Immune System Vocabulary Flashcards

Vocabulary flashcards covering key immune system concepts from the lecture notes.

Innate immune response

The non-specific first line of defense present from birth, including barriers and fast-acting cells; does not form memory.

Barriers

Physical/chemical barriers (skin, mucosal surfaces, secretions) that block or slow pathogen entry.

Defensins

Antimicrobial peptides produced by various cells that inhibit bacteria.

Interferon

Signaling proteins produced early in infection that help limit viral replication and modulate immune responses.

Cytokines

Signaling molecules coordinating immune responses; diverse, pleiotropic functions.

Complement proteins

Blood proteins that help attack pathogens (opsonization, inflammation) and are activated in the bloodstream.

Neutrophils

A granulocyte; first responder to infection and highly phagocytic.

Macrophage

Large tissue phagocyte derived from monocytes; engulfs pathogens and presents antigens.

Monocytes

Circulating white blood cells that differentiate into macrophages or dendritic cells in tissues.

Dendritic cells

Antigen-presenting cells that initiate adaptive immunity by activating T cells.

Natural killer cells

Innate lymphocytes that detect stressed or infected cells and kill them without prior exposure.

Erythrocytes

Red blood cells; transport oxygen via hemoglobin; anucleate and not directly involved in immunity.

Hematopoietic stem cells

Bone marrow stem cells that give rise to all blood cells (red and white).

Erythropoietin

Hormone that stimulates red blood cell production in the bone marrow.

Platelets

Cell fragments that aid in blood clotting and wound repair.

Leukocytes

White blood cells; diverse group responsible for immune responses.

Lymphocytes

White blood cells abundant in lymph; include B cells, T cells, and NK cells.

PMNL (polymorphonuclear leukocytes)

Group of white blood cells with multi-lobed nuclei—neutrophils, eosinophils, basophils.

B cells

Lymphocytes that can differentiate into antibody-producing plasma cells.

T cells

Lymphocytes that mediate cell‑based immunity; include cytotoxic and helper subsets.

B cell receptor

Membrane-bound antibody on B cells that recognizes specific antigens.

T cell receptor

Membrane-bound receptor on T cells that recognizes antigenic peptides presented by MHC.

Cytotoxins

Molecules produced by cytotoxic cells that kill target cells (e.g., infected or abnormal cells).

Memory

Adaptive immune memory; enhanced and faster response upon re-exposure to the same antigen.

MHC I

Major histocompatibility complex class I; presents endogenous peptides to CD8+ T cells and influences tissue compatibility.

MHC II

Major histocompatibility complex class II; presents exogenous peptides to CD4+ T cells on professional APCs.

Antigen

Foreign molecule recognized by the immune system and capable of triggering an immune response.

Antigen-specific immune response

Adaptive immunity; learns to target specific antigens via B and T cell responses.

Pluripotent

Stem cells that can differentiate into many, but not all, cell types.

Totipotent

Stem cells that can differentiate into all cell types, including extraembryonic tissues.