lecture immune function and behavious

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 White blood cell that provides main defense against foreign material Produced by bone marrow  Lymphocytes   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. Connects to lymph nodes and carries fluid called lymph into the blood stream  Lymph vessels  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 Macrophages – attach to tissue and stay there Monocytes – circulate in the blood  Two types:    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 material Cough Sneeze Phagocytes engulf it Interlukin-1 Th cells Gammainterferon B cells Interlukin-2 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 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      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 Attention Optimal Arousal 50 Raise arousal Reduce arousal 0 50 Arousal 100 Health Belief Model Perceived Susceptibility High Low Perceived Severity Perceived Pros of action Perceived threat High High Low Perceived Cons of action High Low Action Likelihood High Low 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 Beliefs Response Efficacy  Self Efficacy  one’s confidence in the effectiveness of reduction methods 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 Behaviour Ajzen & Fishbein, 1986 ResponseEfficacy High Low Selfefficacy Value of Outcome High Low Intentions High Behaviour Change High Subjective Norms High Low Low Low High Low Univariate Predictors of Non Adherence to Cancer Screening Self-Perceived Risk Immediate Post-Counselling Low Medium High X2 (2) = 7.79, p < 0.02 Number (%) Adherent 18 (72.0%) 28 (71.8%) 7 (36.8%) Number (%) Non-adherent 7 (28.0%) 11 (28.2%) 12 (63.2%) 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 raising Dramatic relief Environmental re-evaluation Reinforcement management Selfre-evaluation Pros & cons Selfliberation Trial & error Helping relationships Counterconditioning Stimulus control