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THE PEARLS OF WISDOM FROM EPI 201. BY: MILANA BERNASEK RN. Objectives:. Know at least three components of the immune system Describe at least two cells in the immune system and how they respond to infectious agents Identify factors that influence the immune response to infectious agents.
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THE PEARLS OF WISDOM FROM EPI 201 BY: MILANA BERNASEK RN
Objectives: • Know at least three components of the immune system • Describe at least two cells in the immune system and how they respond to infectious agents • Identify factors that influence the immune response to infectious agents
Organs of the immune system • The spleen-A staging ground and place where immune system cells confront foreign microbes. • The Lymphatic System-(1)Lymphatic vessels form a circulatory system that operated in close partnership with blood circulation. (2) carries lymph, a fluid that contains WBC’s (chiefly lymphocytes). And (3) lymph nodes provide “meeting grounds”.
CELLS OF THE IMMUNE SYSTEM • Arise in bone marrow • Myeloid progenitor cells develop into cells that respond early and nonspecifically to infection • Lymphoid progenitor cells develop into lymphocytes
Lymphocytes • Mononuclear WBC’s produced in bone marrow • Two major classes: B cells (mature in bone marrow, produce antibodies and part of antibody-mediated immunity. T cells(mature in Thymus, coordinate entire immune response and eliminate viruses hiding in infected cells, Attack and destroy, Responsible for cell mediated (cellular) immunity.
ANTIGEN: • Substance, molecule, or agent (such as bacterium or virus) that triggers an immune response • Recognized by immune system as foreign
ANTIBODIES: • Produced to target a specific antigen • When they combine with antigens, can activate a cascade of proteins (complement) • Complement works with antibodies to destroy foreign invaders
COMPONENTS OF THE IMMUNE SYSTEM • Physical/mechanical barriers • Innate immune system • Adaptive (acquired) immune system
PHYSICAL/MECHANICAL BARRIERS • Skin-first line defense • Flushing-tears, saliva, micturation, peristalsis • Acid contents of stomach; bile salts • Cilia action of lung and cough reflex • Mucous membranes • Inflammatory response and phagocytosis (see the video of phagocyte engulfing Aspergillus & Candid conidia: http://en.wikipedia.org/wiki/file:s1-Polymorphonuclearcellswithconidiainliquidmedia.ogg. • Fever
Physical/mechanical cont: inflammatory response • Vascular phase • Cellular phase • Healing phase
Fever: • Mechanical response • Pathogenic organisms survive best at normal body temperature • Immune system can kill pathogens by slightly raising body’s temperature • Negative aspect • Release of cytokines that produce harmful effects
Non-specific Immune Response Cellular barriers • Leukocytes involved • Do not confer long lasting immunity • Identify and eliminate pathogens Complement • Complex linear protein molecule • Called an “effector” molecule
Non-specific cont: • Leukocytes (WBC’s) • Neutrophils • Phagocytes • Basophiles • Eosinophils
Specific (adaptive or Acquired) Immunity • Humoral • Cell mediated • Lymphocytes involved • Two types
Mechanism of antibody Production • Macrophage attracted to/ingests foreign antigen • Antigenic proteins cleaved: fragments appear on surface of macrophage • T cell sees macrophage with antigenic protein on surface and stimulates B cell • Stimulated B cell divides and makes plasma cells; plasma cells make antibodies Note: takes approx. 3 weeks after exposure for detectable antibodies to appear in the blood
Types of Antibodies • IgM-current disease; first at site of initial exposure • IgG-first with subsequent exposure • IgA-secreted on mucous membranes • IgE-allergic reactions • IgD-short-lived; cord blood • Note: A mnemonic to remember: • IgM=I’ve got it and I’m making it • IgG=I got it and it’s Gone
Immune Suppression can be caused by….. • Genetic deficiencies • Drugs • Cancer • Viral infections • Malnutrition • Stress • Iatrogenic factors
Summary • The immune system is a complex network of cells, tissues and organs that work together to defend the body against attacks by “foreign” invaders • When the immune system hits the wrong target or is crippled, it can unleash a torrent of diseases, including allergy, arthritis and AIDS
References: • EPI 201 • Craig CG. Microbial Pathogenicity and Host Response In: Chapter 14, APIC text of Infection Control and Epidemiology, 3rd ed. • http://www.cancer.gov/cancertopics/understandingcancer/immunesystem (National Cancer Institute. The Immune System • http://www.nlaid.nih.gov/topics/immunesystem/pages/default.aspx (National Institute of Allergy and Infectious diseases. The Immune System)