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My teacher told me the other week, that respiration through skin (cutaneous respiration) cannot happen without moist skin. That is why frogs have moist skin.

My question- Why does cutaneous respiration needs moist skin? Can't it happen on dry skin?

ALSO - Why does cutaneous respiration happen in the first place? It uses diffusion right? And diffusion doesn't produce enough energy for an organism as big as a frog to live does it?

Please help.

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  • $\begingroup$ Cutaneous respiration does take place through dry/keratinous skin to some extent, so I think it's an overstatement to say that it cannot happen. The answer to your first question is in your second question: diffusion. Think about the similarities of moist skin to the epithelial lining of the lungs. $\endgroup$
    – kmm
    Aug 4, 2016 at 18:11
  • $\begingroup$ They are both moist and uses diffusion right? But the lungs have millions of allveoli (700 millions if I remember correctly) which helps in more surface area. BUT why does diffusion need water? It just refers to substances going from area of high concentration to low concentration right? Why does it need moisture(water) then? $\endgroup$ Aug 4, 2016 at 18:15
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    $\begingroup$ The gas has to diffuse to an aqueous medium in order to be absorbed by the body (the entire body has an aqueous medium). How can a dry skin ensure that? It would just pose as an additional barrier to diffusion. $\endgroup$
    – WYSIWYG
    Aug 4, 2016 at 18:47
  • $\begingroup$ @WYSIWYG i dont understand. It should be easier for oxygen to diffuse as a gas shouldn't it be? Gases are more "fluid" and movement is easier. How does aqueous solution facilitate diffusion more than air then? $\endgroup$ Aug 4, 2016 at 19:14
  • $\begingroup$ @Adi the gas has to eventually dissolve in an aqueous medium. How else would it reach the cells and mitochondria? $\endgroup$
    – WYSIWYG
    Aug 5, 2016 at 4:34

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