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321 Cards in this Set
- Front
- Back
What is atherosclerosis?
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It is the accumulation of fat and other materials along the lumen of blood vessels
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What can atherosclerosis lead to?
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Myocardial infarct, stroke, aneurysm, and peripheral cardiac disease
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What can atherosclerosis be manifested in?
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Dysfunction related to the heart and/or brain
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What type of progression does atherosclerosis have?
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Slow and predictable
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What is the lumen of a typical blood vessel lined by?
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A single layer of endothelial cellls resting on a basement membrane
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What lies underneath the basement membrane of the blood vessel?
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The lamina propria
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What is the lamina propria made of?
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Collagen and elastic fibers and smooth muscle cells
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What do the endothelial cells, basement membrane and lamina propria form?
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The intima
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What is found after the intima?
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The media
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What is the media composed of?
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Internal and external elastic membranes separated by a thick layer of smooth muscle and reticular fibers
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What is the outermost layer of the blood vessel?
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Adventitia
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What is the vasa vasorum?
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The blood supply of the adventitia and media
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What is the difference with how the intima and adventitia and media receive oxygen and nutrients?
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The adventitia and media receive these from the blood supply the vasa vasorum, while the intima receives it from the lumen of the blood vessel
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What are fatty streaks?
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The accumulation of lipid in and out of the surface of the intima
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Are fatty streaks indicative of any pathology?
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No. They are common and harmless
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Where do fatty streaks predominantly occur?
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In the aorta and coronary arteries
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What is the stage after formation of fatty streaks in the development of atherosclerosis?
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The formation of a fibrous plaque after formation of foam cells
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What does a fibrous plaque do?
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Changes the morphology of the normal vessel
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What can a fibrous plaque lead to?
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An advanced lesion
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What occurs in this advanced lesion during atherosclerosis?
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Calcification, hemorrhage, ulceration or thrombosis
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What does an even more advanced lesion lead to?
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Decreased blood flow to the periphery
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What can this decreased blood flow to the periphery due to the advanced lesion in atherosclerosis lead to?
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Stroke, myocardial infarct, transient ischemic attacks, angina (ischemia of the heart muscle), peripheral arterial disease, gangrene and necrosis
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What is peripheral arterial disease characterized by?
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Claudication (limping) - pain upon exercise and even during rest
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What are the two main components of the pathogenesis of atherosclerosis?
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Endothelial dysfunction and chronic inflammation
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What are the four steps to the mechanism of atherosclerosis and vessel plaque formation?
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-Damage to endothelia
-Platelet aggregation and release of inflammatory mediators -Migration and proliferation of medial smooth muscle cells from the media into the intima -Sythesis of connective tissue and deposition of lipids and calcification |
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What dose the initial damage to the endothelium depend on?
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THe hemodynamics and lipid content of the blood
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What are some components of connective tissue that are synthesized after the migration of smooth muscle cells?
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Collagen and other consituents of the ECM
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What can the formation of a plaque after (synthesis of connective tissue, deposition of lipids and calcification) lead to?
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Thrombosis (if fibrous plaque is damaged)
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How can hemodynamic stress lead to endothelium damage and thus atherosclerosis?
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The flow of blood against the endothelium can lead to endothelium damage and release of inflammatory mediators
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What does the release of mediators after damage to the endothelium result in?
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Further damage due to the recruitment of leukocytes, etc as well as the differentiation and migration of smooth muscle cells from the media to the intima
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How are "foam cells" formed?
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-Monocytes infiltrate the intima and activated macrophages start to take up lipids and get bigger and turn into foam cells. Smooth muscle cells can also become foam cells
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What does the formation of foam cells lead to?
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Narrowing of the lumen of the vessel
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What is the damage during atherosclerosis intensified by?
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Smooth muscle cell proliferation
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Which cells release factors that stimulate smooth muscle cell proliferation?
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Platelets, Leukocytes, Endothelial cells, monocytes/macrophages and fibroblasts
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What are some examples of mediators that stimulate smooth muscle cell proliferation?
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-Macrophage derived growth factor
-Platelet derived growth factor -Fibroblast growth factor -Interleukins -Interferons |
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How does cholesterol affect the development of atherosclerosis?
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-LDLs present at site of inflammation are oxidized and taken up by macrophages. HDL doesnt remove all the cholesterol and you get the accumulation of lipids in the cytoplasm and thus the formation of lipid globules resulting in a foamy appearance-> "foam cells"
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What does macrophage interaction with T cell lead to?
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Their communication signals smooth muscle cells for proliferation
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What is a lipoprotein?
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Lipid filled particles that mediate their transport in the blood
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What are lipoprotein particles made of?
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A single layer phospholipid that has some free cholesterol and apoproteins. In the core, has triglycerides and cholesterol esters
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What are apoproteins?
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Receptors mediation the internalization of the particle into cells
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What are the four types of lipoproteins?
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-Chylomicron
-Very Low Density Lipoprotein (VLDL) -Low Density Lipoprotein (LDL) -High Density Lipoprotein (HDL) |
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What is a chylomicron?
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Particle in which lipids are transiently stored after their absorption in the small intestine
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What is a chylomicron characterized by?
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High triglyceride content
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What are some differences between LDLs and HDLs?
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LDLs are rich in cholesterol and HDLs have lower cholesterol and higher protein content
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Why is HDL known as the good lipoprotein?
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Its role is to take the lipids from the tissues and deliver it to the liver where the synthesis and assembly of different lipoproteins takes place
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What is the role of livers in lipoproteins?
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Livers produce the lipoproteins and as an output, produce VLDLS or LDLs
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How are lipoprotein contents released into the periphery?
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They are acted on by lipoprotein lipases
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How do lipoproteins increase the risk for atherosclerosis?
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They can be taken up by the vessel walls and accelerate the process of plaque formation
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How do tissue cells take up the lipoprotein particles?
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The LDL has an APO-B protein that binds to the LDLR on the surface of the cell and mediates phagocytosis
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How do HDLs act?
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They bind to cells with an HDLR via APO-A and are internalized. They take up the cells excess lipids and return to the liver. This decreases the fat content of the blood vessel wall and thus act in as a defense against atherosclerosis
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What is the physiological role of LDLs?
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Provide muscle cells and fat cells with lipids for energy
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What does the formation of foam cells within the vessel lead to?
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More monocytes enter the vessel's wall
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What occurs after the development of foam cells?
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Fibrosis
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How does fibrosis result?
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Smooth muscle cells synthesize and deposite collagen, elastin, and glycoproteins in the wall of the vessel
-Some smooth muscle cells also become foam cells |
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What happens to the smooth muscle cells synthesizing this fibrous tissue?
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They lose their ability to contract and become synthetic cells
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What does the recruitment of platelets to this site cause?
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Platelet aggregation
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What is the rational that obesity can lead to atherosclerosis as a complication?
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Intraabdominal obesity is characterized by high triglycerides and thus high LDL and low HDL. This leads to increased foam cell formation and thus inflammation leading to the development of atherosclerosis
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How can the thickness and stability of the fibrous "cap" play into the complications of atherosclerosis?
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If the cap is thin and unstable it can rupture-> leading to the formation of a thrombus (blood clot) which could block the artery.
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What is an aneurysm?
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The atherosclerosis changes the elastic properties of the vessel wall, leading to its weakening. THe vessel cannot withstand the pressure at the atherosclerotic site, it will inflate like a balloon = aneurysm
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What are the risk factors for atherosclerosis?
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-Smoking
-High LDL -Low HDL -Hypertension -Diabetes mellitus -Lack of exercise |
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How does smoking put someone more at risk for atherosclerosis?
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-There is decreased oxygen supply to the endothelium due to the increased carboxy-Hb
-Promotes platelet aggregation -Decreases HDL -Increases BP -CO concentration increases -Increase in oxygen free radicals -Vasoconstriction triggered by nicotine on the ANS |
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What does the presence of CO in the body cause?
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Blocks ATP production
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Which types of fatty acids are protective against atherosclerosis?
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Unsaturated fatty acids
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What are five functions of endothelial cells?
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1-Permeability barrier
2-Non-thrombogenic properties 3-Metabolism of vasoactive substances 4-Production of growth factors 5-Connective tissue formation |
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How are endothelial cells non-thrombogenic?
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Their surfaces are non-thrombogenic and they secrete anti thrombogenic agents such as PGI2
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What does damage of endothelial cells lead to?
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-Activation of platelets by exposure to collagen (like in the lamina propria) and thrombus formation, triggering inflammation and plaque formation.
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What are three ways that atherosclerosis promotes thrombosis?
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Alterations in blood flow
Damage to endothelium Changes in blood composition |
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Why do changes in blood flow lead to development of thrombosis?
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-Slowing of blood concentrates platelets
-Turbulence causes damage (resulting in more exposure of collagen) |
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Wha are some changes in the composition of blood that lead to the development of thrombosis?
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Increased platelets, fibrinogen and prothrombin and increased platelet adhesiveness and reactivity
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What is deep vein thrombosis?
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Occurs in the deep vein of the legs - there is a low flow of blood when the legs arent move contributing to the formation of a thrombus
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What is an embolus?
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A portion of the thrombus that breaks off into the circulation
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What is the difference between a mural and occlusive thrombus?
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A mural thrombus does not completely cut of blood flow while an occlusive thrombus does
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Where do red thrombi tend to form?
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In veins around the valves
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What are some sequels of thrombus formation?
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-The thrombus can be lysed- allowing the blood vessel to be opened up
-The process of recanalization can occur -Thrombus can calcify -The thrombus can be incorporated into the blood vessel wall-> opening up the vessel -It can form an embolus |
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Besides a piece of thrombus, what are some other ways an embolus can form?
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-Fat embolus from the fracture of a bone
-Tumor embolus -Foreign material -Air bubbles |
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What are some causes of embolism?
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Venous injury
Poor blood circulation Increased blood clotting |
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How can venous injury result?
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From surgery or trauma
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How can poor blood circulation result?
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Heart failure
Increased blood viscosity Small blood clots Prolonged immobilization |
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How can increased blood clotting occur?
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Anti-clotting factors deficiencies, autoimmune disorders, certain types of cancer, platelet disorders
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What is a pulmonary embolus?
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When the embolus follows the circulation to the heart, it can then lodge itself into the lungs
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What happens if the pulmonary embolus is large?
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This will restrict a large portion of the tissue and the person will have a pulmonary infarct
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Why is multiple small emboli not life threatening?
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-The contribution of the collateral vasculature (bronchial can anastomose to pulmonary) allows perfusion of the restricted area
-There is some amount of reserve in the pulmonary vasculature |
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How does diameter affect blood flow?
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Flow rate is proportional to the diameter ^4
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Which areas of vessels are prone to plaque formation?
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Branchpoints (ex of aorta, carotids (head + neck), iliac (branchpoints of aorta), femoral (provides thigh)
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What are some ways to correct obstruction of blood flow?
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-Remove plaque and insert a stent (counteracts constriction)
-Replace vessel by a graft -Induce angioplasty (mechanically widening a constricted blood vessel) -Do a bypass |
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What is an alternative method to correct obstructed blood vessels?
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Arterectomy
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What is arterectomy?
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Surgical removal of part of an artery
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How are aneurysms (bulging of blood vessels) not occuring all the time?
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A vessel is subjected to blood presure, but is able to have sufficient elasticity to resist and return to its normal state after being subjected to the pressure of the blood
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What are two cases that an aneurysm can form?
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-BP is too high
-Wall of vessel is weakened |
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How is a fusiform aneurysm caused?
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Damage to whole circumfrence of blood vessel wall elastic properties
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How is a saccular aneurysm caused?
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If the damage is restricted to one segment
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What is the difference between how a fusiform aneurysm and saccular aneurysm appears?
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Fusiform -> like a splindle outpouch
Saccular-> localized bulge |
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What are some complications of an aneurysm?
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The buldge can cause pressure
The buldge can rupture leading to hemorrhage |
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What happens when there is a rupture of an aortic aneurysm?
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Massive retroperitoneal hemorrhage
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What is a Berry aneurysm?
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Brain aneurysm that when ruptures leads to STROKE
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How do thrombuses work with aneurysms?
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Exert a protective effect
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How do thrombi exert a protective effect of aneurysms?
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They can absorb stress- protecting the underlying aneurysm wall
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What is a dissecting aneurysm?
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A portion of the blood literally dissects a portion of vessel wall (the media)
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What happens in a dissecting aneurysm?
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The weakened part of the wall rips, and blood flows under the wall into the media- creating two lumens. The blood then travels in this "false lumen" within the media, which is separated from the true lumen by the "intima"
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How can blood reenter the true lumen from the false lumen?
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The blood will travel causing secondary tears to the intima, which will eventuall rupture allowing blood to reenter the true lumen of the blood vessel
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What is dangerous about the formation of this "false lumen"?
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The pressure can occlude the true lumen and block the vessels. This results in a restriction of blood flow to some of the major organs, which can be very painful
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Where are varicose veins typically seen?
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SUperficial veins
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Why do varicose veins usually develop in superficial veins?
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Superficial veins function to drain into deep veins and varicosities develop as a dysfunction of the valves in these vessels. Blood could go in the opposite direction
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How are the varicose veins distorted?
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The normal one way flow is not competent, and there is a backflow of blood resulting in dilation and distortion of the vein shapes. Some of the veins bulge
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What does walking do to venous pressure?
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It substantially decreases the venous pressure in the lower part of the body (which is a result of gravity)
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What are some risk factors of varicose veins?
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-Hereditary: defective valves
-Lack of muscle tone (cant contract muscle to push blood back up along veins) -Obesity with fat replacing muscle in the legs -Periods of prolonged standing leading to a weakening of the wall |
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Why are the legs the most suspetible to varicose vein development?
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2/3 of blood is in veins, and when standing, gravity increases the pressure of the blood in the veins by bringing in more blood
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What are some complications of varicose veins?
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Ulceration, fibrotic thickening, and pigmentary changes
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Who is more susceptible to premature deaths of cardiovascular disease?
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Premature deaths of cardiovascular disease is more frequent in men than women
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What is hypertension?
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A sustained elevation in resting blood pressure
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How is hypertension defined?
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When systolic pressure is greater than or equal to 140
When diastolic pressure is greater than or equal to 90 |
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What is the optimal blood pressure?
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120/80
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What is a blood pressure between 120/80 and 140/90 considered to be?
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Tolerable: mortality rate does increase however, but not as dramatic as when BP is higher than that defined for hypertension (140/90)
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How does temperature affect blood pressure?
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Blood pressure decreases at higher temperatures due to vasodilation and perspiration
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How does exercise affect blood pressure?
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During exercise, blood pressure increases
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How does the exercise BP compare between a healthy individual and one with hypertension?
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Before exercise, the hypertensive patient has a higher BP but both of their BP's rise to about the same level. After exercise, the healthy person's BP drops to lower than the hypertensive patient
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Should BP increase with age?
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NO!!!!
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What is the most common form of hypertension?
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Essential (idiopathic) hypertension
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What is essential (idiopathic) hypertension?
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No primary diseases are causing the hypertension
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What are some secondary causes to blood pressure?
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Renal malfunction and hormonal imbalance
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What is blood pressure control mediated by?
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ANS
Renin-angiotensin aldosterone system Salt and water intake in diet Structural changes in the blood vessels Hormonal control |
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How does salt intake correlate with BP?
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Individuals that have problems exreting sodium are at risk for hypertension, since there is a linear relationship between salt intake and blood pressure
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How does alcohol correlate with BP?
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Those that consume high levels of alcohol are at risk for hypertension
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How does BMI relate to hypertension?
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Increased BMI increase rates of hypertension
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What are some structural changes of blood vessels associated with increased blood pressure?
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-Structural thickening of the vessel wall
-Increased neural or hormonal activity stimulating vessel constriction |
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How does hypertension lead to atherosclerosis?
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High BP means an increased damage to the endothelial wall of the vessel
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How does atherosclerosis lead to increased blood pressure?
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Atherosclerosis will increase vessel resistance and thus increase the BP
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How does hypertension affect the heart?
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The heart must pump harder against the increased resistance and this results in cardiac hypertrophy and possible dilation of ventricles
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What are some affects of hypertension on arteries?
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-There is hyperplasia of the smooth muscle
-Possible fibrinoid necrosis of the arterial wall |
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What kind of implications do the structural changes of the arteries result in?
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-Possible aneurisms in the brain
-Impairined blood flow in kidney resulting in renal failure -Impaired blood flow to eyes resulting in impaired vision |
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What does atherosclerosis in the coronary arteries lead to?
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Angina or infarct
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What does atherosclerosis in the cerebral arteries lead to?
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An aneurysm that leads to hemorrhage or stroke
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What are the four major diseases associated with hypertension?
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-Coronary heart disease
-Intermittent cluadication -atherothrombotic brain infarction -Congestive failure |
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What is coronary heart disease?
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Failure of coronary circulation to supply adequate circulation to cardiac muscle and surrounding tissue
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What is intermittent claudication?
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Intermittent claudication in and of itself is often a symptom of severe atherosclerotic disease of the peripheral vascular system and leads to arterial insufficiency.
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What is atherothrombotic brain infarction?
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-Atherosclerosis leading to thrombus formation, resulting in death of brain tissue due to lack of blood supply
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What is congestive failrue?
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Low cardiac output
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What are some manifestations of hypertension syndrome?
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Obesity, abnormal lipid and glucose metabolism, ventricular hypertrophy and dysfunction, changes in blood clotting function, renal function
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What is the first line of high BP treatment?
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Change risk factors in life (weight, alchohol intake, sodium intake, physical exercise
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Where do drugs act to target the control mechanisms of BP?
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-Brain central regulators
-Peripheral branches of the nervous system -Arterial smooth muscle -Kidney -Heart, cardial contractility |
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What is ischemic heart disease?
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Another term for coronary heart disease: inadequate blood flow to the cardiac muscles
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Which coronary artery (supplies heart) is the site of most problems?
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The left anterior descending artery
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Where do atherosclerotic plaques in the coronary arteries tend to be deposited?
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In the main/proximal bifurcations and branches
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What is the #1 cause of death in North America?
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Coronary Heart Disease
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What develops to be really severe even BEFORE symptoms of coronary heart disease occur?
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Stenosis
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What is stenosis?
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Decrease in lumen size
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What can angina result from in patients with coronary heart disease?
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Insufficient blood to the cardiac muscles during exercise (lumen near the site of plaque is only large enough to accomodate passage of blood at resting conditions)
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What is angina pectoris characterized?
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Pain in the chest and shoulder and surrounding areas
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What is angina pectoris a result from?
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Imbalance between demand of cardiac muscle and supply of the coronary arteries
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What does the demand of oxygen by the cardiac muscle depend on?
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Myocardial workload
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What is "afterload"?
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Blood pressure - the resistance in the vascular "tree" that the heart has to pump against
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What is "preload"?
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Venous return - the amount of blood coming back the heart that it must pump out again
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What is the rate and force of contraction controlled by?
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The ANS and adrenaline
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What increases with exercise?
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Afterload, preload, and rate and force of contraction
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What are two key characteristics of a cardiac myocyte?
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-It has a high energy requirement but a low energy reserve
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Why does the cardiac myocyte have such a high energy requirement?
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-It has to maintain the membrane potenial and the conduction of signals
-It has to perform mechanical contraction |
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Why does one feel pain in the left shoulder and arm during cardiac pain?
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There is the convergence of the afferent pathways in the spinal cord - cant discriminate between the two
-This convergence can vary between individuals |
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What is "variant angina" characterized by?
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Coronary artery spasms in the smooth muscle of the wall of the arteries may cut off the blood flow through the vessel
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What is nitroglycerine?
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A vasodilator that may be able to restore blood flow that was diminished by coronary artery spasms in variant angina
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How is inadequate blood flow in coronary artery disease detected on an ECG?
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Depressed ST segment
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To treat angina, what must one do?
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Restore adequate flow to the coronary arteries
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How does nitroglycerine decrease the workload of the heart?
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It dilates the veins MORE than the arteries
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How is this decreased workload caused by nitroglycerine manifested?
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-Decreases the resistance in the arterial tree, decreasing afterload
-Decreasing contractility (to increase dilation) and increasing capacitance- leads to decreased preload |
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In what situations is nitroglycerine able to work?
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When there is a fibrolipid plaque collected to one side of the blood vessel
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In what situations is nitroglycerine unable to work?
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When the fibrous plaque is circumferential
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What is coronary artery bypass surgery?
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Diverting either an artery or vein from the aorta to the coronary artery past the site of plaque to restore adequate blood flow
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Where does the artery or vein come from in bypass surgery?
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It is an autograft transplant from another body part of the same individual
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What does double bypass surgery refer to?
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Double refers to the amount of vessels blocked that need to be bypasses (in this case two)
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What is the purpose of coronary angioplasty?
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A procedure used to open blocked or narrowed coronary arteries
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How is coronary angioplasty performed?
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A catheter is inserted with an uninflated balloon to the site of plaque. It is then inflated and this breaks up the atherosclerotic plaque
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What happens after the coronary angioplasty procedure?
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The endothelium will be damaged but this repairs usually within a week
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How has angioplasty been modified to maintain the luminal space after the procedure?
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A stent is inserted and structured in the location of the plaque - holds open tube to allow access for surgery
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What is a stent?
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It is made of biologially inert material and is a collapsible wire that is expanded by the balloon and left in the artery
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Why would you choose angioplasty over bypass surgery?
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It is much less invasive
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Why would you choose bypass over angioplasty?
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Individuals may have many plaques in the coronary arteries making angioplasty and stent implantation nearly impossible
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What happens during a myocardial infarct?
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Ischemic damage to the cardiac muscle due to complete occlusion of the coronary arteries leads to mechanical and electrical failure of cell activity
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What does the failure in mycardial cell activity lead to?
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Inadequate blood supply to the vital organs, and possible sudden death
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What does a lack of oxygen to the mitochondria of cardiac muscle cells result in?
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Decreased ATP production
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What does the decreased ATP production in cardiac myocytes result in?
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Not enough energy to support ion channels and the actin-myosin contractility system
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What is myocytolysis?
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Cells that are neighbouring those with decreased oxygen must work hard to compensate for the inability of neighbouring cells to contract-> which in turn results in hypoxic damage to these cells
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What are some symptoms of a myocardial infarct?
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Sweating, Nausea, Pain, Shortness of Breath
|
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What are four causes of myocardial infarct?
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-Thrombus
-Embolus -Hemorrhage from an atherosclerotic plaque -Spasm of coronary arteries |
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What happens with acute occlusions following minimal stenosis of the lumen?
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Infarct resulting because there isnt collateral input from other branches to supply O2 to the deprived tissue
|
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What happens with acute occlusions following gradual stenosis?
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There will be many anastomoses and extensive collateral flow and therefore minimal tissue damage
|
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How is more blood able to flow through the collateral branches to supply the ischemic tissues?
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Parts of the myocardium subjected to decreased oxygen demand will vasoconstrict, allowing increased perfusion pressure which drives more blood flow through the collateral branches to the ischemic tissues - why must one relax to decrease oxygen demand to allow this vasoconstriction to occur
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When there is occlusion of a coronary artery, why is it necessary to institute treatment right away?
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To save the ischemic zone and minimize the necrosis in the cardiac muscle
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What is characteristic about the ST segment in mycoardial infarction? How does this differ from coronary artery disease?
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The characteristic pattern of myocardial infarction is the increase in elevation of the ST segment, while that of coronary artery disease has a depressed ST segment
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How can you diagnosis MI by looking for necrotic cardiac muscle?
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Diagnostic enzymes are released from the necrotic cardiac muscle
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What is a specific marker of acute myocardial infarct?
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Troponin 1
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What does the extent of mechanical failure determine?
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The cardiac output
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What does the extent of mechanical failure depend on?
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The size and location of necrotic tissue
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What does occlusion of the upper right coronary artery result in?
|
Ischemia of the posterior wall of the left ventricle and the posterior part of the interventricular septum
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What does occlusion of the upper circumflex artery result in?
|
Ischemia of the lateral wall of the left ventricle
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What can electrical failure be easily caused by?
|
Impaired blood flow to the vital regions of the His-Purkinje system
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What can the electrical failure caused by impaired flow to the His-Purkinje system result in?
|
Cardiac arrhythmias
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What is ventricular fibrillation?
|
Uncoordinated contraction of the ventricular cardiac muscle
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What is defibrillation?
|
Passing a controlled electrical current through the heart to depolarize all the muscle, hoping that some other site of cardiac muscle may take over the pace-maker role and coordinated contractions can resume
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When must thrombolytic drugs be given to save the tissue in the ischemic zone following occlusion in the coronary arteries by a thrombus?
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4 hours
|
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When does necrosis of the zone of sustained ischemia occur?
|
8-24 hours after onset of artery occlusion
|
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When does invasion of neutrophils and macrophages occur?
|
24hrs to 3 days
|
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When do fibrocytes begin to initiate formation of scar tissue?
|
3-10 days
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Why would a thin ventricular wall develop during the healing process from a myocardial infarct?
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During the healing process, there may be a period of inadequate fibroblastic activity- and the wall is vulnerable to rupture
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What is a cardiac tamponade?
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Cardiac rupture allowing blood to fill the pericardium sac, increasing the external pressure against the heart causing inadequate filling of the ventricles and thus decreasing stroke volume
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Why is there a risk of embolus in myocardial infart?
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There may be thrombus formation on the endocardium during healing, and it can become loose
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What happens if necrosis occurs at regions of attachment for papillary muscles?
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The muscles may rupture and detach causing loss of valvular control
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What if the infarct is in the intraventricullar septum?
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There might be a defect in the septal wall causing mixing of blood from two ventricles
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What happens when a ventricular aneurysm forms after myocardial infarct?
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There is weakened tissue in the ventricular wall leading to a "bubble" that could block passage of blood leading to turbulent flow and risk of thrombus formation as well as rupture
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What is C-reactive protein?
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An opsonin that is normally relased during inflammation to react to a particular component of the bacterial mmebrane
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How do levels of C-reactive protein change in coronary heart disease?
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During wide spread inflammation like in atherosclerosis, the level of C reactive proteins increases in the blood
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Why are saturated fats bad for you?
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They increase LDL and decrease HDL thus increasing risk of atherosclerosis
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How does aspirin help in the case of myocardial infart?
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It helps to limit thrombus formation
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Where does depolarization begin?
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At the sinoatrial node
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What is the sinoatrial node?
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The pace maker of the heart
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What is the range of heart beat contractions set by the SA node?
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60-100 beats per minute
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What occurs after depolarization begins at the SA node?
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There is the coordinated contraction of the atria and the ventricles
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What separates the movement of the wave of depolarization from the atria to the ventricles?
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There is a delay of impulse transmission at the AV node
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What is so important about this delay at the AV node?
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It allows time for the ventricles to fill before they contract
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Where do impulses travel after the AV node and what does this accomplish?
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To the His-Purkinje system, allowing depolarization and thus contraction of the ventricles
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What are the other intrinsic pacemakers of the heart?
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The AV node (40-60 times per minute)
The cells in the Purkinje system, depolarize at an even slower rate |
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What is the difference between the role of the SA node and the AV node and Purkinje cells as pacemakers?
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The SA node is the fastest intrinsic pacemaker and thus drives everything else, but if it fails the back-up pace-makers come in to maintain heart beats which will keep the individual alive even though its at a slower rate
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Why are the atria and ventricles insulated from each other? What does this allow?
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This prevents leakage of the impulses from locations other than the AV node, allowing control of coordinated muscle activity in the heart
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What are four external factors that control the rate at which the SA node depolarizes?
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-Cardiovascular center input
-ANS -Noradrenaline and acetylcholine -Feedback systems |
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What are some examples of feedback systems that control the SA node depolarization rate?
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-Baroreceptors in the aorta
-Pressure receptors in the carotid arteries |
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What happens when these systems send info to the CNS?
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It alters the rate of SA depolarization basd on the demand
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What does the P wave on the EKG represent?
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Atrial depolarization
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What does the QRS wave on the EKG represent?
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Ventricular depolarization
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What does the T wave on the EKG represent?
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Ventricular repolarization
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What is bradycardia?
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Slow heart rate, less than 50 bpm
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What is an example of physiological Bradycardia?
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Athletic hearts can have physilogical hypertrophy and can have a larger cardiac output, therefore requiring less contractions per minute at equal conditions
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When would pathological bradycardia occur?
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When the SA node malfunctions
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What does pathologcial bradycardia lead to?
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Inadequate supply of oxygen and nutrients to vital organs
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What is tachycardia?
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Rapid heart rate, >90 bpm
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What can bpm increase to during exercise that is normal?
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~190bpm
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Why does bpm increase during an emotional state?
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There is the release of adrenaline which activates the sympathetic nervous system to increase the heart rate
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When would pathological tachycardia occur?
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Fevers, hyperthyroidism, decrease in blood pressure
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What is sinus arrythmia?
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A harmless condition in which heart rate increases slightly with inhalation and decreases slightly with exhalation
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What is the EKG pattern of someone with a heart block?
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See only P waves
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Why would you see only P waves in this patient with heart block?
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Depolarization of the atria is occuring, but the impulse is not being conducted to the ventricles so you don't see and depolarization here
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What does the EKG look like in the case of fibrillation?
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There is no coordinated contraction and thus no cardiac output
-Do not observe a QRS complex |
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What happens if the conduction block is prolonged?
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Back-up pacemakers may attempt to take over
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What is an ectopic focus?
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When a damaged region of the heart is generating impulses and taking over pace-making activity when it should not be
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What is circus re-entry?
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If there is a damaged area of the heart that casuses slower than normal impulses, the impulse direction will change to a circular movement
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Why are artificial pacemakers useful?
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-They are capable of adapting
-They can allow SA node to function and take over as soon as it malfunctions |
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What is the contraction like in someone with ATRIAL ARRYTHMIA?
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There are two types: 1) flutter- the atria are contracting in a coordinated manner but at a very high rate, up to 200-400 contractions per minute
2) fibrillation: no coordinated contractions |
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What is the problem with this increased contraction rate during atrial arrythmia?
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This is too fast for the ventricles to keep up
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Why can the individual survive in atrial arrythmia?
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-The ventricles can still fill passively upon valve opening
-Ventricles can also start their own pace-making systems |
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What are individuals with atrial arrythmia at increased risk for?
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Thrombus formation on the endocardium
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Why is ventricular arrythmia more critical than atrial arrythmia?
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Ventricular arrythmia has NO cardiac output and thus the body is not supplied with oxygen
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What are the types of valves in the heart?
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2 atrioventricular valves
2 semilunar valves to great vessels |
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What are the two atrioventricular valves?
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Bicuspid (Left atria to Left ventricle)
Tricuspid (Right atria to right ventricle) |
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What are the two semilunar valves?
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Pulmonary (RV to pulmonary artery)
Aortic (LV to aorta) |
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What are the two main problems of the valves?
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Stenosis
Regurgitation |
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What is stenosis?
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The valves are not opening properly, and the narrow lumen is limiting blood flow
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What can stenosis of valves be caused by?
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Calcification preventing complete opening of the valves
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What is regurgitation caused by?
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The valves are incompetent and cannot close properly, leading to back flow
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What is the initial cause of rheumatic heart disease?
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Beta-hemolytic streptococci
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What is a severe consequence of the infection?
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There might be antibodies produced against the bacteria that can cross-react with glycopeptides on self tissue of the individual
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How does inflammation in the heart result during rheumatic heart disease?
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Antibodies are reacting against the joints and other tissues including the heart valves of the individual
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What can the damages of the heart valves lead to?
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Stenosis or regurgitation
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What is a result of the stenosis and regurgitation of valves?
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Decreased flow, increased workload of the heart
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What is fungal endocarditis an example of?
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When pathogens can cause direct damage to the heart valves
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What is a typical adaption of the heart in valvular heart disease?
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The heart undergoes hypertrophy to maintain cardiac output
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When do symptoms of valvular heart disease appear?
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Only when advanced stenosis or regurgitation has taken place
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What happens in aortic stenosis?
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The left ventricle will hypertrophy
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What is syncope?
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A symptom of aortic stenosis, the individual faints due to inadequate oxygen supply
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What can eventually happen as a result of aortic stenosis?
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Ischemia of cardiac muscle tissue
Angina |
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What happens in aortic regurgitation?
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There is back flow into the ventricle
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What does the ventricle do to compensate?
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It dilates (according to Starling's law) in order to have more forceful contractions to expel the increased blood
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What happens when the ventricle is no longer able to compensate?
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-Inadequate blood flow leading to dypsnea, fatigue, and increased workload in the left atrium
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What can increased workload lead to?
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Problems in the pulmonary circulation
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What happens during mitral stenosis?
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The left atrium cannot pump blood efficiently to the left ventricle
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How does mitral stenosis affect the RIGHT ventricle???
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When the pressure in the left atrium increases, the atrium will dilate, resulting in an increased pressure in the pulmonary circulation (since LA and pulmonary veins are connected), which will create a need for the RIGHT ventricle to pump harder to get blood from the right ventricle to the pulmonary circulation
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What does mitral stenosis lead to?
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Fatigue, dypsnea
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What is mitral regurgitation?
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Backward flow into the left atrium
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What happens when the blood flows back into the left atrium?
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Blood goes into the pulmonary circulation (back through veins), resulting in fluid being forced into the lungs
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What happens as a result of fluid being forced into the lungs?
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Edema
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Which chambers of the heart are affected by the increased workload?
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The left ventricle, left atrium, and right ventricle hypertrophy and dilate
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What is heart failure?
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The heart is no longer able to deliver an adequate cardiac output to supply tissue demand
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What is congestive heart failure accompanied by?
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Edema (in the periphery and lungs)
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What is heart failure caused by?
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Increasing the workload of the heart as a result of inefficient pumping action, and the heart is no longer able to cope with the large workload
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What are four diseases that typically result in heart failure?
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Coronary heart diseases
Hypertension Valvular diseases Arrythmias |
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How does coronary heart disease result in congestive heart failure?
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Damage to pump (heart) itself
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How dose hypertension result in congestive heart failure?
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Increased workload because of having to pump against an increased resistance
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How does edema come about in congestive heart failure?
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The heart isn't pumping out enough, therefore there is a back up in the veins leading to tissue and lung swelling
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How do chronic lung diseases sometimes result in congestive heart failure?
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Chronic lung diseases can cause an increase in pulmonary pressure increasing the workload of the heart
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How do valvular diseases result in congestive heart failure?
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There is inefficient blood flow
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How does arrythmia result in congestive heart failure?
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There is electrical failure for coordinated efficient contractions
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What are some adaptive mechanisms of the body to increase cardiac output?
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-Dilation
-Hypertrophy -Tachycardia |
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How does the kidney attempt to compensate for decreased blood flow?
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Increases retention of salt and water in the body
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What is a consequence of this retention of salt and water in the body?
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Increase in blood pressure
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What are some symptoms of congestive heart failure?
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Edema
Dyspnea Cyanosis Orthopnea Fatigue Nocturia |
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What is dyspnea a result of?
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Pulmonary Edema
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What is cyanosis?
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Change in coloration as a result of inadequate oxygen supply
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What is orthopnea?
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Shortness of breath especially lying down (increased distribution of the blood to the lungs)
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What is nocturia?
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When lying down, workload for heart decreases, so kidney excrete excess fluids it retained during the day-> increased need to urinate!
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How do you treat heart failure?
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Treat the factors that caused it
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What is cor pulmonale?
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Right sided heart failure, an enlargement of the right ventricle due to high pressure in the lungs caused by chronic lung disease
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What is a stroke?
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An infarct in the brain caused by occlusion of an artery in the brain that led to tissue necrosis
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What are the two main supplies of blood to the brain?
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Carotid arteries
Vertrebral arteries |
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How are the carotid arteries and vertebral arteries connected?
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By the Circle of Willis
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What type of necrosis does infarct usually result in?
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Liquefactive necrosis
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What percentage of cardiac output is sent to the brain?
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20%
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What is the max survival time when the brain is deprived of oxygen?
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5-6 minutes
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What is the most common cause of stroke?
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Thrombotic infarction
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Where does atherosclerosis tend to occur in the brain arteries?
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In major bifurcations, especially around the circle of willis
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What can the systemic blood pressure be without affecting cerebral blood flow?
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anywhere from 60mm -160 mm
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How is the cerebral blood flow kept so constant?
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Autoregulation, careful control
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What is an intracerebral hemorrhage caused by?
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A micro-aneurysm in the brain vasculature
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What are common sites of a "Berry aneurysm"?
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Around the circle of Willis
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What can rupture of the Berry aneurysm lead to?
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Tissue necrosis or stroke
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What happens if there is a saccular aneurysm in the brain?
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It will result in subarachnoid hemorrhage
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What are some subsequent problems of subarachnoid hemorrhage?
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-Vasoactive compounds are released as a result of breakdown of blood components
-This could lead to local arterial spasm and further tissue damage |
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What do the consequences of stroke depend on?
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The SITE of tissue damage
The EXTENT of tissue damage The COLLATERAL circulation |
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What are some consequences of stroke?
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Speech impairment and language
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How can proximal occlusion be bypassed?
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By collateral flow from the Circle of Willis
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What is the most frequent site of impaired blood flow?
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The middle cerebral artery
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What does the impairment of blood flow to the middle cerebral artery result in?
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Effects the contralateral (opposite) site of the body
Impaired speech |
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What is hemiplegia?
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Paralysis (on one side of body)
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What is hemianethesia?
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Impairment of sensation (on one side of body)
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What are two ways that function can be returned?
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1-recovery of ischemic zones with collateral circulation
2- learning and adaption even in necrotic zones |
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What is multi-infarct dementia?
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Due to the cumulative effect of many tiny hemorrhages in the brain in many regions
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