Neuro transmitters release fro our brain known as catecholmines know as epinephrine and norepinephrine, and released from the nerve endings of the sympatheic nervous system. Catecholamines stimulate receptors in the body known as adrenergic receptos. It these catecholamines bind to these adrenergic receptors, they will create what we know as the "flight or fight". WHen this haooens we will see an increase in our heart rate, an increase in our heart rate, an increase in our blood pressure, an increase in muscle contractions, and a relaxtion of smoot muscle of the bronchial tubes of the respiratory system, which allows us to expland our lungs easier to take in more oxygen.