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simple diffusion and skin cells

For discussing the functions of different structures of all organisms.

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simple diffusion and skin cells

Postby Biology teacher » Sun May 13, 2007 7:37 pm

Hi

I wonder why can't skin cells or eye cells take oxygen directly from the surrounding air by simple diffusion ?
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Postby kotoreru » Sun May 13, 2007 9:18 pm

I could be wrong, but I believe skin cells do permit gas diffusion to a point. This is why painting someone's body entirely in paint is a really bad idea.

As for the eye, well the sclera is a thick layer of protein (isnt it?) so its not cells that are obstructing gas.
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Postby James » Mon May 14, 2007 11:22 pm

When amniotes evolved keratinized skin to avoid dessication the ability to do cutaneous exchange was hindered and almost completely lost. The skin is too thick, and pretty much impermiable.
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Postby xand_3r » Sat Jun 02, 2007 10:46 pm

About 1% of respiration occurs through skin. This is an extremely low value if you take in consideration that the skin is almost always in contact with air and it has a very large surface. Skin is impermeable to water and solutes but liposoluble substances (including gases) can pass.
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Postby Tae Jun, Yoon » Sun Jun 03, 2007 7:18 am

Well, as you know diffusion of gas like oxygen occurs through phospholipid in cell membrane. As I know, most of membrane of skin cell doesn't contact with outer environment - They are protected by protein. I think Oxygen can't penetrate the protein.
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Postby Darby » Sun Jun 03, 2007 7:57 pm

As I understand it, the surface cells can take in enough oxygen from the air to keep themselves alive (they are quite a distance from their blood vessels); skin cells die as they dehydrate, but corneal cells have blinking and the aqueous humour to keep them hydrated (but how they stay nourished I'm not sure).
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