Cardio Phys Review Flashcards
(37 cards)
The ____ interval on EKG represents initial depolarization of the ventricle and increases in conditions such as heart block
PR
The ST segment is isoelectric and represents the period when the ventricles are ________
Depolarized
The resting membrane potential for cardiac action potentials is determined by conductance to _____
K+
[maintanence is by Na/K ATPase]
Phases of ventricular action potential and their associated changes in ion conductance
Phase 0 = Na+ in [depolarization]
Phase 1 = slight K+ out, decrease in Na conductance [initial repolarization]
Phase 2 = Ca++ in, increased K+ conductance [plateau — inward current = outward current]
Phase 3 = K+ out, decreased Ca conductance [repolarization]
Phase 4 = resting potential ~ K+ equilibrium potential [inward current = outward current]
Phases of SA node action potential and their associated changes in ion conductance
Phase 0 = Ca++ in [rapid depolarization]
Phase 3 = K+ out [repolarization]
Phase 4 = Na+ leaks in [slow depolarization]
Phases 1 and 2 not present in SA node APs
Preload corresponds to the _______ volume, which is related to the ______ pressure
End-diastolic; right atrial
[thus when venous return increases, EDV increases and stretches/lengthens the ventricular muscle fibers]
Afterload for the left ventricle is the _____ pressure
Aortic
[increases in aortic pressure cause an increase in afterload on the left ventricle]
Afterload for the right ventricle is the _____ pressure
Pulmonary artery
[increases in pulmonary a. pressure cause an increase in afterload on the right ventricle
_____ length determines the maximum tension or force of contraction in cardiac muscle
Sarcomere
The velocity of contraction at a fixed muscle length is maximal when the afterload is ______
It is ______ by increases in afterload
Zero
Decreased
Increased preload results in a _______ in stroke volume, and thus a _____ in width of the pressure-volume loop
Increase; increase
[opposite is true for increased afterload]
Calculation and normal value for ejection fraction
Ejection fraction = stroke volume/EDV
Normally 55%
Isovolumetric ventricular contraction begins after the onset of the _______ on EKG
QRS wave
The onset of the _______ on EKG marks the end of both ventricular contraction and rapid ventricular ejection
T wave
If the EF increases, there will be a decrease in:
A. Cardiac output B. ESV C. HR D. Pulse pressure E. Stroke volume F. Systolic pressure
B. ESV
When EF increases, a higher fraction of the EDV is ejected in the stroke volume. When this situation occurs, the volume remaining in the ventricle after systole (ESV) will be reduced
An ECG on a person shows ventricular extrasystoles. The extrasystolic beat would produce:
A. Increased pulse pressure because contractility is increased
B. Increased pulse pressure because HR is increased
C. Decreased pulse pressure because ventricular filling time is increased
D. Decreased pulse pressure because stroke volume is decreased
E. Decreased pulse pressure because the PR interval is increased
D. Decreased pulse pressure because stroke volume is decreased
An ECG on a person shows ventricular extrasystoles. After an extrasystole, the next “normal” ventricular contraction produces:
A. Increased pulse pressure because the contractility of the ventricle is increased
B. Increased pulse pressure because TPR is decreased
C. Increased pulse pressure because compliance of veins is decreased
D. Decreased pulse pressure because the contractility of the ventricle is increased
E. Decreased pulse pressure because TPR is decreased
A. Increased pulse pressure because the contractility of the ventricle is increased
An increase in contractility is demonstrated on a Frank-Starling diagram by
A. Increased cardiac output for a given EDV
B. Increased cardiac output for a given ESV
C. Decreased cardiac output for a given EDV
D. Decreased cardiac output for a given ESV
A. Increased cardiac output for a given EDV
The ventricles are completely depolarized during which isoelectric portion of the ECG?
A. PR interval B. QRS complex C. QT interval D. ST segment E. T wave
D. ST segment
A 30 y/o female’s ECG shows 2 P waves preceding each QRS complex. The interpretation of this pattern is:
A. Decreased firing rate of the pacemaker in the SA node
B. Decreased firing rate of the pacemaker in the AV node
C. Increased firing rate of the pacemaker in the SA node
D. Decreased conduction through the AV node
E. Increased conduction through the His-Purkinje system
D. Decreased conduction through the AV node
A pattern of two P waves preceding each QRS complex indicates that only every other P wave is conducted through the AV node to the ventricle. Thus, conduction velocity through the AV node must be decreased
Which of the following is the result of an inward Na+ current?
A. Upstroke of the AP in the SA node
B. Upstroke of the AP in purkinje fibers
C. Plateau of the AP in ventricular muscle
D. Repolarization of the AP in ventricular muscle
E. Repolarization of the AP in the SA node
B. Upstroke of the AP in purkinje fibers
In the SA node, phase 4 depolarization (pacemaker potential) is attributable to:
A. An increase in K+ conductance B. An increase in Na+ conductance C. A decrease in Cl- conductance D. A decrease in Ca+ conductance E. Simultaneous increases in K+ and Cl- conductance
B. An increase in Na+ conductance
During which phase of the cardiac cycle is aortic pressure highest?
A. Atrial systole B. Isovolumetric ventricular contraction C. Rapid ventricular ejection D. Reduced ventricular ejection E. Isovolumetric ventricular relaxation F. Rapid ventricular filling G. Reduced ventricular filling (diastasis)
D. Reduced ventricular ejection
Aortic pressure reaches its highest level immediately after the rapid ejection of blood during left ventricular systole. This highest level actually coincides with the beginning of the reduced ventricular ejection phase
During which phase of the cardiac cycle is ventricular volume lowest?
A. Atrial systole B. Isovolumetric ventricular contraction C. Rapid ventricular ejection D. Reduced ventricular ejection E. Isovolumetric ventricular relaxation F. Rapid ventricular filling G. Reduced ventricular filling (diastasis)
E. Isovolumetric ventricular relaxation
