Ellis curve is seen in –
**Core Concept**
Ellis curve is a graphical representation of the relationship between the concentration of a drug and its effect on the body. It is a sigmoid-shaped curve that illustrates the dose-response relationship of a drug, typically showing a gradual increase in effect as the dose increases, followed by a plateau and eventually a decrease in effect at higher doses.
**Why the Correct Answer is Right**
The Ellis curve is specifically seen in the context of the effect of a drug on the heart, where it describes the relationship between the concentration of a drug and its effect on the heart rate. This curve is typically observed in the context of the administration of a beta-blocker, such as propranolol, which decreases heart rate. The curve illustrates the gradual increase in heart rate decrease as the dose of the drug increases, followed by a plateau and eventually a decrease in effect at higher doses due to receptor desensitization.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the Ellis curve is not typically associated with the effect of a drug on blood pressure, which is more accurately described by a different type of dose-response curve.
**Option B:** This option is incorrect because the Ellis curve is not typically associated with the effect of a drug on the respiratory system, which is more accurately described by a different type of dose-response curve.
**Option C:** This option is incorrect because the Ellis curve is not typically associated with the effect of a drug on the central nervous system, which is more accurately described by a different type of dose-response curve.
**Clinical Pearl / High-Yield Fact**
The Ellis curve is a classic example of a sigmoid-shaped dose-response curve, which is a fundamental concept in pharmacology. Understanding the shape and characteristics of this curve is essential for predicting the effect of a drug and avoiding adverse effects.
**Correct Answer: D.**