Stress

• Stress


  Bodily response to any form of noxious stimulus
• Homeostasis


  The purposeful maintenance of a stable internal environment
• Homeostasis


  1. Sensor

  2. Stressor

  3. Integrator

  4. Effectors
• Feedback systems


  Control systems operate by negative feedback mechanisms
• Stress


  A state manifested by a specific syndrome of the body developed in response to any stimuli that made an intense systemic demand on it
• Stress response


  Body's attempt to adapt to stimuli
• Selye's General Adaptation Syndrome

  Involves 3 stages
• Stressors


  Events or environmental agents that initiate the stress response
• Types of stress


  • Eustress
  • Distress
• Manifestations of stress response

  • Mobilization of energy
  • Sharpened focus and awareness
  • Increased cerebral blood flow and glucose utilization
  • Enhanced cardiovascular and respiratory functioning
  • Redistribution of blood flow to the brain and muscles
  • Decreased immune function
  • Inhibition of reproductive function
  • Decrease in appetite
• Neuroendocrine components of the stress response


  1. Cerebral cortex

  2. Limbic system

  3. Thalamus

  4. Hypothalamus

  5. Pituitary gland

  6. Reticular activating system
• Neuroendocrine responses to stress (see Table 7-1)
• Neuroendocrine response: Locus Coeruleus


  Area of brainstem that produces norepinephrine and is a central integrating site for the autonomic nervous system response to stressful stimuli
• Neuroendocrine response: "Fight or flight"


  Sympathetic nervous system manifestation of the stress reaction
• Sympathetic activity in the "fight or flight" response


  • Increases attention and arousal
  • Intensifies memory
  • Increases heart and respiratory rates
  • Causes hands and feet to become moist
  • Dilates pupils
  • Causes mouth to become dry
  • Decreases activity of the gastrointestinal tract
• The exact mechanism by which stress produces its effect on the immune response is unknown
• The quantity and quality of immune expression is changed because of stress
• Coping and adaptation to stress


  Mechanisms that evolved for organisms to respond to or modify their environments, habits, or both to achieve a way of life that is best suited to their needs
• Adaptation


  An individual has successfully created a new balance between the stressor and the ability to deal with it
• Coping strategies or mechanisms


  Depend on how we perceive and interpret the event
• Adaptive capacity


  Stressors tend to produce different responses in different persons or in the same person at different times
• Conditioning factors affecting adaptation


  • Internal
  • External
• Factors affecting adaptation


  • Is the event perceived as a threat of harm or loss?
  • Is the event perceived as a challenge rather than a threat?
  • Physiologic reserve
  • Time
  • Genetics
  • Age
  • Health status
  • Nutrition
  • Circadian rhythm
  • Hardiness
  • Psychosocial factors
• Physiologic reserve


  The ability of body systems to increase their function given the need to adapt
• Anatomic reserve


  Paired organs that are not needed to ensure the continued existence and maintenance of the internal environment
• Acute stress results from psychologically or physiologically threatening events
• Reactions to acute stress


  • Arousal
  • Alertness
  • Vigilance
  • Cognition
  • Focused attention
  • Appropriate aggression
• Effects of acute stress


  • Mood disorders
  • Anxiety
  • Depression
  • PTSD
  • Eating disorders
  • Sleep disorders
  • Diabetes type 2
  • Hypertension
  • Infection
  • Exacerbation of autoimmune disorders
  • Gastrointestinal problems
  • Pain
  • Obesity
  • Eczema
  • Cancer
  • Atherosclerosis
  • Migraine
• Effects of chronic stress


  • Pathophysiologic changes occur leading to dysfunctional negative feedback system
  • System can become overactive or underactive
  • Leads to altered physiological function in cardiovascular, gastrointestinal, immune, neurologic systems
  • Altered psychological factors like depression, accidents, suicide, chronic alcoholism, drug abuse, eating disorders
• Posttraumatic stress disorder (PTSD)


  Caused by chronic activation of the stress response as a result of experiencing a significant traumatic event
• Trauma may impact memory in PTSD
• PTSD was formerly called "battle fatigue" or "shell shock" because it was first characterized in men and women returning from combat
• Causes of PTSD


  • War
  • Major weather-related disasters
  • Airplane crashes
  • Terrorist bombings
  • Rape or child abuse
  • Accidents
• Characteristics of PTSD


  • Experienced, witnessed, confronted a traumatic event that resulted in horror or fear
  • Triad of symptoms for at least 1 month: intrusion, avoidance, hyperarousal
  • Caused clinically significant distress
• The pathophysiology of PTSD is not completely understood