Transcript Powerpoint

Immune System
The Immune System
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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
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Immune system recognizes itself and
foreign material
Transplant success can by increased by:
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Using close genetic tissue match.
Using medications that inhibit the immune
system’s attack on the foreign material.
Immune System
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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
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Lymphatic and lymphoid organs
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Deploys lymphocytes
Lymphocytes
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White blood cell that provides main
defense against foreign material
Produced by bone marrow
Organs of the Immune System
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Lymph Nodes
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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
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Connects to lymph nodes and carries fluid called
lymph into the blood stream
Organs of the Immune System
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Lymphocytes
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Form of white blood cells that provide main
defense against foreign matter
Lymphocytes originate from bone
marrow
Organs of the Immune System
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Spleen
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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
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Phagocytes
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Two types:
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Engulf and ingest antigens
Macrophages – attach to tissue and stay
there
Monocytes – circulate in the blood
Nonspecific immune processes
Specific Immune Processes
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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
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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
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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
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T lymphocytes – produced by the
thymus gland and is a slower acting
response.
T cells secrete chemicals that kill
invading organisms. Two types:
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Cytotoxic T (Tc cells)
Helper T (Th cells)
Immune Response
Foreign
material
Cough
Sneeze
Phagocytes
engulf it
Interlukin-1
Th
cells
Gammainterferon
B cells
Interlukin-2
Tc cells
Immune System – Other
organs
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Tonsils
Thymus gland
Why Can’t We Fight Cancer
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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
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Immune function changes during the lifespan,
increasing in childhood and decreasing in old
age.
Unhealthy lifestyles impair immune
functioning
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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
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AIDS
Elephantiasis
Tonsillitis
Mononucleosis
Lymphoma
Diseases of the Immune
System
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Autoimmunity Disorders
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Immune response attacks its own tissue
Arthritis
Multiple sclerosis
Systemic lupus erythematosis
Stress and the Immune
System
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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
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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
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Developing and maintaining healthypromoting 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
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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
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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
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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
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Whether your friends and family
perform the behaviour.
Whether you have social support and
encouragement to perform the
behaviour.
Social Factors in Health
Behaviours
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Social/cultural norms
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Community resources
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Legislation
Social, Personality, and
Emotional Factors
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Support from significant others
Conscientiousness
Stress
Neuroticism
Perception
Cognition
Beliefs
Communication Messages
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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
Attention
100
Optimal
Arousal
50
Raise arousal
0
Reduce arousal
50
Arousal
100
Health Belief Model
Perceived
Pros of action
Perceived
Susceptibility
High
Low
Perceived
threat
High
Perceived
Severity
High
Low
Low
High
Low
Action
Likelihood
High
Perceived
Cons of action
High
Low
Low
Health Belief Model Predicts:
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Preventative dental care
Breast self-examination
Weight management
AIDS risk-related behaviours
Participation in health risk screening
programs
Efficacy Beliefs
Response
Efficacy
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one’s confidence
in the
effectiveness of
reduction
methods
Self Efficacy
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one’s confidence
in using these
methods
Key Factors In Changing
Behaviour
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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
ResponseEfficacy
Value of
Outcome
High
High
Low
Low
Selfefficacy
Subjective
Norms
High
High
Low
Low
Intentions
Behaviour
Change
High
High
Low
Low
Univariate Predictors of Non Adherence to Cancer
Screening
Self-Perceived
Risk Immediate
Post-Counselling
Low
Number (%)
Adherent
Number (%)
Non-adherent
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
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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
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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
Consciousness
raising
Maintenance
Reinforcement
management
Dramatic
relief
Selfre-evaluation
Selfliberation
Helping
relationships
Environmental
re-evaluation
Pros & cons
Trial & error
Counterconditioning
Stimulus control