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29 Cards in this Set
- Front
- Back
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The cardiac action potential originates in a group of cells called the _____
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SA node
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The cells in the SA node can spontaneously or automatically ________ and produce an _______ at a regular rate.
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Depolarize, action potentail
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Two factors that are the determinants of the cell-cell conduction of the cardiac action potential are:
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Low electrical resistance of the gap junction; voltage difference between the cells
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Electrical synapse with very low electrical resistance and the best place to conduct the AP
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Annoxins (gap junctions)
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Voltage difference drives the electrical:
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Current flow
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Basis of the EKG is the:
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Outside current
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Stage 0-2 if called the:
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Effective refractory period
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SA node and the AV node have only ___ phases of the cardiac action potential
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3
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Name the phases of the AP that SA and AV node cells have.
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0,3,4
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Name the two inward currents that cause phase 0 in AV and SA nodal cells.
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Ca, f
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Abnormality of impulse formation and conduction in cardiac myocytes.
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Arrhythmia
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Length of the cardiac cycle.
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0.8 s, 75 bpm
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Inlet valves open, outlet valves closed and ventricular filling occurs.
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Inflow phase
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All valves closed, no blood flow, heart contracts.
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Isovolumetric contraction phase
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Inlet valves closed, outlet valves open, blood flows into aorta and pulmonary artery.
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Outflow phase
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All valves are closed, no blood flow, heart relaxes.
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Isovolumetric relaxation phase
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Abnormality of E-C coupling reduces:
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Cardiac contractility
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E-C coupling is enhanced by drugs for tx of:
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Heart failure
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____ has a key role in E-C coupling
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Intracellular Ca++
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B-blocker, Ca++ channel blockers, and nitrates are all given to tx:
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Angina pectoris
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Most common cause of CAD.
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Atherosclerosis
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Increases SBP
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Increased SV
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Increases both SBP & DBP
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Increased HR
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Elevates DBP
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Increased peripheral resistance
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Moment to moment control of BP
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Baroreceptors
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Counteract increased MAP
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Bradycardia and vasodilation
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Baroreceptors send info up to the ______.
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Medulla
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Baroreceptors work by a:
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Neg feedback loop
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Long term control of BP is by:
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Renal regulation of ECF volume
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