Stress And Disease Flashcards
Stress Definition
Stress is commonly defined as a state of real or perceived threat to homeostasis
What is Homeostasis
-Relatively constant internal balance of environment
-Defined as “set points” that keep cells in a normative state
Set points keep cells in normative state by providing:
-Optimal concentrations of gases, nutrients, ions, and water
-Optimal temperature for metabolism
-Optimal intracellular and extracellular fluid volumes
What is homeostasis maintained by
Negative feedback mechanisms designed to prevent significant changes from set post
Which 2 body systems control homeostasis
Nervous
Endocrine
Why is homeostasis important?
Maintains optimum cell structure (morphology) and functions (physiology) to maintain health of entire individual
Hemostasis is integral to
Healthy cellular functioning
Homeostasis must be somewhat ..
Flexible
Since small changes need to occur as cell metabolic activity increases or decreases to meet the body’s needs
Examples of when homeostasis changes
-Exercising
-Eating and digesting good
-Are examples where changes in BP,RR,HR or enzymatic and hormone secretion need to adjust to maintain homeostatic balance
Stressor
Any external or internal stimulus (variable) that causes a change in the internal homeostatic balance
-Thus created detectable homeostatic imbalances
2 Types Of Stressors
Distress
Eustress
Distress
-= bad stress, negative
-etiologies with potential for tissue damage
-e.g genetic, congenital, or acquired causes
Eustress
-=good stress, positive
-energizes, motivates
-Eg. Laughing, exercising, sleeping
Stress is a ___ event designed to..
Normal
-alert the body to potential issues, respond to those issues and then return to normal homeostatic balance
Different individuals and stress
Will be affected by and respond to the same type of stressor to different degrees
-why stress can manifest in many different psychological (behavioural/emotional) or physiological ways
Okay
Dealing with stress
Some suggest that previous life experiences of negative and positive stressors help to condition the individual to new stressors, enabling the individual to cope more efficiently
Categories of stressors affecting homeostasis
Chemical
Physical
Psychological
Chemical Stressors Examples of Internal Stressors
-Blood gases
-Water
-Ions
-pH
-Neurotransmitter
-Hormones
-Blood cell counts
-Hgb
-Nutrients
-Microbes (Infection)
-Drugs
-Inflammation
-Antibodies
Chemical Stressors Examples of External Stressors
-Low 02
-High CO2
-pollutants
-microbes
Physical Stressors Examples of Internal Stressors
-BP
-CO
-Urine
-Ventilation
-Body T
-Mechanical trauma (compression, obstruction, fracture)
-Excess weight gain or loss
-Mobility issues
-Age
Physical Stressors Examples External Stressors
-Air pressure
-Air T
-Mechanical trauma (sports injury, motor vehicle injury)
-Excess noise
-Excess light
-work hazards
Psychological (Emotional Stressors) Examples Internal Stressors
Pain
Fear
Anxiety
Psychological Stressors Examples External Stressed
Relationships
Family
Friends
Work
School
Homeostasis Negative Feedback
-A change from the normal set point of any of these variables would be detected by different body receptors and sent to a control centre (CNS of hypothalamus)
-The control Center would then send signals via effectors to respond to this change and return the variable towards the normal homeostasis state
An abnormal balance of any of these variables could result in
Disease or illness
Changes in internal or external environment variables can
Trigger a stress response
If change becomes permanent
Body cells will try to adapt
Chemical and physical changes are often
Measurable and used in diagnostics
Psychological/ behavioural changes are
Equally important but may be more difficult to measure
What is stressor is long term ?
Ie. chronic
-Then the body will attempt to adapt to the change
-Allostasis
Allostasis
The process of the adaptation to change
-If body cannot adapt, manifestations of chronic stress related disorders may occur
What is Homeostatic Imbalancd
-Normal homeostatic mechanisms are unable to return a physiological process to normal physiological set point
Neuroendocrine Responses
Will try to overcome the physiologic imbalance, reinstablish homeostasis
Moderate Chronic Imbalance
-Physiologic adaptive changes to the normal set point occur
-Includes compensatory mechanisms called Allostasis
-Clinical manifestations subtle/subacute or not observed
Severe and/or Chronic Imbalance
-Body not able to adapt to stress: Allostatic overload
-Clinical manifestations usually present
-Stress related illness, disease, death
How to imagine homeostatic imbalance
The teeter totter is stuck in one potion not adjusting back to normal homeostatic set point
What is Allostasis
-Process of cellular adaptations to chronic/constant change in the homeostatic set point of a variable
What is Allostasis mediated by
Changes (structural/physiological) in neuroendocrine, autonomic, and immune functions (new set point)
-Look for changes in neurotransmitter, hormone, and WBC responses
Allostasis is integral for
Cell survival to chronic homeostatic imbalance
Adaptation
The physiological and psychological (behavioural) processes utilized by the individual to respond to a stressor
Cellular Adaptations May be Used
-Diagnostically, and prognostically
Examples of Cellular Adaptations
-Dysplasia or anaplasia would be examples of cellular adaptations to chronic exposure to a carcinogen
-Development of atherosclerotic plaque in arteries is an example of cellular structural and physiological adaptations to chronic, turbulent, high P blood flow
-Insomnia is an example of psychological adaptations to chronic emotional and/or physiological stress
-Increased blood level of cortisol is an example of a physiological adaptation to chronic stress of any type
Examples of Stressors
-Environmental (work, home, neighborhood)
-Major life events
-Trauma, abuse
Individuals physiological responses to stress are determined by
A number of modifiable and non-modifiable risk factors
-These factors are the allostatic load that stimulates physiologic and/or psychologic responses
A persons ability to adapt to stress is
-Individualized
-Psychological stressors May elicit a physiological stress response and vice versa
Allostasis
Dynamic, adaptive structural, physiological and/or behavioural responses to stressors that can potentially change the homeostatic set point to a new “normal” range
-Often short term issue
Allostatic Load
-Individualized cumulative amounts of stressors that exist in our lives and affect our physiologic responses (genetics, lifestyle, daily or sudden events)
-The physiological and behavioural manifestations of these stressors are determined by our ability to adapt to the stress load, including various coping mechanisms
-May present with subtle clinical manifestations or none at all
Allostatic Overload
-The body is having difficulty managing the cumulative stressors and begins to manifest the effects of a loss of its reserves and its ability to continue to respond to and survive the stress
-Clinical manifestations should be present
-May lead to long term deficits, including stress related diseases
-Corresponds to the exhaustion stage of GAS
When does Allostatic Load become Allostatic Overload Example
-Individual experiencing chronic stress —> causes a prolonged increase in cortisol that the body must adapt to by subtly changing its physiology = minimal is any manifestations may be present for a long time —> Allostatic load —> stress persists —> eventually this increased cortisol manifests as increased BG, HR, BP and decreased immune function —> presence of clinical manifestations of stress related diseases —> Allostatic overload
Neuroendocrine system responds to
All stressors
Neuroendocrine system consists of
-1) neural structures
-2) endocrine structures
Neuroendocrine system neural structures
-Cerebral cortex (cognitive centers)
-Limbic system (survival centers)
-Reticular activating system (alerting centers)
-Hypothalamus (ANS control) d tf
Neuroendocrine System Endocrine Structures
-Hypothalamus (endocrine control Center) which releases hormones that regulate the pituitary gland + other endocrine glands hormone secretion
The body’s ability to elicit a stress response is
-Normal
-Allows the body to respond to and survive acute stressors
-Neurotranmitters and hormones released are quickly removed by enzymes as to not prolong chronic overstimulation that can cause damage
When the body cannot turn off the stress response ..
Problems start to occur
We call those problems stress related diseases
The hypothalamus..
-Controls the body’s physiological responses to stress
-May become aware of a stressor directly or be alerted to the stressor by higher brain centers
-Drives the neuroendocrine response to stress
Cerebral Cortex
-Prefrontal region
-Conscious thought, logic, reasoning, motivation, behaviour, personality
-Stress can create a stage of hyper vigilance, altered cognition, behavioural changes, and focused attention