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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)

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The immune system
The Immune System

  • Mariela & Julia

Basic immune vocab
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

Innate and acquired immunity
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
Try THIS!!!

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


Chap 43


Innate immunity
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
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 & 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 this1

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