How closely related are the concepts of Karma and Pavlovian conditioning? If I get into a habit of fighting to defend "my self" is it reasonable to say that getting into a fight and getting beat up is karma? 

How similar is karma to the idiom "you reap what you sow"?
While habits are part of the workings of karma, it is not reasonable to say that what you described (habit to fight leads to beating) is Buddhist notion of karma. It may be correct other way around, though—some unwholesome karma is ripening while you exercise habit to fight.

Karma is similar to idiom "you reap what you sow" but with some added complexity. What you will reap is not need to be the same or feel the same as what you sow. In Buddhist concept of karma, unwholesome actions, when sown, will certainly reap into unwholesome fruits. What will be reaped is not mirror of what is sown, but it is consequence of what was sown. So when you sow action that should result in suffering, you will reap suffering for sure.