When i get upset and stressed out i start getting shaky and light headed. why do you suppose this is happening?

Adrenaline: When you are upset, your body thinks something is really wrong and releases adrenaline. This caused the "fight or flight" reaction, and your body is immediately ready to respond to the danger. The extra drenaline is what is causing you to shake. You can also begin to hyperventilate, breathing out too much carbon dioxide too fast, causing light headedness. You need to learn some stress reduction.