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Immune System

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					Immune System
The Immune System
   Antigens are any substance (e.g., bacterial,
    viral, fungi) that can trigger an immune
    response.
   Bacterial – microorganisms in the
    environment. Grow rapidly and compete with
    our cells for nutrients.
   Fungi – organisms like mould and yeast.
    Also, absorbs nutrients.
   Viruses – proteins and nucleic acid. They
    take over the cell and generate their own
    genetic instructions.
Immune System
   Immune system recognizes itself and
    foreign material
   Transplant success can by increased by:
       Using close genetic tissue match.
       Using medications that inhibit the immune
        system’s attack on the foreign material.
Immune System
   Allergies are immune response to
    (normally) harmless substances.

   Allergins are substances that trigger an
    allergic response (e.g., pollen, cat
    dander)
Organs of the Immune System
   Lymphatic and lymphoid organs
       Deploys lymphocytes
   Lymphocytes
       White blood cell that provides main
        defense against foreign material
       Produced by bone marrow
    Organs of the Immune System
   Lymph Nodes
       Bean-shaped spongy tissue
       Largest are in the neck, arm-pit, abdomen, and
        groan
       Filters to capture antigens (foreign material) and
        has compartments for lymphocytes.
   Lymph vessels
       Connects to lymph nodes and carries fluid called
        lymph into the blood stream
Organs of the Immune System
   Lymphocytes
       Form of white blood cells that provide main
        defense against foreign matter
   Lymphocytes originate from bone
    marrow
        Organs of the Immune System

   Spleen
       Upper left side of the abdomen
       Filters antigens that the lymph vessels put
        into the bloodstream
       Home base for white blood cells
       Removes worn out red blood cells
Organs of the Immune System
   Phagocytes
       Engulf and ingest antigens
   Two types:
       Macrophages – attach to tissue and stay
        there
       Monocytes – circulate in the blood
   Nonspecific immune processes
Specific Immune Processes
   Cell-mediated immunity
   Killer t-cells (CD8) – destroy foreign
    tissue, cancerous cells, cells invaded by
    antigens
   Memory t-cells – remember previous
    antigen in order to defend against
    subsequent invasions.
    Specific Immune Processes
   Delayed hypersensitivity t-cells – involved in
    delayed immune reactions. Produce
    lymphokines that stimulate other t-cells to
    grow, reproduce and attack.
   Helper t-cells (CD4 cells) – get information of
    invasions and report to spleen and lymph
    nodes to stimulate lymphocytes for attack.
   Suppressor t-cells – slow down or stop
    immune processes.
Immune System
   Antibodies – proteins produced in the
    body in response to antigens. They
    combine chemically with antigens to
    overcome their toxic effects.
   B lymphocytes – secrete antibodies
    that protect body against bacterial
    infection and viral infections.
Immune System
   T lymphocytes – produced by the
    thymus gland and is a slower acting
    response.
   T cells secrete chemicals that kill
    invading organisms. Two types:
       Cytotoxic T (Tc cells)
       Helper T (Th cells)
   Immune Response
Foreign    Cough        Phagocytes           Interlukin-1
material   Sneeze       engulf it

                                     Th
                                     cells



           Gamma-                 Interlukin-2
           interferon   B cells   Tc cells
Immune System – Other
organs
   Tonsils
   Thymus gland
    Why Can’t We Fight Cancer
   Some cancer cells release substances
    that suppress the immune response.

   Some antigens may be difficult for the
    immune system to recognize.
    Less Than Optimal Defenses
   Immune function changes during the lifespan,
    increasing in childhood and decreasing in old
    age.
   Unhealthy lifestyles impair immune
    functioning
       Insufficient vitamin A or E decrease production of
        lymphocytes and antibodies
       Vitamin C in important in effectiveness of
        phagocytes
       High fat and cholesterol intake impair immune
        functioning
       Poor sleep impairs immune functioning
Diseases of the Immune
System
   AIDS
   Elephantiasis
   Tonsillitis
   Mononucleosis
   Lymphoma
Diseases of the Immune
System
   Autoimmunity Disorders
       Immune response attacks its own tissue
   Arthritis
   Multiple sclerosis
   Systemic lupus erythematosis
     Stress and the Immune
     System
   Stress appears to suppress the immune
    response.
   Killer T-cells are lower during periods of high
    stress.
   Adrenaline and cortisol that are released
    during stress appear to increase suppressor
    T-cells, decrease helper T-cells, and decrease
    functioning of phagocytes and lymphocytes.
   Chemicals released by our nerves suppress
    immune functioning in nearby cells.
Health Behaviours
Three most common health
protective behaviours
   Healthy eating
   Sufficient sleep (7 – 8 hours nightly)
   Keep emergency phone numbers by the
    phone.
   Most people do not watch their weight,
    get enough exercise, limit fat and
    caffeine, and use seat belts.
Health Promotion
   Developing and maintaining healthy-
    promoting behaviours in individuals of all
    ages.

   Reducing or eliminating health-damaging
    behaviours.

   Helping people at risk for a particular health
    problem develop and maintain health
    behaviours that will help reduce their health
    risk.
    Health Promotion
   Individual level
   Societal level
   Mass media
   Primary prevention – intervening to modify
    behaviours before the diseases begin
   Secondary prevention – intervening to modify
    behaviours to prevent progression of disease.
     Four things we know about
     health behavious

   Health habits are fairly stable, and do not
    change over time.
   Health protective behaviours are not strongly
    related to each other.
   Health protective behaviours are not
    controlled by a single set of response
    tendencies or attitudes.
   Factors influencing health behaviours can
    vary across individuals.
     Factors within Individuals that
     influence health behaviours
   Many health behaviours are less pleasurable
    than unhealthy alternatives.
   Adoption of new behaviours may require
    changing longstanding habits.
   When healthy there’s little incentive to
    change a problem behaviour.
   No certainty that you will suffer the negative
    consequences of problem behaviour.
   Need skills and knowledge to change.
    Interpersonal Factors in
    Health Behaviours
   Whether your friends and family
    perform the behaviour.

   Whether you have social support and
    encouragement to perform the
    behaviour.
Social Factors in Health
Behaviours
   Social/cultural norms

   Community resources

   Legislation
     Social, Personality, and
     Emotional Factors
   Support from significant others
   Conscientiousness
   Stress
   Neuroticism
   Perception
   Cognition
   Beliefs
Communication Messages
   Colourful, case histories, and emphasize the
    benefits of a health behaviour change.
   Expert, trustworthy communicator
   Strong messages at beginning & end
   For illness detection, emphasize “loss frame”
   For health promotion, emphasize “gain
    frame”
   Moderate fear arousal
                     U - Shaped Arousal Curve
       100


                            Optimal                 Arousal
Attention




            50

                     Raise arousal                    Reduce arousal




                 0                             50                  100
                                     Arousal
   Health Belief Model
Perceived                    Perceived
Susceptibility               Pros of action
                               High
   High                                       Action
                 Perceived
                 threat         Low           Likelihood
  Low
                  High                         High
                             Perceived
Perceived                                      Low
                   Low       Cons of action
Severity
  High                            High
                                  Low
   Low
Health Belief Model Predicts:
   Preventative dental care
   Breast self-examination
   Weight management
   AIDS risk-related behaviours
   Participation in health risk screening
    programs
Efficacy Beliefs
Response               Self Efficacy
 Efficacy
                          one’s confidence
   one’s confidence       in using these
    in the
    effectiveness of       methods
    reduction
    methods
      Key Factors In Changing
             Behaviour
   You have to want to do it (motivation)
   Feel you have the right method
    (response efficacy)
   Feel relatively confident about being
    able to use this method (self-efficacy)
    Theory of Planned Behaviour
    Ajzen & Fishbein, 1986
Response-   Value of
Efficacy    Outcome
  High       High
                         Intentions   Behaviour
   Low        Low                     Change
                          High         High
            Subjective
Self-
            Norms          Low         Low
efficacy
 High        High
              Low
  Low
 Univariate Predictors of Non -
 Adherence to Cancer
 Screening
   Self-Perceived         Number (%)    Number (%)
   Risk Immediate         Adherent      Non-adherent
   Post-Counselling
   Low                     18 (72.0%)     7 (28.0%)

   Medium                  28 (71.8%)    11 (28.2%)

   High                     7 (36.8%)    12 (63.2%)

X2 (2) = 7.79, p < 0.02
Other Interventional Models
for Health Behaviour Change
   Cognitive-behavioural model –
    modifying irrational beliefs or beliefs
    that undermine behaviour change
   Self-observation and self-monitoring
   Classical conditioning
   Systematic desensitization
Other Interventional Models
for Health Behaviour Change
   Operant conditioning (reinforcement
    and punishment)
   Modeling
   Stimulus control
   Homework assignments
   Relaxation training
          Transtheoretical Model
                                            (Prochaska & DiClemente, 1992)




                              Preparation


              Contemplation                  Action



Precontemplation                                         Maintenance

                              Relapse
       Processes of Change
       Prochaska et al. 1992

 Precontemplation Contemplation    Preparation   Action   Maintenance



Consciousness                                             Reinforcement
raising                                                   management

Dramatic           Self-              Self-               Helping
relief             re-evaluation      liberation          relationships

Environmental      Pros & cons        Trial & error       Counter-
re-evaluation                                             conditioning
                                                          Stimulus control

				
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posted:3/27/2008
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