N471 U3 Clinical Prevention Practice Exam Questions and Answers 100% Success/ A+ Score

N471 U3 Clinical Prevention Practice Exam Questions and Answers 100% Success/ A+ Score What do ECG's do? - ANS-detect abnormal transmission of cardiac impulses through the conductive tissue; diagnose specific abnormalities by evaluating electrical activity of the myocardium What will an ECG tell you? - ANS-1. Size of heart 2. Orientation of heart 3. Rhythm disturbances 4. Injury, ischemia, or infarct 5. Electrolyte abnormalities 6. Drug toxicity What are the parts of the myocardium conduction system and the rates of nodes? - ANS-- SA node: rate=60-100 bpm - Internodal fibers - AV node "Junction": rate=40-60 bpm - Bundle of His - Bundle branches -Perkinje fibers What does the bundle of His do? - ANS-conducts impulses to bundle branch system what do the bundle branches do? - ANS-conducts impulses through ventricles what do the perkinje fibers do? - ANS-conducts impulses into subendocardial layers; depolarize from endocardium to epicardium What does the T wave represent? - ANS-repolarization of ventricles What does the p wave represent? - ANS-atrial contraction (depolarization) If the T wave is the repolarizing of the ventricle, where is the repolarizing of the atria? - ANS-Lost in the QRS complex What do all heart cells have? - ANS-a membrane potential which is simply a difference in electrical charge across a semi-permeable membrane What are the two phases of potentials? - ANS-Resting membrane potential (RMP) or action potential What are the two stages of action potentials? - ANS-depolarization and repolarization What is automaticity? - ANS-the ability to spontaneously depolarize what is rhythmicity? - ANS-the ability to depolarize regularly What is refractoriness? - ANS-the state of a cell during repolarization when cells cannot depolarize regardless of the intensity of the stimulus or require a much greater stimulus than normal What is the Na+ concentration like? - ANS-greater outside the cell than inside what is the K+ concentration like? - ANS-greater inside the cell than outside What causes changes in resting membrane potential? - ANS-chemical, electrical, or mechanical stimulation What are the two types of cells in action potential? - ANS-Myocardial cell and pacemaker cell What is the process of action potential in a myocardial cell? - ANS-1. Stimulus hits the resting membrane 2. Influx of Na+ produces rapid depolarization 3. Initial repolarization as some K+ leaves the cell 4. Slow influx of Ca+ keeps inside positive (Ca entering the cell provides for release of intra-cardiac Ca stores and muscle contraction) 5. Repolarization phase; inactivation of slow Ca channel begins preventing further influx of Ca; K+ continues to leave the cell; leads to cell becoming more negative, leading to reestablishment of the RMP 6. Excess Na+ that entered the cell during depolarization is removed via the Na-K Pump; inside the cell returns to a negative state and outside a positive in preparation for the next stimulus which will lead to depolarization What is the process of action potential in pacemaker cells? - ANS-1. a slow influx of Na+ results in a gradual incline 2. depolarization and repolarization occur due to a steady influx of Na and efflux of K in these specialized cell membranes *they require NO outside stimulus to depolarize spontaneously. What do pacemaker cells provide? - ANS-the electrical stimulus for depolarization of the myocardial cells What are refractory periods and the various types? - ANS-where myocardial cells action potentials are resistant to a new stimulus Absolute refractory Relative refractory vulnerable period normal excitability What is absolute refractory period? - ANS-Phases 0, 1, and 2 where the myocardial cells cannot respond to another impulse because of total depolarization what is relative refractory? - ANS-Phase 3 during repolarization where the cell may respond to an impulse if the intensity of the impulse is above normal threshold What is the vulnerable period? - ANS-the end phase 3 to phase 4 where there is increased excitability during which a weaker than normal impulse can provoke repetitive depolarizations what is Normal excitability - ANS-phase 4 where there is no refractoriness present so excitability is normal Where is the P-wave on the ECG from? - ANS-the SA node which has automaticity that starts the AP of the myocardial cells around the SA node What does the SA node act as? - ANS-the pacemaker for the heart What does the T-wave of the ECG correspond closely to? - ANS-phase 3 of the myocardial cells action potential What are the two mechanisms of dysrhythmias? - ANS-abnormal automaticity and re-entry what is abnormal automaticity? - ANS-is present in pacemaker cells only and is the property of spontaneous depolarizations resulting from altered impulse formation What are the two alterations in nodal cells action potential? - ANS-- increase slope: leads to tachycardias and premature beats - decreased slope: leads to bradycardias and latent pacemakers Do myocardial cells possess automaticity? - ANS-NO; they need outside stimulus What is Re-entry and when does it occur? - ANS-is impaired conduction where there are branching pathways and a unidirectional block present occurs in ischemic conditions what can re-entry create? - ANS-an isolated ectopic beat or a series of fast, repetitive beats (tachycardias) What is a vector? - ANS-when many cardiac cells' membrane potentials change concurrently forming an electrical force that has both direction and magnitude. What is a vector recorded by and what does it record? - ANS-recorded by an electrode on the chest surface; records only electrical activity *When a vector is detected, the electrode records a deflection from baseline What does a vector traveling toward a positive electrode produce? - ANS-a positive deflection What does a vector traveling away from a positive electrode produce? - ANS-a negative deflection What are the 4 types of leads? - ANS-limb, augmented, chest, MCL1 How many limb leads are there, what do they measure, and what are they named - ANS-3; bipolar; frontal plane; named I, II, III How many augmented leads are there, what do they measure, and what are they named? - ANS-3; unipolar; increased amplitude of the deflections by 1.5x; named aVR, aVL, aVF How many chest leads are there, what do they measure, and what are they named - ANS-6; unipolar; horizontal plane; named V1-V6 What is the MCL1 lead? - ANS-modified chest lead 1:1; helps with early detection of dysrhythmias, bundle branch blocks, and ischemic changes What is a systematic review of an entire rhythm? - ANS-1. Regular or irregular rhythm 2. Rate: both atrial and ventricular 3. P wave (represents atrial contraction) 4. Determine PR interval 5. Determine QRS complex 6. Evaluate QT interval 7. Identify origin of the dysrhythmias if possible 8. Identify nurse action if there is any What questions do you ask when looking at P-wave? - ANS-- identify presence of p-wave - what is the P-waves relationship to QRS complex? - Is there a P wave for every QRS complex? - Do all P waves look the same? ........