An 18 year-old college freshman presents to the emergency room for evaluation of fever, headache, and neck stiffness. On physical examination, the patient is resting quietly and has a flushed face. His vital signs are as follows: temperature, 104 F; pulse, 110 bpm; and BP, 105/70. He has no rashes. During the physical examination, you flex the patient's neck and his hips and knees flex in response, indicating a meningeal irritation. The name of this positive sign is:

Correct Answer: B

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.

Correct Answer: C

Rationale: Cadherins are cell adhesion molecules that mediate short-range contact attraction, guiding axons to their targets. Netrins, semaphorins, and ephrins also play roles in axon guidance, but they function through different mechanisms, such as long-range chemotaxis or repulsion. This diversity of guidance cues ensures precise navigation of growing axons.

Correct Answer: C

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.

Correct Answer: A

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.

Correct Answer: C

Rationale: Acetylcholine is the neurotransmitter responsible for mediating parasympathetic (rest-and-digest) functions, which resume control after a sympathetic (fight-or-flight) response. Norepinephrine mediates the sympathetic response, while serotonin and prostaglandins are involved in mood and pain regulation. Understanding neurotransmitter roles is key to explaining autonomic nervous system function.