Modifiers that affect heart rate are _______.Question 20Select one:A.agonistsB.antagonistsC.inotropicD.chronotropic

Analyzing the Question

The question is asking about modifiers that specifically affect heart rate. Let's analyze the provided options to determine the correct answer.

Understanding the Options

1. A. Agonists - These are substances that activate receptors to produce a biological response. They can affect heart rate but are not specifically modifiers of heart rate itself.

2. B. Antagonists - These substances block receptors and prevent a biological response. Like agonists, they influence heart function but don’t specifically modify heart rate classification.

3. C. Inotropic - This term refers to the force of contraction of the heart muscle. Inotropic agents affect the strength of heart contractions rather than directly modifying the heart rate.

4. D. Chronotropic - This term specifically refers to factors that influence the heart rate, either increasing or decreasing it.

Conclusion

Given the definitions and functions of each term, the most suitable answer is D. Chronotropic, as it directly relates to modifications of heart rate.

Final Answer

D. Chronotropic