Ch. 13: Body Defense Mechanisms

active immunity

Immune resistance in which the body actively participates by producing memory B cells and memory T cells after exposure to an antigen, either naturally or through vaccination.

Antibody-mediated immune response

Immune system responses conducted by B cells that produce antibodies and that defend primarily against enemies that are free in body fluid, including toxins or extracellular pathogens, such as bacteria or free viruses.

Cell-mediated immune response

Immune system responses conducted by T cells that protect against cellular threats, including body cells that have become infected with viruses or others pathogens and cancer cells.

Macrophage

Large white blood cell that removes bacteria, foreign particles, and dead cells

Effector cell

Lymphocytes that are responsible for the attack on cells or substances not recognized as belonging in the body.

MHC Marker

Molecules on the surface of body cells that label the cell as "self".

A cytotoxic T cell could attack all of the following except: a. transplants of foreign tissue. b. cells infected with viruses. c. cancerous cells. d. viruses that are free in the bloodstream.

viruses that are free in the bloodstream.

When the say they are looking for a suitable donor for a kidney transplant, they are looking for someone _____________.

whose tissues have self makers similar to those of the recipient.

Mast Cell

Small, mobile connective tissue cells often found near blood vessels. In response to injury, mast cells release histamine, which dilates blood vessels and increases blood flow to an area, and heparin, which prevents blood clotting.

T lymphocyte

T cell. A type of white blood cell. Some T lymphocytes attack and destroy cells that are not recognized as belonging in the body, such as an infected cell or a cancerous cell.

plasma cell

The effector cell, produced from a B lymphocyte, that secretes antibodies.

Clonal selection

The hypothesis that, by binding to a receptor on a lymphocytes surface, and antigen selectively activates only those lymphocytes are to recognize that antigen and programs that lymphocyte to divide, forming an army of cells specialized to attack the stimulating antigen.

Helper T cell

The kind of T lymphocyte that serves as the main switch for the entire immune response by presenting the antigen to B cells and by secreting chemicals that stimulate other cells of the immune system. It is also known as a T4 cell or a CD4 cell, after the receptors on its surface.

In clonal selection of B cells, which substance is responsible for determining which cells will eventually become cloned?

antigen

B lymphocyte

b cell. A type of white blood cell important to antibody-mediated immune responses that can transform into a plasma cell and produce antibodies.

Which of the following pairing of cell type and function is incorrect? a. helper T cell -serves as "main switch" that activates both the cell-mediated immune responses and the antibody-mediated immune responses. b. cytotoxic T cell- present antigen to the helper T cell. c. macrophage-roam the body looking for invaders, which are engulfed and digested when they are found. d. suppressor T cell- shuts off the immune response when the invader has been removed.

cytotoxic T cell- present antigen to the helper T cell.

_________________ is a chemical released by mast cells and basophils that produces most of the symptoms of an allergy.

histamine

The piece of the antigen displayed on the surface of a macrophage __________.

informs the other cells in the immune system of the exact nature of the antigen they should be looking for (what the antigen "looks like").

The lymphocytes that develop and mature in the bone marrow are the _____________.

macrophages

________________ are important antigen-presenting cells.

macrophages (dendritic cells, B cells)

A cell that kills any unrecognized cell in the body and is part of the nonspecific body defenses is a(n) _________.

natural killer cells

Innate immune system defenses include which of the following? a. B cells b. T cells c. plasma cells d. phagocytosis

phagocytosis

Antibodies are produced by _________.

plasma cells

Which of the following is not a function of the inflammatory response? a. preventing the injurious agent from spreading to nearby tissue. b. replacing injured tissues with connective tissue. c. disposing of cellular debris and pathogens. d. setting the stage for repair processes.

replacing injured tissues with connective tissue.

Fever ___ ______________ _ _________________

results from the actions of chemicals that reset the body's thermostat to a higher setting.

antibody

A Y-shaped protein produced by plasma cells during an adaptive immune response that recognizes and binds to a specific antigen because of the shape of the molecule. Antibodies defend against invader in a variety ways, including neutralization, agglutination and precipitation, or activation of the complement system.

Antigen-presenting cell (APC)

A cell that presents an antigen to a helper T cell, initialing an immune response toward that antigen. An important types of antigen of antigen-presenting cells is a macrophage.

Complement System

A group of about 20 proteins that enhances the body's defense mechanisms. The complement system destroys cellular pathogens by creating holes in the plasma membrane, making the cell leaky, enhancing phagocytosis, and stimulating inflammation.

What is an antigen?

A large molecule on the surface of an invader that triggers an immune response.

Memory cell

A lymphocyte (B cell or T cell) of the immune system that forms in response to antigen and that circulates for a long period of time; such cells are able to mount a quick immune response to a subsequent exposure to the same antigen.

Inflammatory Response

A nonspecific body response to injury or invasion by foreign organisms. It is characterized by redness, swelling, heat, and pain.

Allergy

A strong immune response to an antigen (an allergen) that is not usually harmful to the body.

Histamine

A substance released by basophils and mast cells during an inflammatory response that causes blood vessels to widen (dilate) and become more permeable.

Antigen

A substance that is recognized as foreign by the immune system. Antigens trigger an immune response.

Cytotoxic T cell

A type of T lymphocyte that directly attacks infected body cells and tumor cells by releasing chemicals called perforins that cause the target cells to burst.

suppressor T cells

A type of T lymphocyte that turns off the immune response when the level of antigen falls by releasing chemicals that dampen the activity of both B cells and T cells.

Natural killer

A type of cell in the immune system. These cells, probably lymphocytes, roam the body in search of abnormal cells and quickly kill them.

Interferon

A type of defensive protein produced by T lymphocytes that slows the spread of viruses already in the body by interfering with viral replication. Interferons, also attract macrophages and natural killer cells, which kill the virus-infected cell.

perforins

A type of protein released by a natural killer cell that creates numerous pores (holes) in the target cell, making it leaky. Fluid is then drawn into the leaky cell because of the high salt concentration within, and the cell bursts.

Phagocyte

A white blood cell that destroys pathogens by engulfing them and breaking them down

Indicate the correct statement: a. An antibody is specific to one particular antigen. b. Antibodies are held within the cell that produces them. c. Antibodies are produced by macrophages. d. Antibodies can be effective against viruses that are inside the host cell.

An antibody is specific to one particular antigen.

Autoimmune disorders

An immune response misdirected against the body's own tissues.

passive immunity

temporary immune resistance that develops when a person receives antibodies that were produced by another person or animal.

immunoglobulin

Any of the five classes of proteins that constitute the antibodies.

Adaptive Immune Response

Body defense responses that are acquired by exposure to cells or substances that do not belong in the body. Antibody-mediated responses and cell-mediated responses are involved. Adaptive responses have memory for the pathogen that triggered them.

monoclonal antibody

Defensive proteins specific for a particular antigen secreted by a clone of genetically identical cells descended from a single cell.