SAM pathway

• what is the sympathomedullary pathway?

  A fast response to acute stress
• How does the pathway work?


  Hypothalamus activates sympathetic nervous system, stimulated adrenal medulla to release into bloodstream, pituitary glands release noradrenaline, adrenaline bonds to adregenic receptors (alpha and beta)
• What does the pathway trigger?


  A fight or flight response
• What happens during the fight or flight response?


  Blood vessels constrict and divert resources to muscles and brain, pancreas stops secreting insulin to keep blood sugar levels high, liver and muscles convert glycogen to glucose at a higher rate
• How does adrenaline and noradrenaline affect the heart?

  Sympathetic arousal causes heart to work faster
• Timo Heidt (2014)


  Study on mice and medical staff. Thickened arteries and added stress increase the number of white blood cells. These cells produce small wounds, when the blood platelets rush to fill the wounds, there is an increased risk of blood clots which may induce a heart attack
• How is fight or flight linked to evolution?


  Ancestors were faced with situations which required an energetic response (facing a lion), we now experience fight or flight but no action is taken. This can cause problems to the body as we are left in a permanent state of arousal
• Jonathan Leor et al (1996) EVALUATION


  Found increased number of deaths caused by cariocaslaud problems on day of Northridge California Earthquake
• what is cardiomyopathy? EVALUATION


  Affects people who suffer severe emotional stress after an event. Paralyses bottom half of the heart, causes top half to work harder
• Dimsdale (2008) not a causal factor


  Must be cautious when we say stress causes heart disease, number of other factors involved (eg. Smoking)
• Taylor et al (2006) gender differences 


  Female stress response is tend or befriend. Release of oxytocin makes the individual more relaxed. When males are stressed, they release increased testosterone which dampens the effect of oxytocin
• Joe Tomaka (1996) challenge v threat


  If we see it as a challenge, our blood vessels are relaxed, if it is a threat our heart beats very fast