The Lymphatic System

Lymphatic Vessels

Pick up excess tissue fluid called lymph and return it to the bloodstream.

Lymph

The watery fluid in the lymph vessels collected from the tissue spaces.

Lymph Nodes

A mass of lymphatic tissue that help protect the body by removing foreign material such as bacteria and tumor cells from the lymphatic stream and by producing lymphocytes that function in the immune response

Macrophages

phagocytic cell abundunt in lymphatic and connective tissues; important as an antigen-presenter to T cells and B cells in the immune system.

Lymphoid Organs

they include the spleen, thymus gland, tonsils, lymph nodes, and peyer's patches of the intestine. the common feature is a predominanceof reticular connective tissue and lymphocytes.

Spleen

A blood-rich organ that filters blood of bacteria, viruses, and other debris. It destroys worn-out RBC. It is located in the left side of the abdominal cavity.

Thymus

lymphatic mass found low in the throat overlying the heart. functions during youth. produces thymosin which functions in the programing of certain lymphocytes.

Tonsils

small masses of lymphatic tissue that ring the pharynx. Their job is to trap and remove any bacteria or other foreign pathogens entering the throat

Peyer's Patches

found in the wall of the small intestine. they capture and destroy bacteria, thereby preventing them from penetrating the intestinal wall.

MALT

Acts as sentinel to protect the upper respiratory and digestive tracts from the never-ending attacks of foreign matter entering those cavites.

Nonspecific Defense System

responds immediately to protect the body from all foreign substances, whatever they are. Ex. Skin, mucous membranes.

Specific Defense System

The immune system. It mounts the attack against particular foreign substances.

Immunity

The ability of the body to resist many agents (both living and nonliving) that can cause disease; resistance to disease.

Pathogen

Harmful or disease-causing microorganisms.

Phagocyte

a cell capable of engulfing and digesting particles or cells harmfull to the body much the way and amoeba engulfs food. It engulfs pathogens that make it through the mechanical barriers.

Natural Killer Cells (NK)

A unique group of defensive cells that can lyse and kill cancer cells and virus-infected body cells well before the immune system is enlised in the fight. they "police" the body in blood and lymph.

Inflammatory Response

A nonspecific response that is triggered whenever body tissues are injured.

Pus

the fluid product of inflammation composed of a mixture of dead or dying neutrophils, broken-down tissue cells, and living and dead pathogens.

Complement

A group of at least 20 plasma proteins that normally circulate in inactive forms; when activated by complement fixation, causes lysis of foreign cells and enhances phagocytosis and inflammation.

Interferon

protiens that defend cells that hav not yet been infected.

Fever

abnormallly high body temperature. It is a systemic response to invading microorganisms.

Pyrogens

chemicals secreted by white blood cells and macrophages exposed to foreign cells or substances in the body. They help induce fever.

Immune Response

The immune system's response to a threat. It is antigen specific, systemic, and has "memory

Humoral Immunity

Immunity provided by antibodies present in the body's "humors" or fluids (B cells)

Cellular Immunity

immunitye provided when the lymphocyes( T cells) themselves defend the body

Antigen

Any substance capble of exciting our immune systme and provoking an immune response.

Self-Antigen

Antigens that do not trigger an immune response in us, but they are strongly antigenic to other people.

B Cells

Produce antibodies and oversee humoral immunity

Immunocompetent

The ability of the body's immune cells to recognize (by binding) specific antigens; reflects the presence of plasma membrane-bound receptors.

Plasma Cells

member of a B cell clone; specialized to produce and release antibodies.

Memory Cells

B cell clone members that do not become plasma cells become long-lived memory cells capable of responding to the same antigen at later meetings with it. Provides immunologic memory.

Secondary Responses

second and subsequent responses of the immune system to a previously met antigen; more rapid and more vigorous than the primary response.

Active Immunity

Immunity produced by B cells by the encounter with an antigen, provides immunologic memory. It is either naturally acquired, or artificially acquired.

Vaccines

Help you get artificially aquired immunity

Passive Immunity

short-lived immunity resulting from th introduction of "borrowed antibodies" obtained from an immune animal or human doner; immunological memory is not established.

Antibodies (Igs)

a specialized substance produced by the body that can provide immunity against a specific antigen.

Neutralization

Occurs when antibodies bind to specific sites on bacterial exotoxins or on viruses that can cause cell injury. In this way, they block the harmful effects of the exotoxin or virus.

Agglutination

clumping of (foreign) cells, induced by cross-linking of antigen-antibody compelexes

Precipitation

formation of insoluble complexes that settle out of solution.

Cytotoxic Killer T Cells

effector T cells that directly kills foreign cells, and body cells that have become cancerous.

Helper T Cells

A regulatory T cell that binds with a specific antigen presented by a macrophage; it stimulates the production of other immune cells (killer T cells and B cells) to help fight the invader; acts both directly and indirectly by releasing lymphokins

Suppressor T Cells

Slows or stops the activity of B and T cells once the infection (or attack by foreign cells) has been conquered.

Delayed Hypersensitivity T Cells

effector cells that play a major role in cell-mediated allergies and long-term, or chronic, inflammations.

Memory T Cells

T cells that remain alive to provide the immunological memory for each antigen encountered and enable the body to respond quickly to its subsequent invasions.

Allergies

abnormally vigorous immune responses in which the immune system causes tissue damage as it fights off a perceived "threat" that would otherwise be harmless to the body.

Allergen

It causes allergic response. it is distinguished from antigens producing essentially normal responses

Immunodeficiencies

include both congenital and acquired conditions in which the production or function of immune cells or complement is abnormal.

Autoimmune Disease

The production of antibodies or effector T cells that attack a person's own tissue.