The Immune System

1. The Immune System • Mariela & Julia

2. Basic Immune Vocab • Leukocyte: white blood cell • Lymphocyte: white blood cell with a large spherical nucleus surrounded by a smooth cytoplasm. • Pathogen: invading microorganisms and viruses (eg-cold/flu) • Antigen: foreign molecules that stimulate a response from the immune system (eg-allergies to pollen) • Antibodies: defend against infection in body fluids • Cytokines: cell signaling protein molecules

3. Red blood cell, platelet, and white blood cell.

4. Innate and Acquired Immunity • Innate immunity: involves recognition of traits shared by a broad range of pathogens using a set of receptors, and results in a rapid response. • Barrier defenses (skin, mucous membranes secretions) • Internal defenses: phagocytic cells, ain't microbial proteins, inflammatory response, natural killer cells • Acquired immunity: recognizes traits specific to particular pathogens using receptors, resulting in a slower response. • Humoral response: antibodies defend against infects in body fluids • Cell-mediated response: cytotoxic lymphocytes defend against infection in body cells

5. Try THIS!!! • Although pus is often seen simply as a sign of a infection, it also an indicator of immune defenses in action! Explain.

6. Phagocytosis Chap 43 Campbell!

7. Innate Immunity • Phagocytic white blood cells • Neutrophils: ingest/destroy microbes via phagocytosis • Monocytes: go into tissues and develop into phagocytic cells. • Eosinophils: defend against parasites by secreting hydrolytic enzymes. • Antimicrobial Proteins • Interferon: provide innate defense by making cells produce substances to inhibit viral infection • Inflammatory Response • Triggered by injury to tissue. Histamines are released to trigger the dilation of the capillaries, which allows clotting agents. • Natural Killer Cells (NK cells) • Recognize and remove diseased cells.

8. Acquired Immunity • All vertebrates have two types of white blood cells (lymphocytes)!! • B lymphocytes (B cells): reproduce in the bone marrow • T lymphocytes (T cells): reproduce in the thymus (butterfly shaped gland at the base of your neck) • B or T cell activation occurs when an antigen binds to the B or T cell. • Clonal selection: B cell activation is enhanced by cytokines, allowing the lymphocyte to form two clones, thus creating a multitude of cells specific to fighting the particular antigen. • Effector cells fight the antigen. • Memory cells live longer and bear receptors for the same antigen, allowing the body to fit it successfully the next time. Pollen (possible antigen)

9. B & T cells • B cell receptors bind to intact antigens. • T cell receptors bind to antigens on antigen presenting cells (AHCs) on their major histocompatibilty complex molecules (MHCs). • MHCs: proteins that are the product of gene groups. Class I MHCs are on all body cells except for red blood cells. Class II MHCs are made by B cells, macrophages, and dendritic (branching neuron) cells. • Each B or T cell responds to only one antigen. • Primary immune response (the pilot episode): body exposed to antigen, lymphocyte activated. • Secondary immune response (season two): same antigen is encountered again!!! It is faster and stronger!!!

10. TRY THIS!!! • Explain the two advantages of having memory cells when a pathogen is encountered for a second time!