Physio Pre-lab Quiz

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  1. normal heart rate of an adult with a healthy heart:
    72 bpm
  2. Excitatory and Electrical conduction systems of the heart is responsible for:
    contraction and relaxation of heart muscles
  3. SA node:
    • pacemaker
    • electricle impulse is generated
    • located: along posterior wall of right atrium; beneath opening of superior vena cava
    • crescent shaped
    • impulse from SA node -> AV node
  4. AV node:
    • responsible for conduction of the impulse from atria -> ventricles
    • impulse delayed slightly to allow complete emptying of atria before ventricles contract
    • impulse -> AV bundles -> bundles of Purkinje fibers
  5. Purkinje Fibers:
    conduct the impulse to all parts of the ventricles; causing contraction
  6. Vagal Stimulation:
    • parasympathetic
    • decrease in rate at SA node
    • decrease excitability of AV junction fibers
    • slows heart rate
    • severe cases: blockage of impulse through AV junction
  7. Sympathetic Stimulation:
    • increase rate at SA node
    • increase rate of conduction and excitability
    • increases force of myocardial contraction
    • overall workload on heart is increased
  8. Ectopic Foci:
    • small areas of heart become more excitable and cause abnormal heart beats
    • extra or skipped heartbeats
    • caused by ischemia, stimulants (nicotine/ caffine), lack of sleep
  9. Aberrant Conduction:
    • cause arrhythmias by providing a block or alternate route for the wave of depolarization
    • form short circuit bridge across the nonconductive tissue; tissue can depolarize prematurely or out of sync
    • conduction within the AV node or bundle of His can be blocked; AV nodal blocks
  10. Channelopathy:
    • inherited or aquired
    • predipose individual to dangerous arrhythmias
    • faulty ion channels result in prolonged repolarization; lengthening QT interval
    • heart is most vulnerable during repolarization
    • can be due to leaky or slow closing Na+ channels, ineffective K+ channels (inherited) or drugs and toxins which can affect the transport of ions across channels (aquired)
  11. EKG paper:
    • time: horizontal axis; small square = 0.04 sec; large square = 0.2 sec
    • voltage: vertical axis; 10mm = 1mV
    • heart rate can be easily estimated from EKG strip
    • count R waves in 6 sec strip; multiply by 10 = heart rate
  12. P wave:
    • atrial depolarization (followed by atria contraction)
    • normal duration: not longer than 0.11 sec (less 3 small squares)
    • height: no more than 3 mm
    • no notching or peaking
  13. QRS complex:
    • ventricular depolarization (followed by ventricles contraction)
    • normal duration: not longer than .10 sec
    • height: not less than 5 mm
    • R = positively deflected; Q and S = negatively deflected
  14. T wave:
    • ventricular repolarization
    • height: not more than 5 mm
    • rounded and asymmetrical
  15. ST segment:
    • early ventricular repolarization
    • Depressed: no more than 0.5 mm
    • may be elevated: no more than 1 mm
  16. PR interval:
    • AV conduction time
    • normal duration: 0.12 to 0.20 sec
  17. QT interval:
    • ventricular depolarization and repolarization
    • varies with rate
    • Prolonged QT may be inherited or aquired
    • inherited: defective Na+ or K+ channels
    • aquired: drugs (at least 50 drugs are know to affect QT; quinidine), electrolyte imbalance, or MI
Card Set
Physio Pre-lab Quiz
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