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.
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Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is D
Explanation
Chronic bronchitis is a type of chronic obstructive pulmonary disease (COPD) that is characterized by inflammation and narrowing of the bronchial tubes, which can lead to symptoms such as cough, shortness of breath, and wheezing. The primary cause of chronic bronchitis is smoking, and the most effective way to halt its progression is by quitting smoking.
Smoking cessation is the cornerstone of treatment for chronic bronchitis, as continued smoking can worsen inflammation in the airways and accelerate the progression of the disease. In addition to smoking cessation, other treatments may include bronchodilators (such as albuterol) to help open the airways and improve breathing, postural chest drainage techniques to help clear mucus from the lungs, and antibiotics to treat bacterial infections.
While these treatments can help manage symptoms and prevent complications, they are not as effective as smoking cessation in halting the progression of chronic bronchitis. Therefore, it is important for individuals with chronic bronchitis to quit smoking as soon as possible to slow the disease process and improve their overall health.
Correct Answer is A
Explanation
Coronary artery disease (CAD) is a condition where the arteries that supply blood to the heart become narrowed or blocked due to a buildup of plaque. Several risk factors contribute to the development of CAD, including diabetes mellitus, hypertension, obesity, high alcohol consumption, smoking, and a family history of CAD.
Research suggests that individuals with diabetes mellitus are two to four times more likely to develop CAD than those without diabetes. This is because diabetes can lead to damage to the blood vessels and nerves that control the heart, as well as increased inflammation and high levels of blood glucose that can contribute to the buildup of plaque in the arteries.
While hypertension, obesity, and high alcohol consumption are also known risk factors for CAD, they generally do not increase the risk to the same degree as diabetes. Nonetheless, these factors can contribute to the development and progression of CAD and should be addressed through lifestyle modifications and medical interventions.
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