Which of the following neural pathways most likely represent the main site of therapeutic action of the drug in the 8-year-old boy diagnosed with ADHD?

Correct Answer: B

Rationale: The correct answer is B: Mesolimbic pathway. In ADHD, dysfunction in the mesolimbic pathway, involved in reward and motivation, is often implicated. Stimulant medications like those used to treat ADHD act on this pathway to improve focus and impulse control. The other pathways listed do not play as significant of a role in ADHD symptomatology. A: Tuberoinfundibular is involved in hormonal regulation, not ADHD. C: Corticostriatal is more associated with movement control. D: Mesocortical is related to cognitive functions, but not the main site of therapeutic action for ADHD.

Correct Answer: D

Rationale: The correct answer is D: Buprenorphine. Buprenorphine is commonly used to treat opioid addiction and dependence due to its partial agonist activity at the mu-opioid receptor, which helps reduce cravings and withdrawal symptoms. Methadone (A) is also used for opioid addiction treatment but is more commonly administered in specialized clinics. Meperidine (B) is primarily used for acute pain management and has a high potential for toxic metabolites. Codeine (C) is a weaker opioid commonly used for mild to moderate pain and cough suppression, not typically used for addiction treatment.

Correct Answer: D

Rationale: The correct answer is D because methadone stimulates adenylyl cyclase activity as a postreceptor mechanism. Methadone is an opioid receptor agonist that activates G-protein coupled receptors, leading to the activation of adenylyl cyclase and subsequent increase in cAMP levels. This increased cAMP signaling pathway results in various downstream effects, including modulation of neurotransmitter release and neuronal excitability. A: Inhibition of the synthesis of inositol triphosphate/diacylglycerol (IP3/DAG) is not a postreceptor mechanism triggered by methadone. B: Blockade of Ca2+ channels on presynaptic nerve terminals is not a postreceptor mechanism triggered by methadone. C: Opening of Na+ channels on neuronal cell membrane is not a postreceptor mechanism triggered by methadone. In summary, methadone's stimulation of adenylyl cyclase activity is the correct choice as it align

Correct Answer: B

Rationale: The correct answer is B: Morphine. Postoperative adynamic ileus is characterized by delayed gastric emptying and reduced intestinal motility. Morphine can exacerbate these symptoms by causing further gastrointestinal motility issues, leading to potential complications such as bowel obstruction. Acetaminophen (A), Ibuprofen (C), and Ketorolac (D) do not have significant effects on gastrointestinal motility and are therefore safer choices for patients with postoperative adynamic ileus.

Correct Answer: B

Rationale: The correct answer is B: Increased heart rate. When smoking, nicotine enters the bloodstream and stimulates the release of adrenaline, leading to increased heart rate. Hypertension (choice A) may occur over time with consistent smoking. Depressive mood (choice C) is more commonly associated with withdrawal symptoms rather than immediate effects. Hyperalgesia (choice D), increased sensitivity to pain, is not a typical immediate effect of smoking.