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