Term
| cardiac conduction system |
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Definition
| group of specialized, highly excitable cells that give the heart its rhythmicity |
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Term
| function of cardiac conduction system |
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Definition
| spontaneously generates and conducts action potentials |
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Term
| sinoatrial node (description) |
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Definition
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Term
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Definition
| spontaneously generates action potentials at a rate of 70 to 80 per minute |
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Term
| SA node spreads action potentials to |
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Definition
1) cardiac muscle of atria via internodal pathways
2) to AV node via internodal pathways |
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Term
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Definition
| receives action potentials from SA node |
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Term
| AV node spreads action potentials to |
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Definition
| AV bundle/Bundle of His after the 110 ms delay |
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Term
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Definition
| divides into left and right bundle branches (one per ventricle) |
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Term
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Definition
| receives action potentials from AV node |
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Term
| AV bundle spreads action potentials to |
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Definition
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Term
| function of Purkinje fibers |
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Definition
| receive action potentials from the AV bundle |
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Term
| Purkinje fibers spread action potentials to |
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Definition
| cardiac muscle of the ventricles |
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Term
| ectopic pacemaker (description) |
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Definition
| any part of the heart other than the SA node that generates a rhythm |
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Term
| most common ectopic pacemaker |
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Definition
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Term
| heart rate if AV node is pacemaker |
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Definition
| 40 to 60 beats per minute |
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Term
| heart rate if Purkinje fibers are pacemaker |
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Definition
| 25 to 45 beats per minute |
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Term
| arrangement of cardiac muscle cells |
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Definition
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Term
| cardiac muscle cells make up |
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Definition
| the bulk of the atrial and ventricular walls |
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Term
| resting Vm of cardiac muscle cell |
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Definition
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Term
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Definition
| recording of electrical activity of cardiac muscle |
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Term
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Definition
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Term
| function of standard bipolar limb leads |
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Definition
| measure electrical activity of heart in a frontal plane |
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Term
| (standard bipolar limb lead) Lead I |
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Definition
| measures electrical activity across heart at 0° angle |
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Term
| (standard bipolar limb lead) Lead II |
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Definition
| measures electrical activity across heart at +60° angle |
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Term
| (standard bipolar limb lead) Lead III |
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Definition
| measures electrical activity across heart at +120° angle |
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Term
| augmented unipolar limb leads |
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Definition
| measure electrical activity of the heart in a frontal plane |
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Term
| (augmented unipolar limb leads)aVR |
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Definition
| measures electrical activity across heart at -150° angle |
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Term
| (augmented unipolar limb leads)aVL |
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Definition
| measures electrical activity across heart at -30° angle |
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Term
| (augmented unipolar limb leads)aVF |
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Definition
| measures electrical activity across heart at +90° angle |
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Term
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Definition
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Term
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Definition
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Term
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Definition
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Term
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Definition
| right arm to the joining of left arm and left leg |
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Term
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Definition
| left arm to the joining of left leg and right arm |
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Term
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Definition
| left leg to the joining of right arm and left leg |
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Term
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Definition
| measure the electrical activity of the heart in a transverse plane |
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Term
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Definition
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Term
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Definition
| signifies atrial deploarization; normally 80 to 120 msec in duration |
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Term
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Definition
| signifies ventricular depolarization; normally 60 to 100 msec in duration |
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Term
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Definition
| signifies ventricular repolarization; normally 160 to 200 msec in duration |
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Term
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Definition
| from onset of atrial depolarization to onset of ventricular depolarization (P to Q); normally 120 to 200 msec in duration |
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Term
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Definition
| average of all the instantaneous mean electrical vectors occurring sequentially during depolarization of the ventricles |
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Term
| mean electrical axis is based on |
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Definition
| QRS complexes of limb leads I, II, III |
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Term
| normal value of mean electrical axis |
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Definition
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Term
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Definition
| conditions where electrical activity is irregular |
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Term
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Definition
| heart rate above 100 beats per minute |
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Term
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Definition
| heart rate below 60 beats per minute |
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Term
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Definition
| elevated body temp, excessive sympathetic stimulation |
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Term
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Definition
| excessive parasympathetic stimulation; athletic heart |
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Term
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Definition
| conduction of action potential is slowed; prolonged PQ interval (greater than 200 msec) |
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Term
| type I second degree heart block |
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Definition
| conduction of action potentials slowed; very prolonged PQ interval and loss of QRS complex from time to time |
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Term
| symptom of Type I second degree heart block |
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Definition
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Term
| type II second degree heart block |
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Definition
| conduction of action potential is slowed/blocked; very prolonged PQ interval and multiple P waves without QRS complex |
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Term
| symptom of Type II second degree heart block |
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Definition
| slow HR and could need artificial pacemaker |
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Term
| common reason for artificial pacemaker |
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Definition
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Term
| reason for third degree heart block |
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Definition
| heart disease or congenital in nature |
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Term
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Definition
| complete block of action potential conduction; very slow heart rate which leads to inadequate circulation |
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Term
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Definition
| block of action potential in atria; AV node activated sporadically |
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Term
| EKG of atrial fibrillation |
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Definition
| no observable P waves and no constant QRS spacing |
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Term
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Definition
| conduction system is disordered |
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Term
| EKG of ventricular fibrillation |
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Definition
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Term
| symptom of ventricular fibrillation |
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Definition
| loss of consciousness; death imminent if not remedied |
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Term
| right axis deviation (+90° to +180°) |
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Definition
| hypertrophy of the right side of the heart or damage to left side of the heart |
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Term
| right axis deviation could be due to |
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Definition
1) pulmonary hypertension
2) pulmonary valve dysfunction
3) heart attack that damages left side |
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Term
| left axis deviation (-30° to -90°) |
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Definition
| hypertrophy of the left side of the heart or damage to right side of the heart |
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Term
| left axis deviation could be due to |
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Definition
1) systemic hypertension
2) aortic valve dysfunction
3) heart attack that damages right side
4) athletic heart |
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Term
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Definition
| closing of valves and the collision of blood against them when they do close |
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Term
| opening and closing of valves is dictated by |
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Definition
| pressure changes in the chambers of the heart |
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Term
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Definition
| allow flow of blood through the heart in only one direction |
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Term
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Definition
| atrial pressure exceeds ventricular pressure |
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Term
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Definition
| ventricular pressure exceeds atrial pressure |
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Term
| semilunar valves open when |
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Definition
| ventricular pressure exceeds pulmonary trunk and aortic pressure |
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Term
| semilunar valves close when |
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Definition
| pulmonary trunk and aortic pressures exceed ventricular pressure |
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Term
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Definition
| closing of AV valves (tricuspid and mitral); longest and loudest sound |
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Term
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Definition
| closing of pulmonary and aortic semilunar valves |
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Term
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Definition
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Term
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Definition
| narrowing of valves which creates resistance to flow |
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Term
| stenosis murmur heard when |
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Definition
blood flows through the valve
AV stenosis prior to S1
semilunar stenosis prior to S2 |
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Term
| valve insufficiency/regurgitation |
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Definition
| improper closing of valves which causes back flow of blood through valve |
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Term
| valve insufficiency/regurgitation murmur heard when |
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Definition
valves close
AV insufficiency during S1
semilunar insufficiency during S2 |
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Term
| most commonly heard murmur |
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Definition
| mitral valve insufficiency |
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Term
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Definition
| blood flow to be turbulent |
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Term
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Definition
| events that make up one heart beat |
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Term
| average typical duration of cardiac cycle |
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Definition
| varies from .75 seconds to 1 second |
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Term
| duration of cardiac cycle dictates |
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Definition
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Term
| heart spends ___ of its time in systole |
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Definition
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Term
| heart spends ___ of its time in diastole |
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Definition
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Term
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Definition
| time atria are contracting |
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Term
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Definition
| time the ventricles are contracting |
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Term
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Definition
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Term
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Definition
| time ventricles are relaxing |
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Term
| 5 periods of cardiac cycle |
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Definition
1) isovolumic contraction (systole)
2) period of ejection (systole)
3) isovolumic relaxation (diastole)
4)passive ventricular filling(diastole)
5)active ventricular filling (diastole) |
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Term
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Definition
| volume of blood ejected to each great artery (~70mL) |
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Term
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Definition
| volume of blood in ventricles prior to ejection of blood (~120mL) |
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Term
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Definition
| percentage of blood ejected from each ventricle (55% to 70% is normal) |
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Term
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Definition
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Term
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Definition
| volume of blood in the ventricles after the stroke volume is ejected |
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Term
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Definition
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Term
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Definition
| relaxation of ventricles; ventricular pressure decreases below pressure of great arteries |
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Term
| passive ventricular filling |
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Definition
| ventricular pressure decreases further and is now lower than atrial pressure |
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Term
| active ventricular filling |
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Definition
| atria contract and actively fill ventricles with more blood |
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Term
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Definition
| ventricles begin to contract; ventricular pressure increases and eventually exceeds atrial pressure |
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Term
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Definition
| ventricular pressure increases further and exceeds pressure of great arteries |
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Term
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Definition
| volume of blood pumped by either the left or right ventricle in a minute |
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Term
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Definition
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Term
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Definition
| something that affects heart contractility and therefore stroke volume |
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Term
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Definition
| something that affects heart rate |
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Term
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Definition
| volume of blood in the ventricle immediate prior to systole (EDV) |
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Term
| Starling's law of the heart is a relationship between |
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Definition
| preload and heart contractility |
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Term
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Definition
| resistance the ventricle is exposed to when pumping |
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Term
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Definition
1) autonomic nervous system
2) hormones
3) body temperature |
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Term
| vagus nerve (PS) [description] |
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Definition
| primary controller of resting heart rate |
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Term
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Definition
| SA node, AV node, atrial myocardium |
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Term
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Definition
| inhibitory: decreases heart rate (negative chronotropic effect) |
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Term
| cardiac nerve (S) [description] |
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Definition
| primary controller of heart contractility |
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Term
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Definition
| SA node, AV node, atrial and ventricular myocardium |
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Term
| influence of cardiac nerve |
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Definition
| excitatory: increases heart rate (positive chronotropic effect) and increases heart contractility (positive inotropic effect) |
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Term
| function of epinephrine and norepinephrine |
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Definition
| bind to B-adrenergic receptors |
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Term
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Definition
| increase the number of B-adrenergic receptors |
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Term
| body temperature effect on heart rate |
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Definition
| change of 1°C changes heart rate approx. 10 beats per minute |
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