The Immune System Mariela & Julia

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

Red blood cell, platelet, and white blood cell.

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

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

Phagocytosis Chap 43 Campbell!

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.

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)

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!!!

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