Immune System. The Immune System Antigens are any substance (e.g., bacterial, viral, fungi) that can trigger an immune response. Bacterial – microorganisms.

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