Overview of the Immune System

This set of flashcards covers key terminology and concepts related to the immune system, its functions, responses, and historical context.

Immunology

The study of the immune system and its functions.

Pathogen

Any microorganism that can cause disease.

Antigen

A substance that induces an immune response, typically a foreign substance.

Passive Immunity

Immunity acquired through the transfer of antibodies from one individual to another.

Active Immunity

Immunity that occurs as a result of natural infection or vaccination leading to the production of antibodies.

Vaccine

A preparation that stimulates an immune response without causing the disease.

Phagocytosis

The process by which certain cells, called phagocytes, engulf and digest microorganisms and cellular debris.

Humoral Immunity

A component of the immune response that involves antibodies produced by $B$ cells to fight pathogens.

Cell-Mediated Immunity

The immune response that does not involve antibodies but rather the activation of phagocytes and $T$ cells.

Cytokines

Signaling proteins that mediate and regulate immunity, inflammation, and hematopoiesis.

Self/Non-self Discrimination

The ability of the immune system to recognize which cells are part of the body and which are foreign.

Immunological Memory

The capacity of the immune system to remember previous encounters with pathogens.

Allergy

An abnormal immune response to a substance that is typically harmless to most people.

Autoimmunity

A condition in which the immune system mistakenly attacks the body’s own cells.

Epidemiology

The study of how diseases affect the health and illness of populations.

Attenuated Vaccine

A vaccine created from weakened pathogens that are still able to replicate and induce an immune response without causing disease.

Anaphylaxis

A severe, potentially life-threatening allergic reaction.

Pathogenesis

The biological mechanism that leads to the development of a disease.

Haptens

Small molecules that, when combined with a larger carrier such as a protein, can elicit an immune response.

Circulating Antibodies

Antibodies present in the blood that help identify and neutralize foreign objects like bacteria and viruses.

Clonal Selection Theory

The theory that a specific antigen selectively binds to and activates a specific $B$ or $T$ cell, leading to proliferation and differentiation.

Complement System

A part of the immune system that enhances the ability of antibodies and phagocytic cells to clear microbes and damaged cells.

Innate Immunity

The first line of defense against pathogens that provides a general, non-specific, and immediate response.

Adaptive Immunity

A specific immune response that develops over time and provides long-term protection through immunological memory.

Major Histocompatibility Complex (MHC)

A set of cell surface proteins essential for the acquired immune system to recognize foreign molecules in vertebrates.

Inflammation

A biological response to harmful stimuli, such as pathogens or tissue damage, characterized by redness, heat, swelling, and pain.

Antibody (Immunoglobulin)

A Y-shaped protein produced by $B$ cells that is used by the immune system to identify and neutralize foreign objects.

Epitope

The specific part of an antigen that is recognized by the immune system, specifically by antibodies, $B$ cells, or $T$ cells.

Adjuvant

A substance added to a vaccine that enhances the body's immune response to an antigen.

Natural Killer (NK) Cells

A type of cytotoxic lymphocyte critical to the innate immune system that responds to virally infected cells and tumors.

Primary Immune Response

The immune response occurring on the first exposure to an antigen, characterized by a lag phase before antibodies appear.

Secondary Immune Response

The faster and more intense immune response that occurs upon subsequent exposures to the same antigen due to memory cells.