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 D
Explanation
Hemoptysis is the coughing up of blood or bloody secretions from the respiratory tract. It is a sign of a serious condition and should be reported immediately to a healthcare provider. In this case, the patient's cold and cough may have led to irritation and inflammation of the respiratory tract, resulting in hemoptysis.
- Hematemesis: This is the vomiting of blood from the upper gastrointestinal tract, which usually appears bright red or dark brown in color.
- Cyanosis: This is a bluish discoloration of the skin and mucous membranes caused by the presence of deoxygenated hemoglobin in the blood.
- Rhinitis: This is the inflammation of the nasal mucosa, often causing a runny nose, nasal congestion, and sneezing.
Correct Answer is D
Explanation
Tachycardia refers to a heart rate that is faster than the normal range, which is typically considered to be between 60 and 100 beats per minute in adults. A heart rate of 110 beats per minute is above the normal range and is considered tachycardia.
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