What causes anxiety and panic attacks?

Apply critical thinking to topic of anxiety and panic attacks. What causes them What happens in the brain chemistry What part of the brain causes anxiety and panic disorders Is anxiety caused by a chemical imbalance in the brain and how are environmental factors play a role. The discipline is psychology so I need to gear the paper more towards how the brain deals with these issues and how they affect our daily life. More important what causes them to develop in our brain. Although the environment we live in definitely has an effect on how people feel and deal with daily life, it is important to consider the biological factors leading to social anxiety disorder —-( thesis)