Bold Word chapter 20

Immunity

the ability to defend the body against infection, illness and disease

Lymphocytes

specific types of leukocytes (wbc) that play a role in the immune response. They are small cells with a single large nucleus. Types include t-cells, b-cells and natural killer cells.

Immunity

the ability to defend the body against infection, illness and disease

Lymphocytes

specific types of leukocytes (wbc) that play a role in the immune response. They are small cells with a single large nucleus. Types include t-cells, b-cells and natural killer cells.

Lymphatic vessels

the vessels of the lymphatic system. Also called 'lymphatics.'

Primary lymphoid organs

include sites where lymphocytes are formed and mature (Red bone marrow and thymus.)

Secondary lymphoid organs

sites where lymphocytes are activated and cloned (production of identical copies.) These structures include lymph nodes, tonsils, MALT (mucosa associated lymphatic tissue), appendix and spleen.

Lymph

fluid carried in the lymphatic vessels. This is fluid that has leaked out of the vessels of the cardiovascular system and will be returned to the venous system by the lymphatic vessels.

Larger lymphatic vessels

have valves which keep the fluid moving in one direction toward the heart.

Lacteals

a terminal lymphatic vessels within an intestinal villus. Their job is to transport lipids absorbed by the digestive tract.

Thoracic duct

collects lymph from the body inferior to the diaphragm and from the left side of the body superior to the diaphragm.

Right lymphatic duct

collects lymph from the right side of the body superior to the diaphragm.

Allograft

Most common type of graft. Involves transplant of tissues between non-identical individuals of the same species.

Autograft

Graft that involves the transplant of tissues from one site to another on the same individual.

Xenograft

Grafts that involve the transplant of tissues from a different species.

Isografts

grafts that involve the transplant of tissues from genetically identical individuals.

Lymphedema

a condition in which interstitial fluids accumulate and the affected area gradually becomes swollen and grossly distended.

Elephantiasis tropica

a condition caused by filarial worms in which lymphatic fluid accumulates causing severe swelling in the extremities.

Antigens

a substance capable of inducing the production of antibodies.

T cells

lymphocytes responsible for cell-mediated immunity and for the coordination and regulation of the immune response; includes regulatory T cells (helper and suppressors) and cytotoxic (killer) T cells. There are also memory T cells.

B cells

lymphocytes capable of differentiating into plasma cells, which produce antibodies. There are also memory B cells.

Natural Killer Cells

a type of lymphocyte that is responsible for immune surveillance. They are part of the innate immunity.

Macrophages

A phagocyte that ingests damaged cells, bacteria, and cellular debris.

Dendritic cells

A class of leukocytes that often function as antigen-presenting cells and are located in places such as the epidermis of the skin.

Appendix

A blind, worm-like sac off the initial portion of the large intestine that contains lymphatic tissue.

Lymphopoiesis

lymphocyte production. It involves the red bone marrow, thymus, and peripheral lymphoid tissues.

Thymus

a lymphoid organ, the site of T cell maturation.

Red bone marrow

in adults, it is primarily found in the flat bones such as the pelvic girdle, sternum, hip bones, skull, ribs, and shoulder blades. It is also found at the proximal ends of the long bones of the femur and humerus. Red blood cells, white blood cells and platelets are produced in the red bone marrow.

Cytotoxic T cells

a type of lymphocyte that attack foreign cells or body cells infected by viruses. They are also known as killer T cells.

Helper T cells

A type of lymphocyte that stimulate the activation and function of both T cells and B cells.

Memory T cells

There are both memory helper T cells and memory cytotoxic T cells that remain in the case of a second encounter with the pathogen.

Suppressor T cells

Inhibit the activation and function of both T cells and B cells.

Plasma B cells

Produce and secrete antibodies. Responsible for antibody mediated (or humoral) immunity.

Memory B cells

Remain in the body in case of a second encounter with the pathogen.

NK cells

Lymphocytes that attack foreign cells, body cells infected with viruses, and cancer cells that appear in normal tissues. They are responsible for immune surveillance and are part of the non-specific immune system.

MALT

Mucosa-associated lymphoid tissue. This is a diffuse system of small concentrations of lymphoid tissue found in various sub-mucosa membrane sites of the body.

Tonsils

Lymphoid tissue in the walls of the pharynx.

Pharyngeal tonsil

Adenoid (located in the nasopharynx).

Lingual tonsils

Found at the base of the tongue.

Palantine tonsils

Located at the posterior, inferior margin of the oral cavity along the boundary of the pharynx.

Tonsillitis

An inflammation of the tonsils (especially the palantines).

Lymph nodes

Small lymphoid organs ranging in diameter from 1mm-25mm located along the lymphatic vessels.

Afferent vessels

Carry lymph to the lymph node.

Efferent vessels

Carry lymph away from the lymph node.

Dendritic cells

White blood cell derived from a monocyte that has projections and serves as an antigen presenting cell.

Appendicitis

Inflammation of the lymphoid tissues of the appendix.

Thymosins

Hormones of the thymus gland.

Antibody

A Y-shaped protein produced by activated B lymphocytes that binds to a specific antigen.

Artificially acquired passive immunity

Could be acquired through a gamma globulin treatment.

Naturally acquired passive immunity

Acquired through transfer of maternal antibodies across the placenta or in breast milk.

Artificially acquired active immunity

Acquired through vaccine.

Naturally acquired active immunity

Acquired through exposure to antigens in the environment (getting a disease).

Blood-thymus barrier

Regulates exchange of substances between the circulatory system and the thymus, providing an isolated environment for the development of T cells.

Spleen

A lymphoid organ important for the phagocytosis of red blood cells, the immune response and lymphocyte production.

Splenectomy

Removal of the spleen.

Pulp

The cellular components within the spleen.

Red pulp

Portions of the spleen that contain large quantities of red blood cells.

White pulp

Portions of the spleen that contain large quantities of white blood cells.

Immunity

The ability to fight infection.

Innate defenses

Do not distinguish one type of threat from another. Their response is the same regardless of the type of invading agent.

Physical barriers

Skin, mucous membranes, hair, etc. that keep hazardous organisms and materials outside the body.

Phagocytes

Cells that engulf pathogens and cell debris. Examples are neutrophils, eosinophils and macrophages.

Immune surveillance

Destruction of abnormal cells by NK cells.

Interferons

Chemicals that coordinate the defenses against viral infections.

Complement

A system of circulating proteins that assists antibodies in the destruction of pathogens.

Inflammation

A localized, tissue-level response that tends to limit the spread of an injury or infection, including redness, heat, swelling and pain.

Fever

An elevation of body temperature that accelerates tissue metabolism and defenses.

Diapedesis

The movement of white blood cells through the walls of blood vessels by migration between adjacent endothelial cells.

Chemotaxis

The attraction of phagocytes to the source of abnormal chemicals in tissue fluids.

Pyrogens

Fever inducing proteins.

Adaptive immunity

Coordinated and produced by T cells and B cells.

Vaccines

Stimulate an immune response by producing antibodies to a specific disease; contain either a killed or attenuated pathogen.

Properties of adaptive immunity

Specificity, versatility, immunologic memory, and tolerance.

MHC proteins

Surface antigens that are genetically determined and important to the recognition of foreign antigens.

MHC I proteins

Present in the membranes of all nucleated cells.

MHC II proteins

Present only in membranes of antigen-presenting cells; appear in the plasma membrane only when processing antigens.

Antigen presenting cells

Specialized cells that include all of the phagocytic cells of the monocyte-macrophage group and the dendritic cells of the skin and lymphoid organs.

Antigen recognition

T-cell binding that occurs only if the MHC protein contains the antigen that the T cell is programmed to detect.

CD8 markers

Found on CD8 T cells; respond to antigens presented by Class I MHC proteins.

CD4 markers

Found on CD4 T cells; respond to antigens presented by Class II MHC proteins.

Sensitization

Antigens brought into the B cell by endocytosis subsequently appear on the surface of the B cell, bound to Class II MHC proteins.

Antibodies

Small, soluble proteins that bond to specific antigens; Y shaped with heavy chains and light chains.

Immunoglobulins (Igs)

Antibodies.

IgG

Antibodies that account for 80% of all antibodies; responsible for resistance against many viruses, bacteria and bacterial toxins.

IgE

Attach as an individual molecule to the exposed surfaces of basophils and mast cells.

IgD

Individual molecules on the surfaces of B cells, where they can bind antigens in the extracellular fluid.

IgM

The first class of antibody secreted after an antigen is encountered; concentration declines as IgG production accelerates.

IgA

Found primarily in glandular secretions such as mucus, tears, saliva, and semen. These antibodies attack pathogens before they gain access to internal tissues.

Primary response

The initial response to antigen exposure.

Secondary response

The more extensive and prolonged response that occurs when an antigen is encountered a second time.

Neutralization

A method by which antibodies work in which the antibodies bind to sites on the antigen that prevent them from being able to bind to the plasma membrane of body cells.

Prevention of pathogen adhesion

A method by which antibodies work in which they cover the surfaces of bacteria or viruses making it difficult for them to adhere to or penetrate surfaces.

Activation of complement

When bound to an antigen, portions of the antibody molecule change shape, exposing areas that bind complement proteins. The bound complement molecules then activate the complement system.

Opsonization

The attraction and enhancement of phagocytosis due to the coating of an object with antibodies.

Attraction of phagocytes

Antigens covered with antibodies attract phagocytes.

Stimulation of inflammation

Antibodies may promote inflammation by stimulating basophils and mast cells to release chemicals.

Allergies

Inappropriate or excessive immune responses to antigens.

Allergens

Antigens that trigger allergic reactions.

Immediate hypersensitivity

A rapid and especially severe response to the presence of an antigen.

Hypersensitivity reaction

Reaction restricted to the body surface.

Anaphylaxis

A reaction in which mast cells throughout the body are affected releasing histamines and other chemicals. Extensive peripheral vasodilation occurs, producing a blood pressure that can lead to circulatory collapse.

Autoimmune disorders

When B cells make antibodies against normal body cells and tissues (autoantibodies). The condition produced depends on the specific antigen attacked by autoantibodies.