CH.13: BODY DEFENSE MECHANISMS

Swelling

-Histamine causes capillaries to become leaky, and fluid seeps into tissues -Fluid brings clotting factors, oxygen, and nutrients

Steps of Adaptive Immune Response

-Threat: Foreign organism or molecule (an antigen) enters the body -Detection: Macrophage detects foreign organism or molecule and engulfs it -Alert:Macrophages present antigens to helper T cells. Macrophages are antigen-presenting cells. Helper T cells are the main switch for the adaptive immune response -Alarm: Helper T cells activate appropriate B cells and T cells to destroy the specific antigen. When activated, these cells divide to form clones of cells designed to eliminate the specific antigen from the body. Clonal selection is critical to the adaptive immune response -Building specific defenses: B cells form plasma cells that secrete antibodies into the bloodstream, which bind to antigens. T cells form cytotoxic T cells that attack. Process by which immune cells increase in number is termed clonal selection -Defense: the antibody-mediated response. Antibodies secreted by plasma cells are specific to the antigen and eliminate that antigen. Precipitation, Lysis (bursting), Attraction of phagocytes, Neutralization. An effector cytotoxic T cell releases perforins, which cause holes to form in cells with the particular antigen

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. Long lived because memory cells are produced.

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 fluids, 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 other pathogens and cancer cells.

Continued Surveillance

Immunological memory allows for a more rapid response on subsequent exposure to the antigen -Primary response: Occurs during body's first encounter with a particular antigen•Antibody concentration rises slowly -Secondary response: Occurs during subsequent encounter with that antigen. Strong and swift due to the large number of memory cells programmed to respond to that particular antigen

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'

Cancer Cells

Once-normal body cells whose genetic changes cause unregulated cell division

What are the 3 lines of defense?

Physical and chemical surface barriers, internal cellular and chemical defenses, and immune response.

First line of defense

Physical barriers: skin & mucous membrane; Chemical barriers: Sweat and oil, lining of the stomach, urine, saliva, and tears.

Phagocyte

Scavenger cells specialized to engulf and destroy particulate matter, such as pathogens, damaged tissues, or dead cells.

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.

Histamine

Substance released by basophils and mast cells during an inflammatory response that causes blood vessels to dilate and become more permeable.

T Lymphocyte

T cell. Type of WBC. Some T lymphocytes attack and destroy cells that are not recognized as belonging to the body, such as an infected cell or a cancerous cell.

Passive Immunity

Temporary immune resistance that develops when a person receives antibodies that were produced by another person or animal. Short lived because the recipients body was not stimulated to produce memory cells.

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 lymphocyte surface, an antigen selectively activates only those lymphocytes able 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 system response by presenting the antigen to B cells and secreting chemicals that stimulate other cells of the immune system. It is also known as the T4 cell or the CD4 cell, after the receptors on its surface.

Interferon

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 NK cells, which kill the virus infected cell.

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 invaders in a variety of 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, initiating an immune response toward that antigen. An important type of antigen-presenting cell is a macrophage.

Pathogen

A disease-causing organism.

Complement System

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

Monoclonal Antibodies

A group of identical antibodies that bind to one specific antigen -Used in research, clinical diagnosis, and disease treatment -Used in home pregnancy tests, for example

Macrophage

A large phagocytic cell derived from a monocyte that lives in loose connective tissue and engulfs anything detected as foreign.

Memory Cell

A lymphocyte (B or T cell) of the immune system that forms in response to an 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. 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.

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 & T cells.

Natural Killer (NK) cells

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

Perforins

A type of protein released by a NK cell that creates numerous pores 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.

Third line of defense

Adaptive immune system: Has specific responses and memory -Organs of the lymphatic system are important components -Defined by its function: recognize and destroy specific pathogens or foreign molecules -The body's specific defenses -Important characteristics -Specificity: directed at a specific pathogen -Memory: remembers the pathogen and attacks it so quickly that illness does not result upon second exposure

Fever

An abnormally high body temperature: -Caused by pyrogens: chemicals that reset the brain's thermostat to a higher temperature -A mild or moderate fever helps fight bacterial infection -A very high fever (over 105ºF or 40.6ºC) is dangerous

Autoimmune Disorders

An immune response misdirected against the body's own tissues. -Organ specific: Usually caused by problematic T cells. Examples: Hashimoto's thyroiditis, Type I diabetes -Non-Organ specific: Usually caused by problematic B cells. Example: systemic lupus erythematosus.

Immunoglobulin

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

B Lymphocyte

B cell. Type of WBC important in antibody-mediated immune responses that can transform into a plasma cell and produce antibodies.

Redness

Blood flow to the area increases, delivering defensive cells and removing dead cells and toxins. Mast cells release histamine, which causes blood vessels to dilate

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 traits arise through natural selection.

Pain

Can be caused by: -Excess fluid -Bacterial toxins -Prostaglandins

PLAN

Defense process: Precipitation, Lysis, Attraction of phagocytes, Neutralization.

Second line of dense

Defensive cells: Phagocytes- neutrophils, macrophages, and eosinophils, & NK cells. Defensive proteins: Interferons and the complement system. Inflammatory response: redness, heat, swelling, fever, and pain.

Monoclonal Antibody

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

Pathogens

Disease-causing bacteria, viruses, prions, protozoans, fungi, parasitic worms

Steps of an Allergic Reaction

During the first exposure: Allergens cause plasma cells to release class IgE antibodies -IgE antibodies bind to mast cells or basophils On subsequent exposures: Allergen combines with IgE attached to mast cells and causes release of histamine. Histamine causes redness, swelling, itching, and other symptoms of an allergic response

Heat

•Body temperature rises as a result of increased blood flow •Speeds healing and activities of defensive cells