Immune System Ch 43 Immune Response in Animals

Immune System Ch. 43

Immune Response in Animals Divided into 2 Categories 1. Innate immunity – present before any exposure to pathogens – effective from the time of birth – involves nonspecific responses to pathogens – consists of external barriers plus internal cellular and chemical defenses

Immune Response in Animals Divided into 2 Categories 2. Acquired immunity (adaptive immunity) – develops after exposure to agents (microbes, toxins, or other foreign substances) – activated after innate immune defense – involves a very specific response to pathogens

Fig. 43 -2 Pathogens (microorganisms and viruses) INNATE IMMUNITY • Recognition of traits shared by broad ranges of pathogens, using a small set of receptors • Rapid response ACQUIRED IMMUNITY • Recognition of traits specific to particular pathogens, using a vast array of receptors • Slower response Barrier defenses: Skin Mucous membranes Secretions Internal defenses: Phagocytic cells Antimicrobial proteins Inflammatory response Natural killer cells Humoral response: Antibodies defend against infection in body fluids. Cell-mediated response: Cytotoxic lymphocytes defend against infection in body cells.

Innate Defense Mechanisms 1. Barrier Defenses (1 st Line of Defense) – Skin – Mucous membranes produce mucus • Traps microbes – Cilia in respiratory system • Sweeps mucus with microbes out of lungs – Body secretions = hostile environment • Lysozymes • Acid in stomach • Oil and sweat give skin acidic p. H

Innate Defense Mechanisms 2. Cellular Innate Defenses (2 nd Line of Defense) • Phagocytic Cells – Neutrophils engulf and destroy microbes – Macrophages are part of the lymphatic system and are found throughout the body – Eosinophils discharge destructive enzymes – Dendritic cells stimulate development of acquired immunity

Neutrophils • Most abundant phagocytic cells in mammals • http: //biologyanimations. blogspot. com/search/label/neutrop hill

Macrophages • http: //www. youtube. com/watch? v=Jg 8 Dob 35 Rp 4

Innate Defense Mechanisms 2. Cellular Innate Defenses (2 nd Line of Defense) • Inflammatory Response – Following an injury, mast cells release histamine, which promotes changes in blood vessels – These changes increase local blood supply and allow more phagocytes and antimicrobial proteins to enter tissues – Pus, a fluid rich in white blood cells, dead microbes, and cell debris, accumulates at the site of inflammation

Inflammatory Response • http: //wps. aw. com/bc_goodenough_boh_3/1 04/26720/6840553. cw/content/index. html

– Inflammation can be either local or systemic (throughout the body) – Fever is a systemic inflammatory response triggered by pyrogens released by macrophages, and toxins from pathogens – Septic shock is a life-threatening condition caused by an overwhelming inflammatory response

Fig. 43 -8 -3 Pathogen Mast cell Splinter Chemical Macrophage signals Capillary Red blood cells Phagocytic cell Fluid Phagocytosis

Innate Defense Mechanisms 2. Cellular Innate Defenses (2 nd Line of Defense) – Complement – proteins that lead to lysis of invading cells – Interferon blocks against cell-to-cell viral infections – Natural killer cells destroy virus-infected body cells and cancerous cells (lyse cell membranes)

Complement • http: //highered. mcgrawhill. com/sites/0072556781/student_view 0/ch apter 31/animation_quiz_1. html

Interferon • Proteins that cause innate defense against viral infections. • http: //highered. mcgrawhill. com/sites/0072556781/student_view 0/ch apter 31/animation_quiz_2. html

Acquired Immunity Mechanisms • White blood cells called lymphocytes recognize and respond to specific antigens • An antigen is any foreign molecule to which a lymphocyte responds – T cells mature in the thymus above the heart – B cells mature in bone marrow • Both travel in the blood, lymphatic system • Each is specialized to recognize a specific type of molecule • A single B cell or T cell has about 100, 000 identical antigen receptors

Acquired Immunity Mechanisms Involves 3 Phases: 1. Recognition – Antigen receptors on B and T cells recognize epitopes (antigens) by binding to them • Antigens = any substance that causes a B or T cell immune response • Epitopes = accessible piece of an antigen

Antigens (Epitopes) • http: //highered. mcgrawhill. com/sites/0072943696/student_view 0/ch apter 14/animation__antigenic_determinants_ _epitopes_. html

Acquired Immunity Mechanisms Involves 3 Phases: 2. Activation Phase – B and T cells are activated by the binding of the antigen receptor – B and T cells undergo rapid cell division – They form • • Effector cells Memory cells

Acquired Immunity Mechanisms Involves 3 Phases: 3. Effector Phase – B cells produce humoral response – produce antibodies – T cells are involved in cell-mediated response • http: //highered. mcgrawhill. com/sites/0072507470/student_view 0/c hapter 22/animation__the_immune_respons e. html

Review of Video • Antigenic Molecules bind to specific B and T Lymphocytes – Lymphocyte becomes active and proliferates – It differentiates into plasma cell and memory cells • Primary Immune Response – Plasma cells fight antigen immediately 7 -10 days • Secondary Immune Response – Memory cells bear the same antigen and circulate for lifetime – Immunological memory

T Helper Cells • http: //highered. mcgrawhill. com/sites/0072507470/student_view 0/ch apter 22/animation__tcell_dependent_antigens__quiz_2_. html

Major Histocompatibility Complex • Cell surface markers that bring the antigen to the cell surface so that T cells are activated • No 2 people have same MHC except identical twins • 2 types – Class I MHC • Found on almost every cell – Class II MHC • Found on specialized cells: macrophages, B cells, activated T cells

Allergies • http: //highered. mcgrawhill. com/sites/0072556781/student_view 0/ch apter 33/animation_quiz_2. html

AIDS • http: //highered. mcgrawhill. com/sites/0072495855/student_view 0/ch apter 24/animation__how_the_hiv_infection_ cycle_works. html