Lab 3 Student Notes

Lab 3 Student Notes - Lab 3 Conduction System of the Heart...

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Lab 3 Conduction System of the Heart and Electrocardiography (Exercise 31) A. The Intrinsic Conduction System 1. SA Node (sinoatrial node) pacemaker [sinus rhythm] 2. Internodal Pathways 3. AV Node (atrioventricular Node) slow - last portions of the atria to be depolarized - slowness due to: a) AV nodal fibers are very small b) fewer gap junctions c) more embryonic type of cells in fibers [junctional rhythm] 4. AV Bundle (Bundle of His) - right and left bundle branches 5. Purkinje Fibers fast Tachycardia = heart rate over 100 beats/min. Bradycardia = heart rate below 60 beats/min. flutter – low freq., coordinate contractions up to 200-300 beats/min. fibrillation – high freq., incoordinate contractions
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B. Electrocardiography Electrocardiogram (ECG or EKG) 1. P Wave (1 st ) - small upward wave - atrial depolarization 2. QRS Wave (complex) - Q is downward, R is large upward, S is large downward - ventricular depolarization 3. T Wave - ventricular repolarization enlarged P --- mitral stenosis (expansion of atrial wall) enlarged Q --- myocardial infarction enlarged R --- enlarged ventricles flat T --- insufficient oxygen as in atherosclerosis or elevated potassium ions (K + ) longer PR interval --- atherosclerotic heart disease, rheumatic fever, scared/inflamed atria to AV node elevated ST segment --- acute myocardial infarction
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This note was uploaded on 02/01/2011 for the course BIOL 228 taught by Professor Marilynkoob during the Fall '10 term at Boise State.

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Lab 3 Student Notes - Lab 3 Conduction System of the Heart...

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