Lymphatic System & Immunology – Key Vocabulary

Vocabulary flashcards covering essential terms and definitions from the lymphatic system, innate and adaptive immunity, antibodies, vaccines, and immune system changes.

Lymphatic System

A network of vessels, organs, and tissues that returns interstitial fluid to blood, absorbs fats, and houses immune cells.

Functions of the Lymphatic System

1) Drains excess interstitial fluid, 2) Transports dietary lipids, 3) Provides immune responses.

Lymph Node

Small bean-shaped organs that filter lymph; contain lymphocytes and macrophages to initiate immune responses.

Cortex (Lymph Node)

Outer region rich in B-cell–containing follicles for antibody production.

Medulla (Lymph Node)

Inner region containing T cells, plasma cells, and macrophages that destroy pathogens.

Common Lymph-Node Clusters

Cervical, axillary, and inguinal regions.

Lymphatic Nodule

Unencapsulated lymphoid tissue found in mucosa (e.g., tonsils, Peyer’s patches, appendix).

Spleen

Largest lymphoid organ; LUQ of abdomen; filters blood, recycles RBCs, and stores platelets & iron.

Metastasis via Lymphatics

Cancer cells enter lymph vessels, travel to nodes, and spread to distant sites.

Cancerous vs. Infected Nodes

Cancerous: hard, non-tender, fixed; Infected: tender, soft, movable, often enlarged quickly.

Lines of Defense

1st: physical/chemical barriers (innate), 2nd: cells & inflammation (innate), 3rd: adaptive immunity (specific).

Phagocytosis

Ingestion and destruction of microbes by neutrophils and macrophages.

Inflammation

Localized tissue response to injury that limits spread of pathogens and initiates repair.

Stages of Inflammation

1) Vasodilation & increased permeability, 2) Phagocyte emigration, 3) Tissue repair.

Cardinal Signs of Inflammation

Redness, heat, swelling, pain; caused by increased blood flow, permeability, and chemical mediators.

Fever

Systemic rise in body temperature that inhibits microbes and enhances immune activity.

Adaptive Immunity

Specific defense involving lymphocytes that recognize antigens and remember them.

Humoral (Antibody-Mediated) Immunity

B cells in blood/tissue fluids secrete antibodies to neutralize extracellular pathogens.

Cell-Mediated Immunity

Cytotoxic T cells destroy infected or abnormal cells in tissues.

Primary Immune Response

First exposure; slow, low antibody titer; forms memory cells.

Secondary Immune Response

Subsequent exposure; rapid, high antibody titer due to memory cells.

Antibody (Immunoglobulin)

Y-shaped protein made by B cells that binds specific antigen.

IgM

First antibody produced; indicates recent infection; excellent complement activator.

IgG

Most abundant; crosses placenta; provides long-term immunity.

IgA

Found in secretions (saliva, milk, mucous); protects mucosal surfaces.

IgE

Binds mast cells; mediates allergic reactions and defense against parasites.

Functions of Antibodies

Neutralization, opsonization, complement activation, agglutination/precipitation.

Major Histocompatibility Complex (MHC)

Cell-surface proteins that present antigen fragments to T cells for recognition.

Natural Active Immunity

Immunity gained after infection; body produces its own antibodies & memory cells.

Natural Passive Immunity

Antibodies transferred from mother to fetus/infant (placenta, breast milk).

Artificial Active Immunity

Immunity produced by vaccination with antigenic material.

Artificial Passive Immunity

Injection of preformed antibodies (e.g., antivenom) for immediate, short-term protection.

Live Attenuated Vaccine

Contains weakened pathogens; elicits strong, long-lasting immunity.

Inactivated (Killed) Vaccine

Contains dead microbes; safer but often requires boosters.

Subunit/Conjugate Vaccine

Uses specific antigens or linked polysaccharide-protein; reduced side effects.

Toxoid Vaccine

Contains inactivated toxins to induce immunity against toxin-producing bacteria.

Booster Shot

Additional dose that re-exposes immune system, amplifying memory and antibody levels.

Herd Immunity

Protection of non-immune individuals when a critical portion of the population is immune.

Hypersensitivity

Undesirable immune response such as allergy or autoimmunity.

Immunosenescence

Age-related decline in immune function: reduced T-cell activity, lower antibody response.