Stress & Adaptation Flashcards
Homeostasis
-State of constancy
-Requires feedback control systems
-Integrates a variety of body systems
Cannon’s 4 features:
-Mechanisms to maintain constancy
-Change from “steady-state” causes a response
-Response is multifactorial & cooperative
-Simultaneous or successive
“Organized self-government”
Eustress
Controllable (mild/brief) periods of stress contributing to emotional and intellectual growth
Allostasis
Interactive physiologic changes in neuroendocrine, autonomic, and immune systems in response to real or perceived challenges/threats to homeostasis
It increases chance of survival!
Stress Definition
“A state manifested by a specific syndrome of the body developed in response to any stimuli that made an intense systemic demand on it”
Endogneous & Exogenous Stress
Stressor
- Endogenous (within the body)
- Exogenous (outside the body)
Response to stress dependent upon:
- Properties of stressor
- Condition of person being stressed
Factors affecting condition are:
- Internal (genetic, age, gender)
- External (environmental exposure, life experiences, dietary, social support)
General Adaptation Syndrome Stages
- Alarm Stage
- SNS & HPA axis stimulation
- Release of catecholamines & cortisol - Resistance Stage
- Body responds and adapts
- Cortisol levels drop - Exhaustion Stage
- Resources are depleted
- Damage to systems if prolonged
Neuroendocrine System Response
- Release of neurohormones result in
- Energy
- Sharpened focus & awareness
- Increased cerebral blood flow and glucose utilization
- Enhanced CV & respiratory function
- Shunting of blood to brain/muscles
- Modulation of immune response
- Inhibition of reproductive function
- Decreased appetite
Neurohormones involved in stress
Catecholamines
Cortisol:
- Potentiates epinephrine and glucacon
Decreases non-essential energy-using activities (metabolic rate, reproductive, osteoblasts, rbc/wbc production, immune system)
Angiotensin II
Aldosterone
ADH
Sympathetic System—“Fight-or-Flight”Response
- Rapid response to trauma and emergency
- Epinephrine & norepinephrine both released
- Both attach to adrenergic receptors on cells
- Blood pressure restored
- Blood flow to skin, guts, and kidneys reduced
- Skin becomes pale
- Urine production decreases
- GI activity decreases
look at slides 12 & 13
Cortisol—The “Stress Hormone”
- Helps regulate the stress response
- Diverts metabolism from building to supplying energy for dealing with the stress
- Causes signs and symptoms of chronic stress
- Alters glucose, fat, and protein metabolism
- Suppresses inflammatory and immune response
Effect of Stress on Immune System
- Decreased immune cell production
- Decreased thymus activity (eventual atrophy)
- Fewer t-lymphocytes
- Monocytes/lymphocytes release inflammatory mediators and cytokines which interfere with brain activities
- Exact mechanisms unclear
- Variable from person-to-person
Adaptation
-The ability to adapt is influenced by coping mechanisms /strategies, both emotional & behavior , attempting to maintain physiologic and psychosocial homeostasis
Factors affecting ability to adapt
- Time available to adapt
- Genetic endowment/acquisition
- Age
- Gender
- Health status
- Nutrition
- Sleep-wake cycles
- Hardiness (ability to conceptualize stressors as a challenge rather than a threat)
- Psychosocial factors (support/family/friends)
What Can The Acute Stress Response be Caused by?
- Threat to physiologic environment
-Moment-to-moment feedback mechanisms specific to threat
Eg: baroreceptors response to position change - Threat to psychosocial environment
-Response is not specific, and therefore may be inappropriate and sustained
Eg: death of family/friend/pet
Affects of Acute Stress
ANS result in arousal, alertness, vigilance, cognition, focused attention, appropriate aggression
If pre-existing health issue, ANS is already “pushed”
HPA axis response is crucial
Resultant hyperglycemia is not understood well but results in poorer outcomes for serious illness
Low-dose insulin has positive effect
If healthy, redirection of health-promoting activities may (will?) result
Chronic Stress Response
Occurs when
Component of system fails
Original stimulus is prolonged/adaptation exhausted
Results in over-reaction or under-reaction
Examples of chronic stress manifestations: Necrotizing gingivitis Herpes Simplex Virus (HSV) 1 Rhinovirus infections Exacerbation of any disease process
Posttraumatic Stress Disorder (PTSD)
-Chronic activation of stress response d/t significant traumatic event
-Traumatic event = actual or threatened death/major injury
Combat
Major accident/bombing
Environmental
Rape
Child abuse
PTSD patho
- Increased levels of catecholamines & thyroid hormones
- Decreased cortisol levels
- Symptom Triad
- Present together x 1 month /and/
- Clinical symptoms or functional impairments
PTSD Symptom Triad
- Intrusion
- Flashbacks/nightmares of event - Avoidance
- Emotional numbing
- Depression
- Survivor guilt - Hyperarousal
- Irritability/anxiety
- Exaggerated startle reflex
- Difficulty concentrating/memory problems
- Increased concern over one’s safety
- Sleep disturbances
PTSD increases risk for…
Depression Panic disorder Generalized anxiety disorder Substance abuse Physical illnesses (e.g. HTN, asthma, chronic pain syndrome)
Treatment options for PTSD
Main Goals - Avoid poor coping behaviours - Provide stress-reducing strategies Relaxation Techniques Guided Imagery Music Therapy Massage Therapy Biofeedback
Factors affecting the ability to adapt
> Physiologic Reserve -Ability of the body systems to increase their function RBCs, HR, vasodilation/constriction > Anatomic Reserve -Paired organs
