Regarding the mechanism of action of hormones indicate the FALSE statement:

Correct Answer: D

Rationale: The correct answer is D because many hormones actually exert their effects by interacting with specific receptors on the cell membrane rather than acting directly on subcellular membranes. This interaction triggers a series of intracellular events that lead to a cellular response. Option A is true as hormones indeed interact with specific receptors on cell walls. Option B is true as cyclic AMP is a common second messenger system utilized by hormones. Option C is true as many hormones stimulate adenylcyclase enzyme as part of their signaling pathway.

Correct Answer: B

Rationale: The correct answer is B: FALSE. COX-1 is constitutively expressed and involved in homeostatic functions, while COX-2 is inducible during inflammation to facilitate the inflammatory response. COX-1 is responsible for maintaining normal physiological functions, such as protecting the stomach lining and regulating blood flow, while COX-2 is primarily involved in producing prostaglandins during inflammation. Therefore, COX-1 is not induced during inflammation, and COX-2 is not homeostatic. Choice A is incorrect because COX-1, not COX-2, is homeostatic. Choice C is incorrect because there is a clear distinction between the functions of COX-1 and COX-2. Choice D is incorrect because not all options are correct; only option B is accurate based on the roles of COX-1 and COX-2 in the body.

Correct Answer: C

Rationale: The correct answer is C: GI disturbance. Cyclosporine A is known to cause gastrointestinal (GI) disturbances as a common side effect, including nausea, vomiting, abdominal pain, and diarrhea. This is due to its impact on the digestive system. Choice A (Diarrhea) is too specific and not the most common side effect. Choice B (Headache) is not a typical side effect of cyclosporine A. Choice D (Immunosuppression) is the intended therapeutic effect of cyclosporine A, not a side effect. Therefore, C is the correct choice based on the common side effects associated with cyclosporine A.

Correct Answer: D

Rationale: Step-by-step rationale for why D (Pellagra) is correct: 1. Dermatitis: Pellagra is characterized by skin rashes due to niacin deficiency. 2. Diarrhoea: Niacin deficiency in Pellagra affects the digestive system, leading to diarrhea. 3. Dementia: Niacin deficiency affects the brain, causing neurological symptoms like dementia. Summary of why other choices are incorrect: A: Dry beriberi is caused by thiamine (B1) deficiency, not niacin. B: Pyridoxine deficiency (vitamin B6) does not typically present with dermatitis, diarrhea, or dementia. C: Scurvy is caused by vitamin C deficiency and is characterized by bleeding gums, weakness, and fatigue, not the symptoms mentioned in the question.

Correct Answer: C

Rationale: The correct answer is C. Gemfibrozil (Lopid) has not been shown to reduce mortality associated with heart disease. This statement is false as fibric acid derivatives, including gemfibrozil, primarily work by lowering triglycerides and increasing HDL cholesterol levels, which may help in reducing the risk of heart disease but not mortality directly. Choices A, B, and D are all true statements about fibric acid derivatives. A: Clofibrate is indeed used for Type III hyperlipidemia. B: Gemfibrozil increases HDL cholesterol and lowers LDL cholesterol. D: Gemfibrozil is generally well tolerated with common side effects being gastrointestinal upset and myopathy.