IMMUNITY Susceptibility: Lack of resistance to a disease. Effected by: General health Nutrition Age Stress Resistance: Ability to ward off disease. ________________________________________resistance : Generally present Defenses against any pathogen (not directed toward any particular pathogen) Specific resistance: Immunity, resistance to a specific pathogen. INNATE RESISTANCE/IMMUNITY Species: Pathogens may only infect a limited range of species. e.g. Mumps: Infects humans not dogs or cats. Anthrax: Cattle and humans but not birds. Reasons for species resistance (Many unknown) Physiology: e.g. Anthrax: _________________________________________ is the key! Humans: 37oC Birds: 41-45oC Pasteur exposed chickens to anthrax and then lowered their body temperature. The chickens died of anthrax. b. Anatomy: e.g. Plant diseases (Certain chemical receptors plant pathogens require do not exist in/on the human body.) c. Behavior/Diet: e.g. Fish tapeworm Diphyllobotrium latum. Ingested in raw fish. Any species that doesn’t eat fish is unlikely to get this disease. 2) Race or Strain e.g. Caucasians are more susceptible to diphtheria, influenza, and gonorrhea. Blacks and American Indians are more susceptible to TB. 3) ___________________________________________: Hormone levels effect the immune system. Mechanical/Physical Barriers 1)Intact skin: Epidermis consists of tightly packed cells with Keratin, a protective protein. Acts as a barrier to most microbes. 2) Mucous membranes: Line body cavities that open to the exterior. e.g. Digestive, respiratory, urinary, and reproductive tracts. The epithelial layer of mucus membranes secretes mucus which acts as a trap and physical barrier. Much less protective than skin. 3) Hairs of the Ears and Nose: Filter and trap microbes. 4) Ciliary/Mucociliary escalator: Microbes trapped in mucus are transported away from the lungs. 5) __________________________________________apparatus: Manufactures and drains away tears. Continual washing of the eyes. 6) Salivary glands: Wash microbes from teeth and mucus membranes of the mouth. 7) Urine: Flow of urine moves microorganism out of the urinary tract. 8) Vaginal secretions: Help remove microorganism from of the vagina. 9) Reflexes: Coughing Sneezing Vomiting Diarrhea CHEMICAL DEFENSES Sebaceous Glands: Secrete sebum: contains fatty acids: gives the skin a low pH (3-5) Sweat Glands: Produce perspiration contains: NaCl and lysozyme Gastric Juice: Contains HCl low pH (1.2-3.0) Transferrins: Iron-binding proteins in the blood. Limits available iron needed for microbial growth. Blood: The Fluid Portion Plasma and Serum Formed Elements Erythrocytes (RBCs) Leukocytes (WBCs) Thrombocytes/Platelets Leukocytes (WBCs) Granulocytes: Have granules in the cytoplasm and a lobed nucleus. 1) Neutrophiles (PMNs) 2) Basophils 3) Eosinophiles __________________________________________ 2 Types 1) Monocytes/Macrophages 2) Lymphocytes Differential Blood Count Determines the relative percent of each WBC type. Many infections cause an increase or decrease in WBC numbers. Leukocytosis: Increase in total WBC count. _____________________________________________: Decrease in WBC count. Neutrophilia: Increase Neutrophile count. >10% Bands = Infection or inflammation. Neutropenia: Decrease in Neutrophil count. Eosinophilia: Increased Eosinophil count. e.g. Allergies and Parasitic infections Lymphocytosis: Increased Lymphocyte count. Functions of WBCs Neutrophils: __________________________________________ Basophils/Mast Cells: Produce histamine Eosinophils: Toxic to parasites, some phagocytosis Monocytes: Phagocytic as mature macrophages Lymphocytes: Involved in specific immunity Mononuclear Phagocytic/ Reticuloendothelial System (RES) Consists of phagocytes which enter certain tissues and remain there: Fixed Macrophages/Histocytes: Ingest bacteria and debris as they flow past. Found in the Liver: Kupffer cells Lungs: _________________________________________________ Macrophages Nervous system: Microglial cells Skin: Langerhan’s cells Also located in Spleen, Lymph nodes, bone marrow and peritoneal cavity. Other macrophages are called wandering macrophages. PHAGOCYTOSIS INFLAMMATORY RESPONSE Response to tissue damage by a combination of nonspecific defenses. Characterized by: Redness (Rubor), Pain(Dolor), Heat (Calor), Swelling (Tumor/Edema) Functions of Inflammation 1)Destroy the injurious agent, and remove it. 2) Confining or walling off the injurious agent and it’s by products. 3) To repair or replace damaged tissues. In response to injury _____________________________________proteins (complement, cytokine, fibrinogen and kinins) are activated and their concentration increases. _____________________________________________ Injured tissues release: Histamine, Kinins, Prostaglandins, Leukotrienes These substances dilate (increase the diameter) of blood vessels Redness and Heat Increased permeability: Margination and emigration/diapedesis of WBCs Increased WBCs at site of injury PMNs reach site first (Short lived) Monocytes reach site within 24hr. (Longer lived) _______________________________________________: Increased flow of fluids from blood to tissue spaces. Tissue Repair: The final stage of inflammation. Begins during the active phase of inflammation. Fever (Systemic increase in body temperature) Endogenous Pyrogens (Interlukin 1) IL-1 and alpha tumor necrosis factor. Secreted by WBCs (Monocytes & Macrophages) Act on the hypothalamus (Body's thermostat) Hypothalamus releases prostaglandins. Increase in body temperature. Inhibits the growth of some organisms. Speeds up body's chemical reactions. Decreases available iron. When IL-1 is eliminated, body temperature falls. (Crisis) ____________________________________________________System A group of over 30 proteins found in the blood. Complements antigen antibody reactions. Binds to immune complexes. Several functions: Cell lysis: Membrane attack complex WBC chemotaxis: Attracts phagocytes Opsonization or immune adherence: enhanced phagocytosis Inflammation. Interferons (IFNs) Alpha IFN & Beta IFN: Cause cells to produce antiviral proteins that inhibit viral replication Gamma IFN: Increases the activity of neutrophils and macrophages in phagocytizing bacteria.
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