Pathophysiology Practice Exam

Correct Answer: B

Rationale: Acetylcholine acts as an inhibitory neurotransmitter at the sinoatrial node. It slows down the heart rate by decreasing the firing rate of the sinoatrial node, which serves as the heart's natural pacemaker. Neurotransmitters do not have a charge, so choice A is incorrect. Choice C is wrong as overstimulation is not a characteristic of acetylcholine at the sinoatrial node. Choice D is also incorrect because acetylcholine actively influences heart rate regulation when released at the sinoatrial node.

Correct Answer: A

Rationale: The correct answer is A. Botulism in infants is often linked to honey consumption. Asking the parents if they have ever given their child any honey or honey-containing products can provide crucial information for the differential diagnosis. This is important because infant botulism is commonly associated with the ingestion of honey contaminated with Clostridium botulinum spores. Choices B, C, and D are less relevant to botulism in infants as they do not directly relate to the typical causes of the condition. Family history of neuromuscular diseases (choice B) may be important for other conditions but not specifically for infant botulism. Direct exposure to chemical cleaning products (choice C) and the presence of mold in the home (choice D) are not typical risk factors for infant botulism.

Correct Answer: A

Rationale: Antibodies are produced by B cells. B cells are specialized white blood cells that generate antibodies as part of the immune response. B cells differentiate into plasma cells that secrete antibodies. T cells play a role in cell-mediated immunity, not antibody production. Helper cells, or helper T cells, assist in activating B cells but do not directly produce antibodies. Memory cells store information about previous infections but do not actively produce antibodies.

Correct Answer: C

Rationale: The correct answer is C. Oral contraceptives can be less effective when taken with certain antibiotics due to potential drug interactions that may reduce contraceptive efficacy. It is crucial for patients to be aware of this to consider additional contraceptive measures when prescribed antibiotics. Choice A is incorrect because while oral contraceptives are highly effective when taken correctly, they are not 100% foolproof. Choice B is incorrect as oral contraceptives may take some time to reach their full effectiveness after starting. Choice D is also incorrect as taking oral contraceptives with food does not significantly affect their efficacy.

Correct Answer: A

Rationale: The correct answer is A. Finasteride has been shown to lower the risk of developing prostate cancer. Studies have demonstrated that finasteride can reduce the incidence of prostate cancer. However, it is still recommended to have regular screening to monitor for any potential issues. Choice B is incorrect as finasteride has shown to have a positive effect on reducing prostate cancer risk. Choice C is inaccurate because finasteride decreases, not increases, the risk of prostate cancer. Choice D is incorrect as regular screening is still necessary despite the risk reduction associated with finasteride.