Why does acid reacts with skin??

I can understand the acid would react with blood as it is alkaline in nature. But when i googled pH of skin, its around 4-5, "it is estimated that the 'natural' skin surface pH is on average 4.7, i.e. below 5"(Reference) The thing that i could guess is that only H+ are the ions that would react with our skin since only H+ are common in every acid. But since our skin is also acidic how will an acid react with another acidic material

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    $\begingroup$ The shortest answer I could give is that not every molecule in a skin cell is acidic. Many biomolecules are also prone to hydrolysis under strongly acidic conditions $\endgroup$ – orthocresol Oct 1 '15 at 8:23
  • $\begingroup$ but what about dil. sulfuric acid or dil. acetic acid. acetic acid is even less acidic but there is still burning sensation with a bit if conc. acetic acid $\endgroup$ – Chinmay Chandak Oct 1 '15 at 8:46
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    $\begingroup$ 1 molar (that is: dilute) sulphuric acid still has a pH of approximately zero, so for sure it will react somehow. Acids can react with much more than ‘just’ alkaline solutions. $\endgroup$ – Jan Oct 1 '15 at 12:23
  • $\begingroup$ isn't the question narrow enough to answer??? it is as simple that "why does acid reacts with our skin to give burns?" :( $\endgroup$ – Chinmay Chandak Oct 1 '15 at 16:28
  • $\begingroup$ Acids first participate proteins in the skin to form a barrier. Alkali compounds tend to digest tissue and penetrate deeper into the skin/body. $\endgroup$ – MaxW Oct 23 '15 at 7:10