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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.

MartianCactus
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  • 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. – kmm Aug 04 '16 at 18:11
  • 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? – MartianCactus Aug 04 '16 at 18:15
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    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. – WYSIWYG Aug 04 '16 at 18:47
  • @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? – MartianCactus Aug 04 '16 at 19:14
  • @Adi the gas has to eventually dissolve in an aqueous medium. How else would it reach the cells and mitochondria? – WYSIWYG Aug 05 '16 at 04:34
  • @WYSIWYG but.. can't it just reach it in gaseous form? – MartianCactus Aug 05 '16 at 07:00
  • How, in the form of bubbles??! – WYSIWYG Aug 05 '16 at 08:21
  • @WYSIWYG does diffusion only take place in water? – MartianCactus Aug 05 '16 at 08:59
  • No. Why are you making extreme assumptions?? Diffusion happens in any medium (except in perfect solids). Your body is made up of water and the reactions happening in your body need oxygen then how can it be in a different phase?? Diffusion doesn't need water. But all your cell stuff is suspended in water. Oxygen has to dissolve in water to be available to them. Gas bubbling through a liquid is not diffusion. The bubbles do not move according to diffusion gradient, they move according to surface tension/buoyancy. – WYSIWYG Aug 05 '16 at 09:10
  • @WYSIWYG ok now i understand. Thanks for the explanation. :) – MartianCactus Aug 05 '16 at 10:53

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