PCCN Cardiac Questions with Verified Answers

Which cation activates the second (slow-channel) inward flow of ions during cardiac depolarization? A. Sodium B. Potassium C. Chloride D. Calcium D. Calcium The sodium-potassium pumps are associated with rapid channel movement, so A and B can be eliminated initially. Chloride is an anion, so eliminate C as well. Calcium is the "slow channel" cation of phase 2 (the plateau phase). It is by working on this phase that calcium chloride IVP administration can increase contractility and protect the myocardium. Choose D. Which ion leaves the cell during depolarization to counter the inward flow of sodium? A. Phosphate B. Potassium C. Chloride D. Calcium B. Potassium The cell membrane will always favor exchanging a "positive for a positive" or a "negative for a negative." Since sodium is positive and phosphate (option A) and chloride (Option C) are negative, they can be eliminated quickly. The "sodium-potassium pump" suggests that sodium largely exchanges with potassium, making option B the best answer. Calcium is more associated with the slow-channel phase 2, so eliminate D. Which of the following cardiac chambers contains deoxygenated blood? A. Right ventricle B. Left ventricle C. Pulmonary veins D. Left atrium A. Right ventricle Left-sided cardiac chambers carry oxygenated blood, so options B and D can be eliminated quickly. The only right-sided chamber mentioned here is A, making option A the best answer. Even though the word "veins" is mentioned in option C, the pulmonary veins carry oxygenated blood to the right atrium from the lungs, thus eliminating option C as well. Where is the sinoatrial (SA) node located? A. Right atrium B. Left atrium C. Right ventricle D. Superior vena cava A. Right atrium The conduction pathway begins in the right atrium, travels through the bundle of His in the septum, then the apex of the LV and throughout the His-Purkinje system. The conduction impulse also begins with the sinoatrial (SA) node, so choose A. The superior vena cava, option D, is not even a cardiac chamber and can be eliminated quickly. Options B and C refer to either the incorrect side or the cardiac chamber in order to confuse the reader. Which component of blood pressure regulation has the strongest effect on controlling the blood pressure? A. Stroke volume B. Cardiac output C. SVR D. Mean arterial pressure C. SVR Cardiac output and stroke volume relate more to blood flow than blood pressure, so option A and B can be eliminated quickly. Mean arterial pressure is just another way to measure blood pressure, so D can be eliminated as well. Consider the formula MAP = CO x SVR. SVR measures the degree of afterload that compensates for changes in cardiac output (CO). SVR is also one of the primary parameters targeted for treatment of primary systemic HTN. Choose C.