A person with opioid addiction requires increasingly higher doses to achieve the same pain relief. What causes the decreased opioid effectiveness over time?

💡 Explanation

Tolerance develops to opioids because the body reduces the number of opioid receptors through receptor downregulation to maintain homeostasis in the dopamine reward circuit. Therefore, higher doses are needed to activate the remaining receptors, rather than the body producing more opioid peptides.

• Why does a person with damaged A-beta fibers touching rough sandpaper report diminished tactile acuity, relative to undamaged individuals?
• A patient with autoimmune hemolytic anemia experiences increased red blood cell destruction. Which mechanism explains why IgG autoantibodies cause this destruction?
• As humans age, why do arteries stiffen, increasing systolic blood pressure, despite dietary interventions?
• Why does adaptation to a sour taste diminish significantly faster when the tongue is excessively dry?
• If a patient exhibits severe muscle weakness and neurological dysfunction despite adequate protein intake, which cofactor-related deficiency is the MOST likely underlying cause?
• Why does a neuron's action potential propagate unidirectionally away from the soma, rather than bidirectionally?