Hematology Course: Introduction and Hematopoiesis

This set of vocabulary flashcards covers the fundamentals of hematopoiesis, stem cell biology, erythropoiesis regulation, and clinical hematological reactions such as left shifts and leukemoid reactions.

Hematopoiesis

A well controlled, continuous process of blood cell formation, production, differentiation, and development to replenish dying cells and respond to increased demands like bleeding or infection.

Haemopoietic Stem Cell (HSC)

A cell derived from a pluripotential stem cell that possesses the properties of self-renewal and differentiation into mature blood cells.

Stem Cell Factor (SCF)

A non-lineage specific regulator involved in the regulation of hematopoiesis.

Extramedullary hematopoiesis

The reactivation of hematopoietic islands in the liver and spleen (and other tissues) when the bone marrow is unable to meet demands, is infiltrated by malignant cells, or is replaced by fibrous tissue.

Normoblasts

Also known as erythroblasts or nucleated RBCs, these are immature red cells that are not present in normal human peripheral blood.

Reticulocyte

A non-nucleated red cell that still contains ribosomal material (RNA) in the cytoplasm; the normal range is $0.5\% - 2.0\%$ in adults and $2.5\% - 6.0\%$ in newborns.

Polychromasia

The morphological appearance of reticulocytes on a standard blood smear.

Erythropoietin (Epo)

A hormone that increases in response to anemia or hypoxia to stimulate red cell production by inhibitng hepcidin synthesis and increasing iron absorption.

Myeloblast

The first recognizable granulocyte precursor located in the bone marrow.

Granulocyte-Colony Stimulating Factor (G-CSF)

A lineage-specific growth factor that stimulates the proliferation, differentiation, and functional activation of neutrophils while suppressing apoptosis.

Left shift (Bandemia)

The morphological description of the release of immature granulocyte cells (mainly band forms) from the bone marrow to the peripheral blood, often due to infection or G-CSF administration.

Leukoerythroblastic reaction

The abnormal release of immature precursors of both red cell (erythroid) and white cell (myeloid) lines in the peripheral blood, indicating a significant disturbance of marrow function.

Neutrophilic leukocytosis

A condition defined by a total WBC count $> 11,000/mm^3$ ($11 \times 10^9/L$) or an absolute neutrophil count (ANC) $> 7,500/mm^3$ ($7.5 \times 10^9/L$).

Leukemoid reaction

An excessive, benign reactive leukocytosis with a WBC count up to $50,000/mm^3$ ($50 \times 10^9/L$) and a significant increase in immature precursors.