Physiological changes refer to automatic reactions that take place in our body in response to some stimulus, for e.g., if you saw a snake, the brain at the cognitive level perceived the stimulus as dangerous. This leads to physiological arousal such as dilated pupils, increased heart rate, increased pulse rate, sweating. At the emotional level you experience fear. The Autonomic Nervous System and Glandular system signal the pituitary gland which activates the adrenal glands to secrete the cortisol hormone. This triggers “the fight or flight” response. At the behavioural level there is an action plan such as running away or calling for help, etc.
