What is the major effect of calcium channel blockers on cardiac contractions
Increases the rate of cardiac contractions
Decreases the strength of cardiac contractions
Stabilizes the rhythm of cardiac contractions
Stabilizes the vasodilation during cardiac contractions
The Correct Answer is B
Calcium channel blockers (CCBs) are a class of medications that block the influx of calcium ions into cardiac and smooth muscle cells, leading to relaxation of these muscles and dilation of blood vessels.
In the heart, CCBs primarily affect the L-type calcium channels in the cardiac myocytes, which are responsible for the influx of calcium ions during the plateau phase of the cardiac action potential. By blocking these channels, CCBs decrease the amount of calcium that enters the cardiac myocytes, which in turn reduces the strength of cardiac contractions (i.e. contractility). 
This reduction in contractility can be beneficial in certain conditions where the heart is working too hard or experiencing insufficient blood flow, such as in hypertension, angina, or some forms of arrhythmia. By reducing the workload of the heart, CCBs can help to lower blood pressure, decrease oxygen demand, and improve blood flow to the heart.
While CCBs can also have effects on the rate and rhythm of cardiac contractions, these effects are generally less pronounced than the reduction in contractility. Some CCBs, such as verapamil and diltiazem, can slow the heart rate by blocking the L-type calcium channels in the sinoatrial (SA) and atrioventricular (AV) nodes, while others, such as nifedipine, have little effect on heart rate.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
associated with chronic heart failure. Activation of the RAAS system occurs as a compensatory mechanism in response to decreased cardiac output and reduced renal perfusion. The renin-angiotensin-aldosterone system increases blood pressure, maintains blood volume and improves cardiac contractility in the short term, but in the long term it can lead to fluid retention, edema, and worsen cardiac function.
Correct Answer is C
Explanation
At high altitudes, the air pressure is decreased, and there is less oxygen available in each breath. This leads to a decreased partial pressure of oxygen in the lungs, which can cause hypoxemia (low oxygen levels in the blood). Hyperventilation may initially help to increase oxygen delivery to the body, but it can also lead to respiratory alkalosis and decrease oxygen delivery to the tissues in the long run.
Whether you are a student looking to ace your exams or a practicing nurse seeking to enhance your expertise , our nursing education contents will empower you with the confidence and competence to make a difference in the lives of patients and become a respected leader in the healthcare field.
Visit Naxlex, invest in your future and unlock endless possibilities with our unparalleled nursing education contents today