A burn patient receives a skin graft; immunosuppressants prevent rejection. Which mechanism limits collagen synthesis, delaying wound healing, despite the graft?

💡 Explanation

Collagen synthesis requires hydroxylation of proline residues via prolyl hydroxylase; impaired activity limits stable triple helix formation. Immunosuppressants can inhibit this enzyme. Therefore, reduced prolyl hydroxylase limits collagen production, rather than growth factor signaling or TGF-beta.

• During a stress test, why does diastolic blood pressure sometimes decrease even when cardiac output and heart rate increase?
• A patient with a genetic mutation has impaired production of Vitamin K-dependent clotting factors. Which outcome becomes likely following a minor injury?
• What causes ascites in liver cirrhosis, specifically relating to the fibrotic tissue's impact on sinusoidal pressure?
• A subject undergoes sleep deprivation followed by recovery sleep. Why does REM sleep duration typically increase during recovery, particularly in the latter half of the sleep period?
• Why does isometric muscle contraction, while holding a heavy object stationary, still lead to muscle fatigue?
• An individual with opioid use disorder requires increasingly larger doses to achieve the same analgesic effect. Which mechanism explains why opioid tolerance develops within the reward circuitry?