CV System_ Heart Electrical Conductivity E&P2.pdf

Intrinsic Regulation of Heart Rate - Unlike other tissues, cardiac muscle maintains its own rhythm - Left to its inherent rhythmicity → would beat ~100 bpm - Sinoatrial (SA) node provides innate stimulus for heat action - “Heart’s pacemaker” = SA node Normal Route of Myocardial Impulse Transmission...

Intrinsic Regulation of Heart Rate - Unlike other tissues, cardiac muscle maintains its own rhythm - Left to its inherent rhythmicity → would beat ~100 bpm - Sinoatrial (SA) node provides innate stimulus for heat action - “Heart’s pacemaker” = SA node Normal Route of Myocardial Impulse Transmission - A little bit of an asynchronous contraction as the right side contracts a split second sooner compared to the left as a result of the nerve impulse transmission Electrocardiogram (ECG) - Myocardium’s electrical activity creates electrical field t/o the body - ECG represents a composite record of the heart’s electrical events during a cardiac cycle - These electrical events can monitor HR during physical activity and exercise stress testing - A valid ECG tracing requires proper electrode placement - ECG leads transmit electrical signal to a recorder, which creates the composite electrical “3D picture” of myocardial activity - Electrical signal looks diff. based on what view and angle you’re at, at diff. dimensions of space Normal Route of Myocardial Impulse Transmission - Cardiac conduction: repeating electrical impulses travel through heart to control heart muscle’s rhythmic contraction and dilation - 1. Impulse originates from sinoatrial (SA) node in the right atrium → spreads across the atria causing them to contract - 2. Impulse passes to the atrioventricular node (AV), travels along the atrioventricular bundle into its’ 2 branches, the right and left crus, and spreads into the ventricles causing them to contract - 3. Dissipation of the impulse causes the atria and ventricles to relax or dilate - 1. Sinoatrial node (SA) 2. Interatrial septum 3. Atrioventricular nodal (AV) 4. Atrioventricular bundle (bundle of His) 5. Right crus 6. Left crus 7. Interventricular septum (stiffens) 8. Purkine’s fibers ECG Waves - P wave: depolarization of atria before atria contract - QRS complex: signals electrical changes from ventricular depolarization before ventricles contract - Atrial repolarization after P wave but makes wave so small that QRS complex obscures it - T-wave: represents ventricular repolarization that occurs during ventricular diastole Electrocardiogram (ECG) and HR - Typically measuring an R to R → typically irregular = decent recover - Greater HRV → better indication of allowing system to relax and recover Normal ECG Phases - Ventricles DO NOT contract on p wave but it does facilitate (help) that occur Electrocardiogram (ECG) and Pathology Detection - Large low spaces → heart not told to contract which can be an issue (ex. heart block)