BIO 2341: Lymphatic and Immune Systems (Chapters 20 & 21)

A comprehensive vocabulary review of Chapters 20 and 21 covering key anatomical structures, cellular components, and physiological processes of the lymphatic and immune systems.

Thoracic duct

The major lymphatic vessel that returns lymph from most of the body back to venous circulation, emptying at the left internal jugular-subclavian venous junction.

Right lymphatic duct

The lymphatic duct that drains lymph exclusively from the right upper quadrant of the body into venous circulation at the right internal jugular-subclavian junction.

Lacteal

A specialized lymphatic capillary located within an intestinal villus that absorbs dietary lipids.

Spleen

A secondary lymphoid organ that filters blood rather than lymph, removing old erythrocytes and facilitating immune surveillance.

Thymus

A primary lymphoid organ located in the mediastinum where T-cell precursors complete their maturation and achieve immunocompetence.

Neutrophil

A phagocytic leukocyte that is typically among the first immune cells to arrive at an acute site of infection.

MHC class I

A surface molecule found on nucleated host cells that presents intracellular antigens to CD8-positive cytotoxic T cells.

MHC class II

A surface molecule found predominantly on professional antigen-presenting cells that displays extracellular antigens to CD4-positive helper T cells.

IgE

An antibody class predominantly involved in allergic reactions and host defense against parasitic worms.

Plasma cell

An antibody-secreting effector cell that differentiates from an activated B lymphocyte.

Opsonization

The immune process of coating a microbe with antibodies or complement proteins to enhance its recognition and engulfment by phagocytes.

Dendritic cell

A professional antigen-presenting cell in tissues that is especially potent at processing antigens and activating naive T cells.

Passive artificial immunity

Temporary immunity conferred by the medical administration of exogenous antibodies, such as rabies immunoglobulin.

Adaptive immunity

The branch of the immune system that provides targeted protection, develops antigen-specific immunologic memory, and exhibits a delayed initial onset.

Innate immunity

The nonspecific, rapid branch of the immune system that provides immediate defense upon exposure to pathogens without developing immunologic memory.

Afferent lymphatic vessel

A lymphatic vessel that carries unfiltered lymph into the convex surface of a lymph node.

Efferent lymphatic vessel

A lymphatic vessel that conveys filtered lymph away from the hilum of a lymph node.

Chyle

Milky, lipid-rich lymph collected from the lacteals of the small intestine after the absorption of dietary fat.

MALT

Mucosa-associated lymphoid tissue that guards mucosal membranes and entry points against pathogen entry.

Macrophage

A long-lived tissue-resident phagocyte derived from a monocyte that engulfs foreign debris and can act as an antigen-presenting cell.

Cytokine

A small signaling protein secreted by cells that mediates and regulates immune and inflammatory responses.

Epitope

The specific localized portion or determinant of an antigen recognized and bound by an immune receptor or antibody.

Complement

A group of circulating plasma proteins that, when activated, enhances inflammation, promotes opsonization, and causes microbial lysis.

Diapedesis

The active passage or extravasation of leukocytes through intact blood vessel walls into surrounding interstitial tissue.

Memory cell

A long-lived descendant of an activated lymphocyte that remains in lymphoid tissues to mount a faster and stronger secondary immune response upon subsequent antigen exposure.

Cisterna chyli

An enlarged sac-like dilation in the abdomen that collects fatty chyle and lymph from the lower body before it ascends into the thoracic duct.

Hematopoiesis

The formation and development of all blood cells occurring within the red bone marrow.

Apoptosis

Programmed, orderly cell death triggered in target cells by natural killer cells and cytotoxic T cells.

PAMPs

Pathogen-associated molecular patterns; conserved molecular structures shared by microbes that are recognized by innate immune receptors.

PRRs

Pattern recognition receptors; innate cellular receptors that bind to common microbial molecular patterns (PAMPs).

Histamine

A vasoactive chemical mediator released by mast cells and basophils that causes vasodilation and increases vascular permeability.

IgA

An antibody class prominent in external secretions such as saliva, tears, colostrum, and breast milk, protecting mucosal surfaces.

IgM

The first class of antibody synthesized and secreted by plasma cells during a primary immune response.

CD4

A coreceptor glycoprotein present on helper T cells that binds specifically to MHC class II molecules.

Pyrogens

Substances that reset the body's hypothalamic thermostat to a higher set point, inducing a fever.

Immunocompetence

The ability of a lymphocyte to recognize a specific foreign antigen and mount or participate in an adaptive immune response.

Phagocytosis

The cellular process by which a cell contacts, engulfs, digests, and destroys a microbe, damaged cell, or debris.

Co-stimulation

A mandatory secondary signal required alongside antigen recognition to achieve full activation of a naive lymphocyte.

Clonal expansion

The rapid mitotic proliferation of an activated lymphocyte to produce a population of identical daughter cells with the same antigen specificity.

Hypersensitivity

An excessive or inappropriate immune response to an otherwise harmless environmental antigen, such as pollen, dander, or medication.

Primary lymphoid structures

Sites of lymphocyte development and immunocompetence, consisting of the red bone marrow and the thymus.

Secondary lymphoid structures

Sites where mature, immunocompetent lymphocytes encounter antigens and initiate immune responses, including lymph nodes, spleen, tonsils, and MALT.

Humoral immunity

The branch of adaptive immunity mediated by B cells and antibodies that primarily targets extracellular pathogens and soluble toxins.

Cell-mediated immunity

The branch of adaptive immunity mediated by T cells that targets infected host cells, malignant cells, and foreign grafts.