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30 Cards in this Set
- Front
- Back
Define cardiac output
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stroke volume x heart rate; rate of O2 consumption/(arterial O2 content - venous O2 content)
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Define mean arterial pressure
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cardiac output x total peripheral resistance; 2/3 diastolic pressure + 1/3 systolic pressure
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Define pulse pressure
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systolic pressure - diastolic pressure; proportional to stroke volume
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Define stroke volume
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CO/HR; EDV-ESV
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Define preload
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ventricular EDV
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Define afterload
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MAP (proportional to peripheral resistance)
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Define ejection fraction. What is normal?
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index of ventricular contractility; SV/EDV; (EDV-ESV)/EDV; > or = 55%
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Define change in pressure
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flow x resistance
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Define resistance
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(8n (viscosity) x length)/ (pi x r^4)
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Define capillary pressure
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pushes fluid out of capillary
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Define interstial fluid pressure
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pushes fluid into capillary
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Define plasma colloid osmotic pressure
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pull fluid into cavity
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Define interstitial fluid colloid osmotic pressure
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pulls fluid out of capillary
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Define net filtration pressure
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(capillary pressure - interstitial fluid pressure) - (plasma colloid pressure - interestial fluid colloid osmotic pressure)
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Define net fluid flow
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net filtration x filtration constant
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Stroke volume is increased with
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increased contractility, decreased afterload, increased preload; anxiety, exercise, pregnancy
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Contractility and stroke volume increases with
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Catecholamines, increased intracellular calcium, decreased extracellular sodium, digitalis
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Contractility and stroke volume decrease with
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Beta1 blockade, heart failure, acidosis, hypoxia/hypercapnea, non-dihydropyridine Ca2+ channel blockers
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Myocardial O2 demand increases with
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Increased afterload, increased contractility, increased heart rate, increased heart size, increased wall tension
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What is the effect of exercise on cardiac output
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CO initially increases because of an increase in stroke volume. After prolonged exercise, CO increases because of an increased heart rate.
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How can you increase preload?
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Slight increases with exercise, increased blood volume, sympathetics
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List the phases of left ventricular contraction
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1. Isovolumetric contraction; 2. Systolic ejection; 3. Isovolumetric relaxation; 4. Rapid filing; 5. Reduced filling
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Which phase of ventricular contraction has the highest rate of O2 consumption?
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Isovolumetric contraction
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What is responsible for resistance in the cardiovascular system?
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Arterioles = most of total peripheral resistance
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What pathology increases viscosity?
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Polycythemia, Hyperproteinemic states (eg multiple myeloma), Hereditary spherocytosis
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What causes edema?
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1. increased capillary pressure (heart failure); 2. decreased plasma proteins (nephrotic syndrome, liver failure); 3. increased capillary permeability (toxins, infections, burns); 4. interstitial fluid coloid osmotic pressure (lymphatic blockage)
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Define 'a' wave
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JVP: Atrial contraction
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Define 'c' wave
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JVP: RV contraction
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Define 'v' wave
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JVP: Increased atrial pressure due to filling against closed tricuspid valve
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List the characteristics of cardiac myocyte cells
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Calcium-induced calcium release, plateau due to Ca2+ influx, automaticity, gap junctions creating electric coupling between cardiac myocytes
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