Re: What tissue repair processes causes blistering after sunburn?

Dear Kelly,

Blistering is caused by serum building up between the dermis and the 
epidermis in the skin, causing the two layers to separate.
They can be painful - as I am sure you know - and are caused by friction, 
by burns, by allergic reactions and by toxic chemicals.
Blisters caused by friction tend to be quite small and much debate has 
gone into whether it is best to burst them or not.  The consensus seems 
to be that is better to do so, using a sterile needle, and then to place 
a padded dressing (elastoplast or similar) over the site of the blister.  
Oh, and most important of all, to relieve the source of the friction!

Chemical blisters (such as those caused by mustard gas in WWI) and those 
caused by dioxin (Bhopal, India) are all over the affected area and can 
be very large indeed, when they are known as bullae.  

Blisters caused by burns can also be large and cause the body to 
dehydrate.  They used to be a major cause of death from burns, but modern 
treatements can normally replace this fluid loss.

The blister itself is the body's defence mechanism - the capillaries in 
the dermis swell and in doing so become more 'leaky'.  This allows both 
fluid (serm) and white blood cells to accumulate at the site and so 
helps to protect your body - not least, by being painful and so making 
you stop whatever caused the injury in the first place!
One of the chemicals that causes the capillaries to swell is histamine - a 
chemical produced whenever you are stung or bitten.  It is reponsible for 
the swelling around the site of the injury and anti-histamine creams 
relieve this.  To be most effective, you need to rub them on 30 mins 
BEFORE you get bitten/stung.............!
Hope that helps and that you were not injured by the blistering speed of 
thsi reply!
Ian (HD2)