Lymphatic and Immune Systems - Innate and Adaptive Immunity Vocabulary Flashcards

Comprehensive vocabulary flashcards covering the lines of defense, innate and adaptive immunity, mechanisms of phagocytosis, types of phagocytes, antimicrobial proteins, natural killer cells, and acute inflammation from Chapter 17.

First Line of Defense

External barriers that keep most pathogens at bay, including skin, mucous membranes, and their secretions.

Second Line of Defense

Innate mechanisms produced if a pathogen penetrates external barriers, including phagocytic white blood cells, antimicrobial proteins, natural killer cells, an inflammatory response, and fever.

Third Line of Defense

Adaptive mechanisms employing lymphocytes ($T$ and $B$ cells) and antibodies to target and rid the body of unwanted pathogens.

Innate Immune System

A type of immunity present from birth that repels a wide variety of threats, responds immediately, and retains no memory of the pathogen.

Adaptive Immune System

A type of immunity (also called specific immunity) that develops during life from exposure to specific pathogens, responds slowly over days, and retains a memory of the pathogen.

Primary Immune Response

The initial immune defense mounted upon the body's first exposure to a particular pathogen through infection or vaccination.

Secondary Immune Response

A faster and stronger immune defense triggered by subsequent exposure to a specific pathogen, enabled by the immune system's memory.

Acid Mantle

A thin layer of acid produced by sweat on the skin's surface that inhibits bacterial growth.

Lysozyme

An enzyme present in mucus, tears, and saliva that weakens the cell walls of certain bacteria, aiding in their destruction.

Phagocytes

Cells whose sole job is to ingest and destroy microorganisms and other small particles.

Pseudopods

Membrane projections (or "false feet") sent out by a phagocyte to envelop a microorganism.

Phagosome

A complete sac formed inside a phagocyte when pseudopods envelop a microorganism.

Phagocytosis Process

The sequence of ingestion where a phagocyte extends pseudopods around a microorganism, encloses it in a phagosome, fuses it with a lysosome containing digestive enzymes, destroys it, and releases waste products.

Macrophages

Important phagocytes (meaning "large eater") that evolve from monocytes migrating into connective tissues; they tend to remain fixed in strategic areas such as the lung alveoli, liver, nerve tissue, bone, and spleen.

Neutrophils

Important phagocytes that roam the body seeking out bacteria, summoned to infection sites via chemotaxis, and capable of creating a toxic killing zone.

Chemotaxis

The process by which immune cells like neutrophils are summoned or drawn to sites of infection or tissue damage by chemical signals released from inflamed cells.

Diapedesis

The process in which neutrophils anchor to the inside of a capillary and squeeze through spaces between endothelial cells to enter inflamed tissue.

Extravasated

Describing cells and chemicals that have left the bloodstream and passed into the surrounding tissue.

Killing Zone

An area around a neutrophil formed by secreted toxic chemicals that kills bacteria beyond what phagocytosis can achieve, though destroying the neutrophil in the process.

Pus

A thick yellowish fluid created by accumulated dead phagocytes (especially neutrophils), tissue debris, and fluid during an infection.

Abscess

An accumulation of pus within a tissue cavity.

Interferons

Proteins produced and released by virus-infected cells that bind to surface receptors on neighboring cells, triggering enzyme production to prevent viral replication.

Complement System

A group of more than 20 proteins circulating in an inactive form in the bloodstream that, when activated, start a chemical cascade to coat pathogens, augment inflammation, and kill bacteria.

Membrane Attack Complex

A group of complement proteins that embed into a bacterium's plasma membrane in ring-like circles, forming openings that allow fluid and sodium ($Na^+$) to enter, causing the bacterium to swell and burst.

Natural Killer (NK) Cells

A unique group of lymphocytes that continually roam the body, recognizing and destroying foreign cells, cancer cells, virus-infected cells, and transplanted organ cells primarily through chemical lysis.

Acute Inflammation

A response to tissue injury (from trauma, ischemia, or infection) that stimulates defenses to fight infection, contain pathogens, and clean up and repair damaged tissue.

Histamine

A chemical released by injured cells that dilates local blood vessels and causes endothelial cells in capillary walls to separate slightly.

Hyperemia

Increased blood flow to an injured area resulting from vasodilation, which brings leukocytes, oxygen, and amino acids while flushing out toxins and wastes.

Cytokines

Small proteins serving as a chemical communication network among immune cells; released by damaged tissues to prompt bone marrow release of neutrophils and summon other immune cells.

Fibrinogen

A plasma protein that leaks into injured tissue and forms a sticky clot, walling off the infected area to prevent the spread of infection.

Four Classic Signs of Inflammation

Redness (from hyperemia), heat (from hyperemia), swelling (from capillary fluid leakage), and pain (from nerve injury, swelling pressure, or bacterial toxins).

-itis

A medical suffix denoting inflammation (e.g., dermatitis, tonsillitis, arthritis).