Chapter 1 Vocabulary: Morphology and Maturation of Human Blood Cells (Hematopoiesis)

A set of vocabulary flashcards covering key concepts, cell types, and stages of hematopoiesis and blood cell morphology from Chapter 1 notes.

Hematopoiesis

The dynamic process of production and development of all blood and marrow cells; all blood cells derive from hematopoietic stem cells (HSCs).

Hematopoietic stem cells (HSCs)

Pluripotent stem cells that continuously self-renew and differentiate into every blood cell lineage; reside in specialized bone marrow niches.

Stem cell niche

A specialized microenvironment in bone marrow that provides signals supporting HSC self-renewal and multilineage repopulation.

Extramedullary hematopoiesis

Blood cell production outside the bone marrow, a compensatory mechanism when marrow cannot meet demand.

Buffy coat

The layer containing white blood cells and platelets after centrifugation of blood.

Plasma

The liquid component of blood (about 55% of blood) composed mainly of water with proteins and other solutes.

Albumin

Major plasma protein (about 55% of plasma proteins) that contributes to oncotic pressure.

Globulins

Plasma proteins making up about 38% of plasma proteins; involved in immune function and transport.

Fibrinogen

Plasma protein essential for coagulation; accounts for about 7% of plasma proteins.

RBCs (erythrocytes)

Mature red blood cells responsible for oxygen transport; biconcave discs 7–8 μm in diameter with no nucleus.

WBCs (leukocytes)

Nucleated cells of the immune system that defend against infection; include neutrophils, eosinophils, basophils, lymphocytes, and monocytes.

Platelets (thrombocytes)

Anucleate cytoplasmic fragments (~1–4 μm) essential for hemostasis; contain granules and are found in the buffy coat.

Segemented neutrophil

Neutrophil with a multilobed nucleus (2–5 lobes) connected by filaments; cytoplasm pink; secondary granules contain alkaline phosphatase.

Band neutrophil

Immature neutrophil with a horseshoe-shaped nucleus; edges nearly parallel; normally 2–6% of neutrophils.

Eosinophil

Granulocyte with large orange-red granules; 0–4% of WBCs; granules 0.2–1.0 μm; cytoplasm pink to orange.

Basophil

Granulocyte with large violet-blue granules; 0–2% of WBCs; granules coarse and variable in size.

Lymphocyte

Mononuclear leukocyte (20–44% of WBCs); small with round nucleus and clumped chromatin; pale blue cytoplasm.

Monocyte

Largest WBC; gray-blue cytoplasm with fine granules; nucleus with folds/convolutions; 2–9% of WBCs.

Plasmacyte (plasma cell)

Mature B cell that produces antibodies; eccentrically placed nucleus and deep blue cytoplasm with perinuclear clearing.

Pronormoblast (rubriblast, proerythroblast)

Earliest recognizable erythroid precursor; round nucleus with nucleoli; distinct dispersed chromatin.

Basophilic normoblast (prorubricyte, basophilic erythroblast)

erythroid precursor with basophilic cytoplasm and coarsened chromatin pattern.

Polychromatophilic normoblast (rubricyte, polychromatophilic erythroblast)

Smaller erythroblast with pink (Hb) and blue (RNA) cytoplasm; late stage where pink often dominates.

Orthochromatic normoblast (metarubricyte, orthochromatic erythroblast)

Nucleated erythroblast with pyknotic nucleus; cytoplasm largely polychromatic; final nucleated erythroid stage.

Reticulocyte

Anucleate erythrocyte with residual RNA; polychromatic cytoplasm; visualized with special stains (e.g., methylene blue).

Erythrocyte (discocyte)

Mature red blood cell; nucleus- and organelle-free; flexible disc important for microcirculation passage.

Myelopoiesis (granulocytopoiesis)

Production and maturation of granulocytes (neutrophils, eosinophils, basophils) and monocytes.

Myeloblast

Earliest recognizable granulocytic precursor; round reddish-blue nucleus; delicate chromatin; minimal cytoplasm; no granules.

Promyelocyte

Granulocytic precursor with prominent primary granules and a large nucleus with nucleoli.

Neutrophilic myelocyte

Granulocytic precursor with round/oval nucleus and secondary pinkish granules.

Neutrophilic metamyelocyte

Granulocytic precursor with bean-shaped nucleus; indentation and abundant pink secondary granules.

Megakaryocyte

Largest bone marrow cell; multilobulated nucleus; cytoplasm fragments to form platelets.

Megakaryocytopoiesis

Process by which megakaryocytes proliferate and fragment to form platelets.

Monopoiesis

Monoblasts → promonocytes → monocytes → macrophages.

Lymphopoiesis

Development of lymphoid cells (T, B, NK) from HSCs; occurs in thymus and bone marrow for maturation; secondary organs coordinate immune responses.

Lymphoblast

Large lymphoid precursor with a large nucleus, thin chromatin, and nucleoli.

Prolymphocyte

Intermediate chromatin pattern in lymphoid development; clumped chromatin; characteristic paranuclear chromatin features.

Plasmablast

Early antibody-secreting B-cell precursor with large nucleus and fine chromatin; plasmacytic differentiation begins.

Proplasmacyte

Precursor to plasmacyte with blue cytoplasm and prominent juxtanuclear area; nucleus often eccentric.

Diapedesis

Movement of leukocytes across endothelium into tissues during immune response.

Cytokines

Soluble glycoprotein mediators secreted by cells to promote proliferation, differentiation, growth, or apoptosis of target cells.

G-CSF

Growth factor that stimulates neutrophil production; used clinically to treat neutropenia.

GM-CSF

Granulocyte-macrophage colony-stimulating factor; stimulates multiple lineages including granulocytes and macrophages.

EPO

Erythropoietin; growth factor that stimulates erythroid precursor proliferation and differentiation.

Myeloid:Erythroid (M:E) ratio

Ratio of myeloid to erythroid precursors in bone marrow; about 4:1 in healthy adults.

Osteoclast

Giant (>100 µm) multinucleated, irregularly shaped marrow phagocytes responsible for bone resorption. Derived from monocyte macrophage hematopoietic lineage.

Osteoblasts

Large cell that can measure up to 30 um and are responsible for bone formation by synthesizing and secreting bone matrix.