Which mechanism best explains how smoking delays wound healing?

Which mechanism best explains how smoking delays wound healing?

• A. Vasodilation increases tissue oxygen delivery
• B. Increases collagen synthesis
• C. Enhances immune function
• D. Vasoconstriction reduces tissue oxygen delivery

Answer: (D)

Smoking delays wound healing mainly because nicotine causes vasoconstriction, which reduces blood flow to the wound and thus lowers tissue oxygen delivery. When blood vessels constrict, less oxygen and fewer nutrients reach the healing tissue, slowing essential processes like collagen production, fibroblast activity, and new blood vessel formation. Additionally, smoke contains carbon monoxide, which binds to hemoglobin and decreases the blood’s oxygen-carrying capacity, further limiting oxygen available at the wound site. The other ideas would, in contrast, improve or not affect healing (vasodilation would increase oxygen delivery, more collagen synthesis would aid repair, and better immune function would help fight infection).

Smoking delays wound healing mainly because nicotine causes vasoconstriction, which reduces blood flow to the wound and thus lowers tissue oxygen delivery. When blood vessels constrict, less oxygen and fewer nutrients reach the healing tissue, slowing essential processes like collagen production, fibroblast activity, and new blood vessel formation. Additionally, smoke contains carbon monoxide, which binds to hemoglobin and decreases the blood’s oxygen-carrying capacity, further limiting oxygen available at the wound site. The other ideas would, in contrast, improve or not affect healing (vasodilation would increase oxygen delivery, more collagen synthesis would aid repair, and better immune function would help fight infection).