Immune System (Part I: Innate Immune System)

Flashcards of key vocabulary terms related to the Innate Immune System.

Innate Immune System

The part of the immune system that includes external body membranes (like skin and mucosae) and internal defenses (like phagocytes and antimicrobial proteins); it is nonspecific and provides a first and second line of defense.

Adaptive Immune System

The part of the immune system that involves B and T lymphocytes and is highly specific, providing the body's third line of defense; it takes considerable time to activate.

Immunity

Resistance to disease conferred by the immune system.

Pathogens

Harmful or disease-causing microorganisms.

Skin

A physical barrier and part of the surface barriers with a heavily keratinized epithelial membrane that is resistant to most weak acids, weak bases, bacterial enzymes, and toxins.

Mucous Membranes

Line all body cavities that open to the exterior, trapping microorganisms and containing enzymes like lysozyme.

Lysozyme

An enzyme found in saliva and lacrimal fluid that destroys bacteria.

Phagocytes

Cells that engulf or "eat" pathogens.

Macrophages

Phagocytic cells derived from monocytes that leave the bloodstream and enter tissue to search for cellular debris or foreign invaders.

Neutrophils

The most abundant type of white blood cell that may become phagocytic upon exposure to infectious material and secrete defensins.

Defensins

Antibiotic-like chemicals secreted by neutrophils.

Eosinophils

Weak phagocytes that are important against parasitic worms and discharge destructive contents of cytoplasmic granules.

Mast Cells

Cells involved in allergies that have some phagocytic capabilities.

Phagosome

A membrane-lined vacuole that encloses a particle engulfed by a phagocyte.

Phagolysosome

Formed when a lysosome fuses with a phagosome; pathogen killed and digested within it.

Opsonization

The coating of foreign particles with complement proteins and antibodies to increase adherence during phagocytosis.

Natural Killer (NK) Cells

Large granular lymphocytes that can kill and lyse cancer cells and virus-infected body cells by releasing cytolytic chemicals called perforins.

Inflammation

Triggered by body tissue injuries and results in redness, heat, swelling, pain, and sometimes impairment of function.

Histamine

An inflammatory mediator that causes vasodilation and increased permeability of local capillaries.

Exudates

Fluid containing proteins like clotting factors and antibodies that flows from the bloodstream into tissue spaces during inflammation.

Leukocytosis

The release of neutrophils from red bone marrow induced by chemicals released from injured cells.

Margination

The process of neutrophils clinging to the capillary wall due to cell adhesion molecules (CAMs).

Diapedesis

The process of neutrophils emigrating through the capillary walls to the site of inflammation.

Chemotaxis

The attraction of neutrophils and other white blood cells to the site of injury due to inflammatory chemicals.

Pus

A mixture of dead or dying neutrophils, broken-down tissue cells, and living and dead pathogens.

Abscesses

Sacs of pus walled off by collagen fibers.

Granulomas

Tumorlike growths containing macrophages infected by pathogens surrounded by uninfected macrophages and an outer fibrous capsule.