Textbook Notes (369,074)
Canada (162,369)
HLTC22H3 (102)
Dan Silver (21)
Chapter 10

hltb01 chapter 10

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Health Studies
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Dan Silver

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Chapter 10 Stress coping and healthy Resistances to the adverse effects of stress may be the key to longevity as all of the antiaging genes appear to regulate cellbased stress resistance Stressy There are three major ways of defining stress o Physiological state of the organism sometimes referred to as strain 1 Classical theoriesCannon was the first physiologist to systematically describe the physiological effects of stress Cannon posited that the perception of a threat activated the sympathetic nervous system SNS which readies the organism for fight or flight He believed that threat activates the thalamus we now know that it is the hypothalamus that responds to stressThe SNS reacts to stress in two ways 1 The sympathetic nerves originate in the spinal column preganglionic nerves and radiate to the target organs postganglionic nerves The preganglionicnerves are cholinergic that is they secrete the neurotransmitter acetylcholine The postganglionic nerves are norepinephrine2 The second type of SNS response to stress is a little less direct In the sympatheticadrenal medulla SAM system the sympathetic nerves radiate to the adrenal medualla which is a small structure lying atop of the kidneys3 The effect of direct innervations on the various systems is faster but the route through the medulla can last up to ten times as long The two systems direct innervations and SAM are redundantan indicator of the importance of stressrelated SNS activation 4 Once the threat is resolved parasympathetic nervous system PNS activation returns the body to homeostasis by decreasing heart rate and respiratory rates as well as blood pressure and returning blood flow to the internal organs which promotes gastrointestinal activity1 Cannon argued that this fightflight reaction although adaptive in the short run could have very harmful effects if prolonged Eg Voodoo death 2 Cannon believed that the fightflight reaction is a general response to any stressor physical or social In reacting to sudden physical threats it is advantageous to be able to put up an aggressive defense or to run away very quickly3 Selye expanded on Cannons conceptions in two ways First he noticed that corticosteroids which are released by the adrenal cortex are also elevated in response to a wide variety of stressors
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