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45 Cards in this Set
- Front
- Back
Two primary purposes of the CV system?
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1) Facilitate exchange of substances and energy between cells and external environment
2) Removal of metabolites |
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By what mechanism does the heart pump the blood?
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Pressure my nigga
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Cardiac output must = ?
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Return
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3 "pump variables?"
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1) Cardiac output
2) Stroke volume 3) Frequency |
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Of the 3 pump variables which tends to stay fairly consistent?
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Cardiac output ~ 5l/min for a 70kg male
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Location of the SA node?
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Superior right atrium
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Location of AV node?
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Kind of between the right atrium, right ventricle and left ventricle.
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Out of all the conduction pathways which has the highest and the lowest intrinsic rate?
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SA node = highest
Purkinje fibers = lowest |
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Intrinsic rate of the SA node?
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~ 100bpm
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Intrinsic rate of the AV node?
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40 - 60 BPM
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Intrinsic rate of the Purkinje Fibers?
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30-40 BPM
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Portion of the nervous system responsible for slowing heart rate?
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Parasympathetic via the Vagus nerve with release of ACh.
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Bundle of HIS sends current where?
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Apex and surface of heart
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Shortest time of depolarization?
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AV node = .05 m/sec
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Longest time of depolarization?
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Purkinje Fibers = 4.0 m/sec
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List the sequence of firing of the Atrial muscle, the Purkinje Fibers and the Ventricle
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1) Atrial muscle < 200ms
2) Purkinje muscle <300ms 3) Ventricular muscle ~ 300ms |
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Which has the larger hyperpolarization between the SA node and the AV node?
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SA node
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Depolarization of muscles/fibers faster or slower than nodes?
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Faster (virtually no slope)
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Apx depolarization threshold for nodes?
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-55mV
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Apx depolarization threshold for muscles/fibers?
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-80mV
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Steep depolarization of cardiac muscle is d/t?
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Na coming into the cell
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Transient repolarization is driven by?
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Ca coming in
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Plateau is driven by?
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Ca (Coming in less???)
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Repolarization is driven by?
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K+ leaving cell
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Resting potential is driven by?
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Lean current
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Primary difference between the AP of the ventricular muscle and the SA node?
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The depolarization of the SA node (phase 0) is driven by Ca and not Na (as it is in the muscle)
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Which has the faster funny current, parasymp or symp?
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Sympathetic
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Factors that increase SA node firing rate?
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1) Symp stimulation
2) Muscarinic receptor antagonist 3) B agonists 4) Hyopkalemia 5) Hyperthyroidism |
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Factors that decrease SA node firing rate?
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1) Parasymp stim
2) Muscarinic receptor agonists 3) B-blockers 4) Hyperkalemia 5) Na and Ca channel blockers |
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Component of cardiac cycle that includes: Ventricular relaxing, ventricular filling and atrial contraction?
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Diastole
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Component of cardiac cycle that includes: Ventricular contraction and ventricular ejection?
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Systole
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Apx how much time of the cardiac cycle is spent in diastole at a HR of 75?
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500ms
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Apx how much time of the cardiac cycle is spent in systole at a HR of 75?
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300ms
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Where is a pulmonary catheter typically inserted?
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Jugular V.
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2 cardiac output equations?
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1) CO (L/min) = HR (beats/min) x SV (L/beat)
2) CO (L/min) = (MAP [mmHg] - CVP [mmHg])/ SVR (RU) |
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SVR?
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System Vascular Resistance = Resistance to blood flow by all systemic vasculature EXCEPT pulmonary vasculature
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CVP?
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Central Venous Pressure = Describes the BP in the Thoracic Vena Cava - important b/c it determines the filling of the right ventrical
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Methods to measure CO in humans?
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1) EKG / Doppler US
2) Angiography / Radionuclide Angio 3) MRI/CT 4) Thermodilution / dye dilution 5) Fick method |
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Doppler uses US to determine...
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Direction and Velocity of flow.
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Tricuspid valve sits where?
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Between R atrium and ventrical
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Mitral valve sits where?
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Between the L atrium and ventrical
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MUGA scane?
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Multi-unit Gate Aquisition
- Uses a GAMA scanner - Measures resting cardiac performance - Radioactively tagged blood |
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Two purposes served by Echo + Thermodilution
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1) Measures change in temp in different chambers and vessels
2) Measures flow |
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LVEDV - LVESV = ?
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Stroke Volume
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Ejection fraction = ?
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SV/LVEDV (norm >= 55%)
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