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Ch 26 - Cardio
Nursing
Question | Answer |
---|---|
The three layers of the heart? | Endocardium, myocardium, epicardium. |
What compses the two layers of the pericardium and how much fluid can be located? | The visceral pericardium & parietal pericardium. There is 30mL of fluid. |
What is the only artery in the body that does not contain oxygenated blood? | Left pulmonary artery. |
What are the thin fibrous bands that close the leaflet valves? | Chordae Tendineae. |
When does the coronary arteries receive blood from the heart? | The coronary arteries receive blood during diastole of the heart from. |
How much of the oxygen from the lung is used by the heart? | 70 - 80% |
Why can an increase in heart rate cause a myocardial ischemia? | An increase in heart rate shorten diastole and can decrease myocardial perfusion. |
What is the coronary sinus? | There area where the majority of venous blood of the heart is returned. |
The myocardium is composed of specialized cells called myocytes. What shape does this structure take and what is it purpose? | a figure eight pattern, which allows a twisting and compressive movement of the heart. |
What are the two specialized cells of the cardiac conduction system? | Nodal Cells and the Purkinje cells. |
What are the three characteristics of the nodal and purkinje cells that provide synchronization? | Automaticity, Excitability, Conductivity. |
The SA and AV nodes are both composed of what type of specialized cell? | Node cells |
What is the SA (sinoatrial node) firing rate of a normal resting adult? | 60 - 100 impulses per min. |
The electrical signal initiated byt he SA nodes are conducted though specialized tracts called? | Internodal pathways. |
Where can one locate the AV node? | In the right atrial wall near the tricuspid vale. |
What myocardial cell determine heart rate? | The one with the fastest inhert firing rate. |
Compare the impulses of the SA, AV nodes, and Ventricular pacemaker (bundle of hiss). | SA node 60-100 AV node 40-60 Ventricular pacemakes 30-40 |
Of the three ions that stimulate the cardiac working cells which moves the fastest and which moves the slowest? | Sodium is the fastest. Calcium is the slowest. |
What is the cardiac action potential? | The repeated cycles of depolarization and repolarization. |
What occurs to begin phase 0? | Cellular depolarization. |
How does calcium channel blockers (CCB) slow heart rate? | Both the SA and AV nodes are depolarized by the movement of Ca through the calcium channel. CCB slows this movement and thereby slows the conductive impulse. |
What characterize Phase 1? | Early cellular repolarization, as the K exits the intracellular space. |
What phase is called the plateau phase and what occurs during that phase? | Phase 2 is called the plateaus phase b/c the reate of repolarization slows. Ca ions enter the intracellular space. |
What happens in Phase 3? | Completion of repolarization. |
What happens in Phase 4? | The resting phase before the next depolarization. |
What drugs would you administer to suppress dysrhythmia formation and how do they function? | Class I antiarrhythmic, which block the influx of Na. The drugs are Lidocaine (Xylocaine), Quinidine (Quinalan), and propafenone (Rythmol). |
What class would you find Metoprolol (Lopressor), sotalol (Betapace)? What do they do and what condition would you give them? | The are class II (beta-blockers). They are given to help slow tachycardia by decreasing automaticity. |
What drug would you give to suppress atrial or ventricular dysrhythmias? How do they function? | Class III amiodarone (cordarone), which prolong repolariztion. |
What are Verapamil (Calan), diltiazem (Cardizemi) and what condition do you them to tx? | Class IV (CCB), used to treat tachycardia. |
What is the refractory period and what is it's importance? | It is a period where the cell is incapable of being stimulated, as it wait to be complete repolarized. |
What are the two phase of the refractory period? | Effective (absolute) refractory period and relative refractory period. |
During the relative refractory period the cell my depolarize prematurely if a stronger than normal electrical stimulus is given. What Cardiac action phases would this occur in and how would this effect the pt? | The relative refractory period can occur a short time after phase 3 and it increases the pt risk for dysrhythmias. |