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 B
Explanation
The correct answer is B. Systolic pressure less than 120 mmHg and diastolic pressure less than 80 mmHg is considered normal blood pressure in adults according to current guidelines. A systolic pressure between 140-150 mmHg (option A) would be classified as stage 1 hypertension, while a systolic pressure greater than 140 mmHg and diastolic pressure of 100 mmHg (option D) would be classified as stage 2 hypertension. A systolic pressure less than 100 mmHg regardless of diastolic pressure (option C) would be considered low blood pressure.
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