fight or flight

• Hypothalamus activates the adrenal medulla, part of the brain, which in turn activates the pituitary gland, triggering activity in the sympathetic branch of the autonomic nervous system.
• Adrenaline, a stress hormone, is released from the adrenal medulla, triggering a psychological change that leads to increased heart rate and is used in the fight or flight response.
• Sympathetic stage is characterized by physiological arousal and changes in the autonomic nervous system.
• Immediate and autonomic effects happen instantly and are an acute response and autonomic reaction.
• Sympathetic response leads to increased heart rate.
• Parasympathetic stage is a normal resting state.
• Parasympathetic action returns the body back to a resting state and reduces the body activity that were increased in the sympathetic stage.
• When a threat is perceived, the amygdala, the emotive part of the brain, is activated and sends a distress signal to the hypothalamus.
• The hypothalamus communicates with the sympathetic nervous system.
• Acute stress is short term and prepares for rapid action, causing a high spike in the Sympathetic nervous system.
• Chronic stress is ongoing and involves the HPA axis, where the hypothalamus will release a hormone called corticotrospin-releasing hormone (CRH).
• CRH is received by the pituitary gland, which releases adrenocorticotrophic hormone (ACTH).
• The adrenal cortex releases various stress-related hormone, cortisol.