How do enzymes denature, and what is the effect on the human body?

Answer 1

This is an educated guess using info thati already know and applying it, so it will probably need a 2nd opinion.

Enzymes denature when they are introduced to too much heat because it breaks the hydrogen bonds in their 3D-globular structure (If you've learnt about that you should know).
This means that their structure isn't as it should be and so they cannot carry out the reactions they're meant too. The more heat added the more they denature (as the more bonds break in the 3D structure).
Some enzymes can still work when partially denatured as the active site can still bind to the substrates.

I'm guessing that Enzymes denature when introduced to an acid/base because the H+'s in the acid and OH- in the base will tear the enzyme apart.