connective tissue
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What type of tissue is found in the myocardium?
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multiple layers of striated muscle to create a "wringing" contraction
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What are cardiomyocytes?
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striated muscle with branching cytoplasm and a large central nucleus
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What are the anchors for cardiomyocytes?
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intercalated discs
gap junctions- allow low resistance passage of current adherent junctions- anchor myofilaments desmosomes- anchors |
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What is located within the interccellular spaces of cardiac tissue?
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capillaries, fibroblasts, supporting collagen, adherent molecules
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What defines arterioles?
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minimal elastic tissue, thick media/ muscle layer
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What is the function of arterioles?
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they control vascular resistance and control perfusion to regional circulations
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What type of fibers are found in the I band of the cardiomyocyte?
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actin myofilaments
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What type of fibers are found in the A band of the cardiomyocyte?
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myosin and overlapping actin myofilaments
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What are cardiac valves composed of histologically?
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endocardium over thick central fibrous tissue- connective tissue is contiguous with the fibrous skeleton of the heart and the chordae tendinae
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What are the specialized cells within the heart?
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purkinje cells, SA node, AV node, aortic/carotid bodies
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What is the difference between the high and low frequency echocardiography?
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high frequency: high resolution, low penetration
low frequency: lower resolution, higher penetration |
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What is the process of electroimpulses in echocardiography?
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electrical energy- mechanical (vibration)- emission (1540 m/s through tissue)- reflection at cells/ tissue surfaces- reception (probe)- generation of image
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What level of frame rate do you need for a smooth image on electrocardiography?
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>60 frames per second
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What is the frequency range of echocardiography equipment?
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2-16 MHz`
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What are the main modes of echocardiography?
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two dimensional
three dimensional Mmode Doppler echocardiography |
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What is the main benefit of 2D echocardiography?
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it allows the two-dimensional assessment of single parts of the heart in their anatomically correct position during multiple cardiac cycles
Real-time |
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What are the parts of the general subjective assessment in 2D echocardiography?
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size, shape, motion, contents ("smoke"), echogenicity, thickness, abnormal anatomy
Chambers Septa Endocardium Valves Myocardium Pericardium Great Vessels Extracardiac |
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What are the standard image planes of 2D echocardiography?
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right parasternal long axis view
right parasternal short axis view right parasternal subcostal view left parasternal apical view |
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What view would you use to detect aortic stenosis on ECG?
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right parasternal long axis (5-chamber) view which shows the right ventricle, the left ventricle, right atrium, left auricle and aorta
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What does smoke in the cat heart signify?
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thromboembolic disease
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Which echocardiographic view is the "fish mouth" view?
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the right parasternal short axis view at the mitral valve level (mitral valve is the fish mouth)
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Which chambers are visible on the left parasternal apical 5-chamber view?
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the left ventrical, left atrium, right ventricle, right atrium, and aorta
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What is the best way to position a right parasternal subcostal ECG view?
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it is important to make sure that the aorta goes down in a straight line
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What is the benefit of M-mode echocardiography?
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it allows the one-dimensional assessment of the motion of certain parts of the heart recorded along a single ultrasound line during multiple cardiac cycles with high temporal resolution
Time-motion graph several thousand fps temporal resolution |
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What type of ECG is best for assessing left ventricular systolic function?
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M-mode echocardiography to measure the LV shortening fraction
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Who discovered the doppler effect?
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Christian Andreas Doppler in 1842
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How does flow toward and flow away effect the doppler principle?
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flow toward is a positive shift (higher pitch)
flow away is a negative shift (lower pitch) |
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What information does doppler ECG give you?
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information on blood flow:
direction velocity quality |
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What are the 3 systems of doppler echocardiography?
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pulsed wave
continuous wave color flow doppler |
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What is the purpose of pulsed wave doppler?
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it measures blood flow at an exact location distant to the transducer
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What is the purpose of continous wave doppler?
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it measures the blood flow along one ultrasound line
can tell velocities but gives range ambiguity |
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What are the two flow qualities and which is normal?
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laminar- normal
turbulent- abnormal: valve stenosis valve insufficiency shunt flow |
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What do the colors on color flow doppler mean?
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red is toward the transducer; blue is away; turbulent flow is red and blue mixed with green
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Where is mild flow turbulence normal in the heart?
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in the left and right ventricular outflow tract
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What does flow turbulence on ECG indicate?
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obstruction, insufficiency, or shunt
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How can you calculate peak pressure gradients from ECG?
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peak flow velocities difference between the expelling and receiving chambers using the modified Bernoulli equation
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Which ventricular flow is monophasic and which is biphasic?
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monophasic- ventricular outflow
biphasic- ventricular inflow |
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What is the modified bernoulli equation and what is its use?
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pressure gradient (mm Hg)= 4 x Velocity (m/s) max ^2
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In systole, what is the difference in pressure between the RV and PA?
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~4mmHg
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What is normal flow between the left and right ventricular inflow tract?
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peak velocities less than 1.2m/s
E>A E:A 1.0 to 2.0 no mitral regurg trace tricuspid regurgitation |
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What is the normal heart: body weight ratio?
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about 0.75 to 1.25
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What is the general wall thicknesses of the LV: RV walls?
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about 3.1
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What does euthanasia by cardiac puncture cause that could be misinterpreted?
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it causes blood and crystals within the pericardial space
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What changes does rigor mortis cause on the heart post-mortem?
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LV will be more contracted than RV
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How do you distinguish post-mortem clots from an antemortem thrombus?
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a thrombus would be attached to the cardiac wall, while a post-mortem clot is not attached
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Epicardial lymphatics (white streaks) are common post-mortem findings in what species?
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cows
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In a neonate 1-3 days old , why could there be probe patency of PFO and ductus arteriosus?
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the ductus does not fibrose until more than 3 weeks of age, so it may be functionally sealed, but not completely
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What is the normal relationship between the septum and left ventricular free wall?
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they are usually the same size
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How do post-mortem clots appear different than pre-mortem?
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they are typically dark red, appear fatty-yellow if RBCs sediment after death leaving plasma elements
also not firmly attached to the intimal wall |
