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15 Cards in this Set
- Front
- Back
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what is the role of the cardiovascular system?
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supplies most tranport needs of the body - delivery of oxygen, substrates and hormones and removal of metabolic end products
maintain pH and core temperature |
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how is cardiac output distributed at rest and during exercise?
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control of CVS is toward maintaining BP and meeting the tissues metabolic needs which is done by increasing cardiac output
during exercise Q and blood flow increase to meet nutrient and oxygen needs |
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what are the main characteristics of myocardial cells? (7)
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inherent rythmicity
contractile cells and electrical cells involuntary one or two nuclei as opposed to many in skeletmal muscle fibers extensive capillarisation mitochondria occupy 40% of cytoplasm volume joined by intercalated disks |
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what is the electrical conduction system of the heart?
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sa node - av node - av bundle - bundle branches - purkinje fibers
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what are the main quantative parameters of the cardiac cycle?
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atrial systole=.15s
atrial diastole=.65s ventricle systole=.3s ventricle diastole=.5s stroke volume=amount of blood pumped per cycle EF=0.67 EDV=125mL ESV=42mL cardiac output=HRxSV 5L/min at rest, 20-35L/min during exercise |
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what does the ECG reflect of the cardiac cycle?
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depolarization/repolarization of cardiac cell membrane - SL
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changes in heart with endurance training? (5)
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decreased resting and submaximal heart rate
increased stroke volume altered ECG increased prevalence of 3rd and 4th heart sounds improved calcium release and transport |
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preload - what is the Frank-Starling Mechanism and what is it measured by?
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stroke volume + myocardial stretch which determines end diastolic pressure
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what are the factors that increase(3) and decrease (3) preload?
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increases due to - mitral insufficiency, increased BV, drugs that cause vasoconstriction
decreases due to - mitrol stenosis, decreased BV, drugs that cause vasodilation |
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what is the law of laplace?
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tension = pressure x radius/2
anything that causes increase in linear dimensions of the heart with increase heart's energy requirements |
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what is CV drift?
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decreased venous return with prolonged exercise cause an SV decrease
due to SNS control mechanisms and/or redistribution of blood to skin for cooling |
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what is afterload?
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resistance to ventricular emptying
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what determines afterload?
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EDV - increases in next cardiac cycle with decreased SV, SV increases at higher pressure than normal - with weight lifting
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what is the Valsalva maneuver?
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increases intrathoracic pressure in afterload
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what factors affect contractility of the heart?
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contractility of the myocardium depends on calcium availability
with training - increased SR function and increased myosin ATPase - strength of contraction catecholamines and sympathetic activity increase contractility |
