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Lecture 4 - Chapter 3 - Stress.docx

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Health Sciences
Health Sciences 1001A/B
Shauna Burke

Chapter 3: Stress Week 3 What is Stress?  Stress refers to: 1. Situations that trigger physical and emotional reactions – Stressor 2. The reactions themselves – Stress Response  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 stress  Responses to stressors include: 1. Physical Changes 2. Emotional and Behavioural Responses Physical Responses to Stressors  Two control systems are responsible for the physical response to stressors: 1. Nervous System 2. Endocrine System Nervous System Autonomic Nervous System  Part of the nervous system that is not under conscious supervision  Consists of two divisions: 1. Parasympathic Division  In control when you are relaxed  Aids in digestion, storing energy, growth promotion 2. Sympathetic Division  Activated during arousal and emergency situations (pain, anger, fear)  Releases norepinephine which commands body to mobilize energy resources to responds to crisis and causes arousal  Increase attention and alertness when released in the brain Endocrine System  The system of gland, tissues, and cells that help control body functions by releasing hormones and other chemical messengers into the bloodstream  Helps prepare the body to respond to a stressor Brain Detects Threat:  Neurochemical message sent to hypothalamus which releases chemicals to pituitary gland which releases adrenocoricotropic hormone (ACTH) into bloodstream  ACTH reaches adrenal glands which release cortisol and other key hormones into the bloodstream  Sympathetic nerves instruct adrenal glands to release the hormone epinephrine (adrenaline) which triggers several bodily changes o E.g. acute hearing and vision, increased heart rate, increased perspiration 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 o Positive stressors are stressors that are stressful but happening for a positive reason  Too exhausting for the body to remain in this state for long periods of time  Body returns to homeostasis o A state in which blood pressure, heart rate, hormone levels, and other vital functions are maintained within a narrow range of normal o Once a stressful situation ends the parasympathetic of the autonomic nervous system initiates adjustments necessary to restore homeostasis 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  Fight is aggression or confrontation  Flight is withdrawal Emotional and Behavioural Responses to Stressors Tend-and-Befriend  In addition to fight-or-flight, humans may respond to stress with social and nurturing behaviour  Especially characteristic of females o Female response to stress evolved to protect self and offspring  May depend on underlying biological mechanisms o E.g. hormone oxytocin Stress and Disease 1. The General Adaptation Syndrome (GAS)  Developed by Hans Selye (1936)  Stressors can be pleasant o Eustress  Stressors can be unpleasant o Distress  Sequence of physical responses is the same for both  First to differentiate positive and negative stress  Three reaction stages: 1. Alarm (initial stressor)  Included fight-or-flight response  Body is prepared to deal with crisis o More susceptible to disease  Symptoms are headaches, indigestion, anxiety, disrupted sleep and
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