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EKG CH 2
Chapter 2 notes
Question | Answer |
---|---|
Define Electrocardiogram | a recording of your heart's electrical activity printed onto graph paper so it can be easily measured. |
What are the two types of Cardiac Cells? | Myocardial and Pacemaker |
Define Myocardial cells | muscle cells, or "the working cells", the Myocardium has channels that allow certain electrolytes in or out of the cell. These electrolytes are sodium, potassium, calcium, magnesium, and chloride. |
Define Pacemaker cells | a specialized nerve cell that can create or conduct electrical impulses. These cells form the heart's conduction system. This electrical activity allows the heart muscle to contract. |
What are the 4 cardiac cell properties? | Automaticity, Conductivity, Excitability, Contractility |
Define Automaticity | a pacemaker cell's ability to create an electrical impulse. |
Define Conductivity | the ability of a cardiac cell to receive an electrical impulse and conduct it to an adjoining cardiac cell. |
Define Excitability | (irritability) the ability of cardiac muscle cells to respond to a stimulus. |
Define Contractility | the ability of cardiac muscle cells to shorten (contract) in response to an electrical stimulus. |
Define Polarization | a cardiac cell in the resting phase.; or when the inside of the cell is more negatively charged than the outside. |
Define Depolarization | differently charged electrolytes suddenly rush into and out of the cells, causing the inside of the cells to change from negative to positive. This creates electricity which spreads throughout the heart and causes a contraction of the heart. |
Define Repolarization | charged electrolytes rush back to resting phase which changes the inside of the cell back to negative. The process starts all over again |
Define Refractory Period | when a cell has depolarized, it must recover (repolarize) in order to respond to a new stimulus. |
Define Absolute Refractory Period | (1st part of repolarization) electrolytes are still so disorganized that they cannot respond to any new stimulus. |
Define Relative Refractory Period | (2nd part of repolarization) electrolytes of some cells have returned to a state in which a stronger-than-normal stimulus might cause depolarization. |
Where is the conduction system? | Embedded in the Endocardium |
Define Sinoatrial Node (SA Node) | a lump of pacemaker cells at the top of the right atrium that is your normal pacemaker site. It creates a wave of depolarization that spreads throughout the atria. |
Define Atrioventricular Node (AV Node) | normal impulses initiated by the sinus node spread throughout the atria and make their way down to the AV node at the bottom of the right atrium. The AV node slows the contraction and allows the ventricles to fill. |
Define Bundle of His | connects the Av node to the right and left bundle branches. It is located inside the superior portion of the inter ventricular septum. |
Define Right Bundle Branch | Delivers electricity from the Bundle of His to the right ventricle |
Define Anterior Left Bundle Branch | Delivers electricity from the Bundle of His to the front of the left ventricle |
Define Posterior Left Bundle Branch | Delivers electricity from the Bundle of His to the back of the left ventricle |
Define Purkinje Fibers | Numerous small branches that spread out over the epicardial surface of both ventricles. These help to deliver electricity quickly |
What does the EKG record? | The electrical activity related to depolarization and repolarization patterns throughout the heart |
What are the different modalities of the EKG? | Bedside monitoring (3-5 electrodes), 12 lead EKG (10 electrodes)(12 views of the heart), Holter monitoring (5-7 electrodes) (24hr EKG), Event monitoring (same as holter but only records symptomatic episodes), Cardiac Stress Testing (treadmill with 12 lea |
Define Bipolar lead | EKG leads that have a positive and negative electrode |
Define Unipolar lead | use one positive electrode and a mathematically determined negative reference point |
What lead color is the Right Arm | (RA) White |