The fight-flight response is initiated during countershock. The hypothalamus releases CRH (corticotropin-releasing hormone), which stimulates the anterior pituitary gland to release ACTH (adrenocorticotropic hormone) into the bloodstream. ACTH travels through the bloodstream and stimulates the adrenal glands, which produce adrenaline, noradrenaline and cortisol. Adrenaline and noradrenaline stimulate the sympathetic nervous system, which results in increased heart and breathing rate, blood pressure, etc. Cortisol stimulates the liver to increase release of glucose into the bloodstream.
Because the liver is releasing glucose, there is more available for the muscles to produce energy, so they can work a lot harder (eg. so we can run faster or punch harder). The heart beats faster so that the nutrients in the blood can be delivered to the muscles quicker. This is useful if we're trying to run away from a saber-tooth tiger or fight something, but isn't very helpful when the stressor is something like VCE
Essentially, because of this of this physiological arousal, our level of resistance to the stressor rises above normal, and we are more able to cope with it. If the stressor persists then we enter the stage of resistance. Physiological arousal decreases slightly but remains quite high, and our level of resistance to the stressor continues to increase. Cortisol remains at a high level in the bloodstream; although it helps keep our level of resistance to the stressor above normal, it also suppresses the immune system, so we become more susceptible to viral and bacterial infections.
Hope that helped
Home
Help
Search
Login
