burning skin question and diffusion of water/salts

[dudewheresmymd]

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p. 199 EK states: "burning of skin can increase this type of water loss dramatically" what do they mean by this?

2) water and salts do they diffuse through channels in the skin? is this a passive process?

3) what is the precursor to vitamin D called that is activated by enzymes in the liver/kidney to produce vitamin D? EK doesn't mention it's name.

 

[Blueprint MCAT Tutor]

1. You lose more water. Not really sure about your question here. It says you lose 0.25 to 0.5 L of water each day through diffusion out your skin. If your skin is burned, you lose more.

2. The book just says "diffusion" so I assume they're not referring to channels. If there were channels, it would be facilitated diffusion. Yes, it's passive because all diffusion is passive.

3. http://en.wikipedia.org/wiki/Vitamin_D#Biosynthesis 😛

 

[dudewheresmymd]

1. You lose more water. Not really sure about your question here. It says you lose 0.25 to 0.5 L of water each day through diffusion out your skin. If your skin is burned, you lose more.

2. The book just says "diffusion" so I assume they're not referring to channels. If there were channels, it would be facilitated diffusion. Yes, it's passive because all diffusion is passive.

3. http://en.wikipedia.org/wiki/Vitamin_D#Biosynthesis 😛

Gotcha, I think I saw an mcat question once that said more plaques on the skin from severe burns prevents water loss? I guess they're just talking about light burns here?


Thanks!

 

[jlescher]

There is no way you will need to know the precursor for vitamin D for the real test. Just know that vitamin D is a derivative of cholesterol and not a protein, for example.

 

[dyspareunia]

1. You lose more water. Not really sure about your question here. It says you lose 0.25 to 0.5 L of water each day through diffusion out your skin. If your skin is burned, you lose more.

2. The book just says "diffusion" so I assume they're not referring to channels. If there were channels, it would be facilitated diffusion. Yes, it's passive because all diffusion is passive.

3. http://en.wikipedia.org/wiki/Vitamin_D#Biosynthesis 😛

1. .
2. All water moves passively, aquaporins or not. There is no active water transport.
3. liver enzyme = 25-hydroxylase, kidney enzyme = 1-a-hydroxylase

Gotcha, I think I saw an mcat question once that said more plaques on the skin from severe burns prevents water loss? I guess they're just talking about light burns here?


Thanks!

Burned skin = no barrier keeping water in, thus you lose more water.
Plaques = water can't diffuse out because of fibrosis.