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
Foreignmaterial
CoughSneeze
Phagocytesengulf it
Th
cells
Interlukin-2Tc cellsB cells
Gamma-interferon
Interlukin-1
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
Raise arousal
Optimal Arousal
Reduce arousal
Arousal0 50 100
Att
enti
on
50
100
Health Belief Model
PerceivedSeverity
PerceivedPros of action
PerceivedCons of action
ActionLikelihood
PerceivedSusceptibility
High
Low
High
Low
Perceivedthreat
High
Low
High
Low
High
Low
High
Low
Health Belief Model Predicts: Preventative dental care Breast self-examination Weight management AIDS risk-related behaviours Participation in health risk
screening programs
Efficacy BeliefsResponse
Efficacy
one’s confidence in the effectiveness of reduction methods
Self Efficacy
one’s confidence in using these 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 BehaviourAjzen & Fishbein, 1986
Response-Efficacy
High
Low
Self-efficacy
High
Low
Value ofOutcome
High
Low
SubjectiveNorms
High
Low
Intentions
High
Low
BehaviourChange
High
Low
Univariate Predictors of Non - Adherence to Cancer Screening
Self-PerceivedRisk ImmediatePost-Counselling
Number (%)Adherent
Number (%)Non-adherent
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)
Precontemplation
Preparation
Contemplation
Maintenance
Action
Relapse
Processes of ChangeProchaska et al. 1992
Precontemplation Contemplation Preparation Action Maintenance
Consciousnessraising
Dramaticrelief
Environmentalre-evaluation
Self- re-evaluation
Pros & cons
Self-liberation
Trial & error
Reinforcementmanagement
Helpingrelationships
Counter-conditioningStimulus control