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Chapter 3 - Stress.docx

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Health Sciences
Health Sciences 1001A/B
Shauna Burke

Stress: The Constant Challenge What is Stress?: Stress refers to: 1. Situations that trigger physical and emotional reactions = Stressor 2. The reactions themselves = stress response Stress: the general physical and emotional state that accompanies the stress response Responses to Stressors: - The primary determinant of the health consequences of stress is how the individual responds to the stress Responses to stress include: - Physical changes - Emotional and behavioural responses Physical Responses to Stressors: Two control systems are responsible for the physical responses to stessors: 1. Nervous system 2. Endocrine system Nervous System: - Autonomic nervous system - Sympathetic nervous system - Activated during arousal and emergency situation (pain, anger, fear) - Releases norepinephrine which commands body to mobilize energy resources to respond to crisis and causes arousal (increases attention and alertness) when released in the brain Endocrine System: - The system of glands, tissues, and cells that help control body functions by releasing hormones and other chemical messengers into the bloodstream - Help prepare the body to respond to a stressor Brain detects threats: - Neurochemical message sent to hypothalamus which releases chemical to pituitary gland which releases adrenocorticotropic hormone (ACTH) into the bloodstream - ACTH reaches adrenal glands which release cortisol and other key hormones into the bloodstream Simultaneously: - Sympathetic nerves instruct adrenal glands to release the hormone norepinephrine (adrenaline) which triggers several bodily changes - Examples include acute hearing and vision, increase in heart rate, increase in perspiration rate Fight or flight reaction (Sir Walter Cannon) **Physical changes vary in intensity but the same physical reactions occur in response to both positive and negative stressors Homeostasis - A state in which blood pressure, heart rate, hormone levels, and other vital functions are maintained within a narrow range of normal - Once a stressful situation ends, the parasympathetic division of the ANS initiates adjustments necessary to restore homeostasis Fight or flight in Modern Life - A survival mechanism that is part of our biological heritage - Not often necessary – many stressors we encounter do not require a physical reaction - Fight or flight reaction prepares the body for physical action regardless of whether it is an appropriate response Emotional and Behavioural Responses to Stressors: Tend and Befriend - In addition to fight or flight, humans may respond to stress with social and nurturant behaviours - Especially characteristic of females; female response to stress evolved to protect self and offspring - May depend on underlying biological mechanisms (e.g the hormone oxytocin) Stress and Disease: Explaining Stress and Disease: 1. The general adaptation syndrome (GAS) - Developed by Hans Selye (1936) - Stressors can be pleasant (Eustress) - Stressors can be unpleasant (Distress) - Sequence of physical response is some of both - Three reaction stages Stage 1: Alarm (initial stressor) - Includes fight or flight response - Body is prepared to deal with crisis (more susceptible to disease) - Symptoms = headaches, indige
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