The adrenal medulla is an endocrinal gland that secretes catecholamines in response to stress, fear or anger. Catecholamines oppose some physiological actions such as increasing the heart rate and elevating the blood pressure which helps the body adapts to stressful situations.
peripheral and metabolic responses
The nervous system regulates the activity of muscles and glands via electrochemical impulses delivered by neurons, and those organs respond within milliseconds. The endocrine system influences metabolic activity by means of hormones, which are chemical messengers released into the blood to be transported throughout the body. Binding of a hormone to cellular receptors initiates responses that typically occur after a lag period of seconds or even days. The responses tend to be much more prolonged than those induced by the nervous system.
Ian Gordon Campbell has written: 'The influence of spinal cord injury on the physiological and metabolic responses to exercise and performance'
The heart beats more rapidly, blood flow to the brain increases.