When exposed to trauma, the body deploys its own defense system. 

From the first second the brain receives the signal that a catastrophe has happened, the blood rushes to the organs that need help the most. Blood floods into the muscles, the lungs, the heart, the brain. 

The brain makes a decision for the rest of the body. Either face the danger or run away. It's a mechanism designed to protect the body from harm. 

From knowing that what has happened might be irreparable, we call it 'shock'.

 When shock wears off, when the body can accept that a trauma has happened, when it can let down its defences, it's a scary moment. It's vulnerable. 

The shock response had protected us, and it just might have saved us.