The brain is the organ of anxiety, where anxiety both starts and is processed. Anxiety has two components- worry and fear. As such, both of these components of anxiety come from different parts of the brain. Worry is from the thinking part of the brain, which is located in the cortex, specifically the prefrontal cortex. Fear is from the emotional part of the brain, which is located in the limbic system, which includes the amygdala.
And the body is the recipient of the effects of anxiety. When you have the cortical function (prefrontal cortex- worry) and the limbic function (amygdala- fear) both activated, this in turn leads to a stress response from your body. This stress response comes from the fight or flight response, which is activated by the amygdala.
Thus, stress is a physical response to a threat, which can be real or imagined. The fight or flight response, with its activation of the sympathetic nervous system and release of adrenaline and cortisol, supercharges you to either fight or run from the danger. This stress response can go off even when there are threats that are not predators, such as job stress, relationship problems, and financial problems, just to name a few examples.
But the feeling of anxiety comes from both the brain and the body…anxiety is an uncomfortable feeling in the chest or abdomen (from the body), of fear, apprehension, or dread (from the brain). Often there are physical symptoms of anxiety. And there is a sense that something bad will happen. So anxiety is the culmination of worry, fear, and stress (see box below):
Components of Anxiety
repetitive circular thinking, rumination (cortical
feeling induced by worry or thoughts about a threat
a physical response for survival- fight or flight (body
Anxiety = Worry + Fear + Stress
Anxiety- an uncomfortable feeling of dread or fear,
felt in the chest or abdomen
So to summarize, the brain is the organ of anxiety, where worry comes from the thinking part of the brain (cortex), and fear comes from the emotional part of the brain (limbic system, amygdala). And the body is the recipient of the effects of anxiety, where the amygdala triggers the fight or flight response. This is the stress response of the body to anxiety, which prepares the body to either fight or run from the threat, which can be real or imagined, and the threat does not have to be a predator. External stressors can also set off this stress response.
So it is this cascade of worry, fear, and stress response which culminates in anxiety, which is an uncomfortable feeling of fear or dread, felt in the chest or abdomen. Thus, anxiety involves both the brain and the body, with the sense that something bad will happen and the associated physical symptoms of anxiety.