The Sympathomedullary Pathway


1. stressors arouse autonomic nervous system (ANS)

ANS = parasympathetic branch = returns animal to state of relaxation

          sympathetic nervous system (SNS)= arouses animal for fight or flight

Sympathomedullary pathway = SNS + SAM (sympathetic adrenal medullary system)


  • neurones from SN travel to almost every organ and gland within the body - preps body for action necessary when animal is under threat.

Responses = increased heart rate, blood pressure, pupil size and metabolic changes

Noradrenaline: neurotransmitter released by SNS to activate internal body organs.


at the same time SNS is activated, SAM system alerts animal through release of adrenaline into bloodstream.


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