Leukocytes: Production, Development, and Function

Vocabulary flashcards covering leukocyte types, development, and functions as described in the notes.

Leukocytes

White blood cells; immune cells produced in red bone marrow via leukopoiesis; defend against injury, infection, and disease.

Leukopoiesis

Production of leukocytes in red bone marrow from hematopoietic stem cells; proceeds through progenitor stages to mature leukocytes.

Hematopoietic (hemopoietic) stem cells

Stem cells in red bone marrow that give rise to all blood cells; differentiate into colony forming units for leukocyte lineages.

Red bone marrow

Primary site of leukocyte production and differentiation.

Interstitial fluid

Fluid surrounding tissues; contains more leukocytes than blood at any given time, and leukocytes migrate into it during immune responses.

Diapedesis

Movement of leukocytes through capillary walls into surrounding tissues, typically via intercellular clefts.

Chemotaxis

Directed movement of leukocytes toward chemical signals released from damaged cells or pathogens.

Inflammation

Non-specific immune response characterized by vasodilation and filtration of plasma into interstitial tissue.

Specific granules

Secretory vesicles in some leukocytes that contain enzymes or cytotoxic chemicals involved in immune responses.

Lysozyme

Antimicrobial enzyme found in leukocytes that can break down bacterial cell walls.

Granulocytes

Leukocytes that contain specific granules; include neutrophils, eosinophils, and basophils.

Neutrophils

Most abundant granulocytes; first responders to bacterial infection; highly phagocytic.

Eosinophils

Granulocytes involved in defense against parasites and in allergic reactions.

Basophils

Granulocytes that release histamine and participate in inflammation and allergic responses.

Agranulocytes

Leukocytes that lack specific granules; include lymphocytes and monocytes.

Lymphocytes

Agranulocytes that include B cells, T cells, and natural killer cells; develop in the thymus after leaving bone marrow and can survive for decades.

Monocytes

Agranulocytes that circulate briefly in blood and differentiate into macrophages in tissues; macrophages can survive for years.

Macrophages

Matured monocytes in tissues; phagocytic cells that can live for years and orchestrate immune responses.

B lymphocytes

Lymphocytes that mature to produce antibodies; derived from lymphoblasts.

T lymphocytes

Lymphocytes involved in cell-mediated immunity; mature in the thymus.

Natural killer cells

Lymphocytes providing innate immune defense against virus-infected and tumor cells; do not require prior antigen exposure.

Colony Forming Units (CFUs)

Progenitor cells formed from hematopoietic stem cells; each CFU gives rise to a specific leukocyte lineage.

Colony Stimulating Factors (CSFs)

Cytokines that stimulate CFUs to differentiate into particular leukocyte types depending on bodily needs.

Blast cells

Early progenitors (e.g., myeloblasts, monoblasts, lymphoblasts) that differentiate into lineage-specific cells through intermediate stages.