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Lab Exercise 4
| Question | Answer |
|---|---|
| Intrinsic Stimulation | caused by specialized, noncontractile cells called autorhythmic cells |
| Intrinsic Conduction System | initiates action potentials for cardiac muscle fiber contraction and provides a pathway for conducting the action potential to all cardiac muscle fibers |
| Extrinsic Stimulation | ANS and hormones, only increase or decrease the intrinsic pace |
| Electrocardiograph | records electrical changes in the heart |
| Electrocardiogram (ECG or EKG) | chart recording of the electrical events before each heartbeat |
| P Wave | atrial depolarization, just before atrial contraction |
| QRS Complex | ventricular depolarization, before ventricles contract. Occurs during atrial repolarization |
| T Wave | ventricular repolarization, before ventricles contract |
| P-Q Interval | the time interval between the beginning of contraction of the atrium and the beginning of the contraction of the ventricle |
| Q-T Interval | the time from beginning of ventricular depolarization until the end of ventricular repolarization - ventricles are contracting |
| S-T Segment | represents the time the ventricular fibers are fully depolarized |
| Normal Sinus Rhythm | normal heart rate of 60-100 beats/min |
| Tachycardia | HR >100 beats/min |
| Bradycardia | HR <60 beats/min |
| Fibrillation | from prolonged tachycardia, rapid uncoordinated heart contractions that do not pump blood |
| Complete Heart Block | ventricles depolarizing independently from the atria |
| Heart Block | produced by cardiac damage to the AV node or bundle, reducing electrical conduction from atria to ventricles, P-Q interval >0.2 seconds |
| Right or Left Bundle Block | two ventricles do not contract simulatneously and QRS is prolonged. |
| Myocardial Ischemia | decreased blood flow, longer Q-T interval |
| Myocardial Damage | lengthens Q-T interval |
| Mean Electrical Axis (MEA) | average direction of depolarization as the impulses spread into the ventricles. |
| Hypertrophy | of one ventricle shifts the MEA toward the hypertrophied ventricle, because it takes longer to depolarize, about +59 degrees |
| Mean Electrical Magnitude | average voltage of depolarization |
| T/F: EKGs give info about the force of contraction of the cardiac muscle | False |
| Aside from the ANS, what other factor causes extrinsic stimulation | hormones |
| Cardiac Cycle | time in seconds for one heartbeat |
Created by:
connorquinby
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