system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do cigarettes make people visually age?
gpt
There are number of reasons cigarettes make people look older but a major reason is that smoking causes your blood vessels to constrict. That decreases the blood supply (and the nutrients the blood carries) to all of your organs, including the largest one: your skin. The proteins like collagen and elastin that regular give your skin and soft tissues structure are weakened or not synthesized in as high a number as a result. People develop crow's feet and wrinkles at an earlier age. Diminished blood supply also means that when these people are injured, their wounds are going to heal much more slowly. This is why a lot of surgeons won't operate on people that smoke unless they have quit for at least a week or two -- because the wound they leave will heal so poorly.

Smokers also have a higher risk of a number of diseases affecting appearance, including skin cancer, psoriasis, hidradenitis suppurativa, and thromboangiitis obliterans.