Oxidative stress

[Adz795]

Well, I don't know much about this topic (I have tried searching the net but nothing gives me exactly the info. I want) so here are my questions:
1. What is oxidative stress?
2. What factors can cause oxidative stress in cells?
3. How is it combated? I guess peroxisomes play a role in it though it is unclear to me.
4. What are the effects of uncontrolled or too much of oxidative stress?

An explanation instead of a wiki link would be appreciated.
Thanks a lot.

[JackBean]

1) imbalance of redox environment in the cell or abundance of dangerous redox species (ROS etc)
2) - " -
3) peroxidases, superoxide dismutases, glutathion etc.
4) cell and cell parts damage (proteins, DNA, structures)