Adaptive Immunity – Specific Defenses of the Host (Chapter 17, Part 1)

Vocabulary flashcards summarizing major terms and definitions related to adaptive immunity, its branches, types, and key molecular mediators.

Adaptive immunity

Defense system that targets specific pathogens; develops after exposure and generates memory for faster secondary responses.

Primary immune response

The immune system’s initial reaction to a particular foreign substance, occurring the first time the antigen is encountered.

Secondary immune response

A faster, more effective reaction upon later exposure to the same antigen, due to immunological memory.

Humoral immunity

Branch of adaptive immunity involving antibody production by B lymphocytes; most effective against toxins, extracellular bacteria, and viruses before cell entry.

Cellular (cell-mediated) immunity

Branch of adaptive immunity driven by specialized T lymphocytes that attack infected or abnormal cells; effective against intracellular pathogens and altered host cells.

B lymphocytes (B cells)

Lymphocytes that mature in the bone marrow and are responsible for producing antibodies in humoral immunity.

T lymphocytes (T cells)

Lymphocytes that mature in the thymus and orchestrate cellular immunity, including helper (TH) and cytotoxic (TC) subsets.

Naturally acquired active immunity

Protection resulting from infection in which the host’s own immune system produces antibodies and memory cells.

Naturally acquired passive immunity

Short-term protection gained from antibodies transferred across the placenta or through colostrum to the infant.

Artificially acquired active immunity

Immunity produced by vaccination, where exposure to antigens stimulates the host to generate its own immune response.

Artificially acquired passive immunity

Immediate, short-term protection obtained by the injection of preformed antibodies.

Cytokines

Chemical messengers released by immune cells in response to stimuli that regulate immunity, inflammation, and hematopoiesis.

Interleukins (ILs)

Cytokines that facilitate communication between leukocytes to coordinate immune responses.

Chemokines

Cytokines that induce chemotaxis, guiding the migration of leukocytes to sites of infection or injury.

Interferons (IFNs)

Cytokines that interfere with viral replication inside host cells and activate immune defenses.

Tumor necrosis factor alpha (TNF-α)

Cytokine primarily involved in inflammation and the systemic responses to infection and cancer.

Hematopoietic cytokines

Cytokines that control the differentiation and proliferation of stem cells into various blood cell types.

Antigen

A substance—often a component of invading microbes—that provokes an immune response and leads to antibody production.

Epitope (antigenic determinant)

The specific region on an antigen that is recognized and bound by an antibody.

Hapten

A small molecule incapable of provoking an immune response unless attached to a larger carrier molecule.