Correct Answer: D

Rationale: The autonomic nervous system controls involuntary bodily functions like heart rate, respiration, and sweating. In the given scenario, the 'fight or flight' response is activated, leading to increased heart rate, palpitations, anxiety, and shaky hands. The cerebral cortex is involved in conscious thought processes and decision-making, not the immediate physiological response observed here. The somatic nervous system regulates voluntary movements, while the limbic system is responsible for emotions and memory, but the autonomic nervous system is primarily responsible for the physiological responses seen in this situation.

Correct Answer: A

Rationale: The correct answer is Avanafil (Stendra). Avanafil has a rapid onset of action compared to other PDE5 inhibitors, making it suitable for patients experiencing delays in onset and peak of action with other medications like Viagra. Tadalafil (Cialis), Vardenafil (Levitra), and Alprostadil (Caverject) do not offer the same rapid onset of action as Avanafil, making them less suitable for addressing the specific needs of this patient.

Correct Answer: C

Rationale: The correct answer is C: Ischemia. In this scenario, the 75-year-old male experiences chest pain on exertion, which is indicative of angina. Angina is primarily caused by reduced blood flow to the heart muscle, leading to hypoxic injury. This condition is known as ischemia. Options A, B, and D are incorrect. Malnutrition does not typically cause chest pain related to exertion. Free radicals and chemical toxicity are not common causes of chest pain in the context described. Therefore, the most likely cause of chest pain in this case is ischemia due to reduced blood flow.

Correct Answer: A

Rationale: The correct answer is A. Chronic pain is often complex and challenging to treat, necessitating a multimodal approach that may include medication, physical therapy, and behavioral therapy. Choice B is incorrect because chronic pain does not always indicate that an underlying injury has not healed properly; it can persist even after the initial injury has healed. Choice C is incorrect as chronic pain management usually involves a combination of treatments rather than relying solely on a single long-term medication. Choice D is incorrect because chronic pain is not necessarily less severe than acute pain; it can vary in intensity and duration depending on the individual and underlying condition.

Correct Answer: A

Rationale: Mifepristone (RU-486) functions by inhibiting the action of progesterone, a hormone crucial for maintaining pregnancy. By blocking progesterone, mifepristone disrupts the uterine environment necessary for pregnancy continuation, ultimately leading to termination. Choice B is incorrect because mifepristone does not increase estrogen levels; instead, it acts on progesterone. Choice C is incorrect as mifepristone's mechanism does not involve altering the uterine lining to prevent implantation. Choice D is incorrect because mifepristone does not directly stimulate uterine contractions; its primary action is through progesterone inhibition.