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62 Cards in this Set
- Front
- Back
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Right arm and left leg
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Lead II
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Right arm and left arm
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Lead I
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Right arm, central terminal using reistors, left arm/leg
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aVR
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Left arm and a central terminal using resistors, right arm and left leg
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aVL
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Which ECG leads is bipolar
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lead III
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Nodal Rhythm
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Ventricular conduction pattern is normal but its relationship with the P wave is not
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Sinus Rhythm
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a P wave and an isoelectric line will precede each R wave; R wave would be of longer duration and the T wave would usually be inverted
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What might a prolonged PR segment be caused by
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Increased parasympathetic tone to the AV node;
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What would reflexively happen in the case of decreased carotid sinus pressure
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Decreased parasymp tone and increased symp tone
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At what point in the ECG is the beginning of the hearts refractory period
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Beginning of the QRS complex
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Where in the ECG is the first heart sound heard
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Begins during the QRS complex and ends before the beginning of the T wave
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PR interval is representative of what
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atrial systole
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Inverted P wave indicates what
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retrograde conduction, often due to a nodal rhythm (where AV node takes over pacemaker activity for SA node)
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Decreased ST segment
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Early repolarization of the ventricular fibers
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Incresed R-R interval
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Depression of the SA node; could cause an ectopic rhythm
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Prolonged PR segment
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Slowed conduction at the AV node (increased parasymp tone)
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Prolongation of the QRS complex
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Conduction block in either bundle branch
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An independence of the P wave and of the QRS complex of the ECG indicates what
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Failure of the AV node to conduct
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Can aldosterone produce hyperkalemia?
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No; it facilitates the loss of K from the body in urine and sweat
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How might you cause a cardiac Purkinje fiber to depolarize during phase 4 of the transmembrane potential
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Decreasing its K+ conductance; you could also increase its Na or Ca conductance (NE increases heart rate by increasing Ca in the pacemaker cell)
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This ion's gate opening initiates the fast current
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Na
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This ions gate opening initiates the slow current
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Ca
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This ions gate opening is responsible for repolarization or hyperpolarization of the membrane
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K
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Vessel radius narrows by 50%; what is the expected change in blood flow through the stenotic artery
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Decreased to 1/16th
Radius decreased by (1/2)^4 = 1/16 |
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Equation for TPR
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dP/Q
Q = flow = CO |
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Where is systolic blood pressure the highest?
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Renal artery
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Increased ejection fraction = a decrease in EDV or ESV
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ESV; increased EF means more of the EDV is being ejected and thus less is left at the end of systole
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How would an extrasystolic beat affect pulse pressure and why
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There would be an increased pulse pressure bc the contractility of the ventricle is increased due to extra Ca influx during the extrasystolic beat
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Blood viscocity and turbulance
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Low blood viscocity (decreased hematocrit/anemia) = increased turbulance
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How would an acute decrease in arterial blood pressure affect the firing rate of the carotid sinus nerve
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Decreased firing rate; decreased bp causes decreased stretch of the carotid sinus baroreceptors and decreased firing of the carotid sinus nerve
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Why do skeletal muscle arterioles dilate during exercise
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Local metabolites; acts to decrease TPR (even though theere is constriction in other places muscles contribute a karge fraction to TPR)
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What occurs in the aortic pressure tracing at the dicrotic notch
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Aortic valve closure
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arterial pressure equation
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MAP = CO x TPR
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Cardiac Ouput by the Fick Principle
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CO = 02 consumption/(02 in pulmonary vein - 02 pulmonary artery)
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HR = 70
Pulm vein 02 = .24 PUlm art 02 = .16 Whole body 02 consumption = 500 ml Cardiac output? |
Fick principle:
CO = 02 consumption/(02 in pulmonary vein - 02 pulmonary artery) CO = 500/(24-16) = 6.25 L/min |
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Ion responsible for upstroke in everything but nodes
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Na
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Ion responsible for upstroke in nodes
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Ca
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Ion responsible for plateau in ventricular action potential
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Slow Ca influx
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Right atrial pressure can be used interchangably with what
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end diastolic volume
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What is the site of highest resistance in the vasculature?
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Arterioles
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Relationship of resistance to pressure
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dP = Q x R
Greater the resistance is, the greater the decrease in pressure |
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Pulse presusre
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Systolic - diastolic
It reflects the volume ejected by the left ventricle (stroke volume). Pulse pressure increases when the capacitance of the arteries decreases (aging) |
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In the SA node, what causes phase 4 depolarization
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An increase in Na conductance which depolarizes the membrane; phase 4 is responsible for the pacemaker properties of the SA node;
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A1 Receptors
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NE receptors; excitatory on vascular smooth muscle and cause vasoconstriction
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When is aortic pressure highest
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Right at the beginning of reduced ventricular ejection
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What does histamine do
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Causes vasodilation of the arterioles, which increases Pc and capillary filtration; it also causes venous constriction which contributes to increased Pc
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Most important vasodilators for the brain
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PC02
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Most important vasodilators for the heart
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adenosine and hypoxia
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Is blood flow to the skin regulated more by sympathetics or local mediators
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Sympathetics
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Why does exercise cause a vasodilation of skeletal muscle arterioles despite sympathetic outflow
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Overriding vasodilatino due to the buildup of vasodilator metabolites (lactate, K, adenosine); this improves the delivery of 02 to be used by contracting muscles
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When propranolol is administered, blockade of which receptor is responsible for the decrease in cardiac output that occurs?
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B1 Receptors and B2 receptors; to reduce cardiac output, it inhibits B1R in the SA node (heart rate) and in ventricular muscle (contractility)
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During what phase of the cardiac cycle is ventricular volume lowest?
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Isovolumetric ventricular relaxation
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What factors determine myocardial 02 consumption
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the amount of tension developed by the heart
it increases w increase in aortic pressure (afterload); increase in heart rate or stroke volume (incrased CO); or when the size (radius) of the heart is increased (T = P x r) |
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Pheochromocytoma
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increased circulating levels of catecholamines, whcih increases bp by their effects on the ehart (increased HR and contractility) and blood vessels (vasoconstriction)
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Which part of the cardiac AP is the trigger to release Ca from the SR for contraction
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Plateau of the ventricular action potential; transient Ca permeability increase
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Which phase of the ventricular AP coincides with diastole
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Phase 4 is ventricular diastole
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Which receptor mediates slowing of the heart
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Muscarinic receptors + acetylcholine from PSNS
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Negative Ionotropic Effect
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Decreases contractility, which is the ability to develop tension at a fixed muscle length
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Factors which decrease contractility
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Decreased intracellular Ca2+
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How do cardiac glycosides increase heart rate
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increase intracellular Ca2+ by inhibiting the NA-K+ pump and thereby inhbiiting Na-Ca exchange (which pumps Ca out of cell normally)
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Where are cardiac gap junctions located
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Intercalacated disks; are low resistance sites for electrical spread
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end diastolic volume equation
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stroke volume/ejection fraction
CO = SV x HR |
