A patient reports nearly having a motor vehicle crash and states that his heart was pounding and he was breathing heavy and fast. Currently, the patient's heart rate and breathing are within normal limits. Which neurotransmitter has resumed control after the patient's incident?

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.

Correct Answer: D

Rationale: Myasthenia gravis and botulism are conditions that result from impaired acetylcholine function. Myasthenia gravis is an autoimmune disorder that blocks acetylcholine receptors, while botulism prevents acetylcholine release. Multiple sclerosis affects the myelin sheath, not acetylcholine. Understanding these conditions highlights the importance of acetylcholine in neuromuscular communication.

Correct Answer: A

Rationale: The correct answer is A: preganglionic parasympathetic. Preganglionic fibers are the longest in the autonomic nervous system, with parasympathetic fibers generally having longer preganglionic fibers compared to sympathetic fibers. Parasympathetic preganglionic fibers originate from the cranial nerves and sacral spinal cord, allowing them to travel longer distances to reach their ganglia. In contrast, sympathetic preganglionic fibers originate from the thoracic and lumbar spinal cord, resulting in shorter lengths compared to parasympathetic fibers. Therefore, preganglionic parasympathetic fibers are considered the longest among the given choices. Postganglionic fibers, whether parasympathetic or sympathetic, are shorter as they only need to travel to their target organs from the ganglia. Summary: - A: Correct, as preganglionic parasympathetic fibers are the longest in the autonomic nervous system

Correct Answer: A

Rationale: Rationale for Correct Answer (A): 1. Nicotinic receptors are present in both sympathetic and parasympathetic divisions of the autonomic system. 2. Drugs affecting both divisions target nicotinic receptors to modulate autonomic functions. 3. Binding or blocking nicotinic receptors can impact both sympathetic and parasympathetic activities. Summary of Incorrect Choices: B. Muscarinic receptors are specific to the parasympathetic division, not affecting the sympathetic division. C. α-adrenergic receptors are specific to the sympathetic division, not influencing parasympathetic functions. D. β-adrenergic receptors are also specific to the sympathetic division, not impacting the parasympathetic division.

Correct Answer: C

Rationale: The correct answer is C: blowing nose. Leprosy is primarily transmitted through respiratory droplets when an infected person coughs or sneezes. This is because the bacteria that cause leprosy are mainly spread through respiratory secretions. The other choices (A: contaminated toilet seats, B: shaking hands, D: sexual intercourse) are not common modes of transmission for leprosy. Toilet seats do not play a significant role in transmission, shaking hands is unlikely to transmit the bacteria, and leprosy is not a sexually transmitted disease. Overall, the correct answer aligns with the known mode of transmission of leprosy through respiratory droplets.