White Blood Cells and Formed Elements

Vocabulary flashcards identifying different types of white blood cells, red blood cells, and platelets from peripheral blood smears.

Monocyte

An agranular white blood cell that differentiates into macrophages and dendritic cells in tissues to perform phagocytosis and antigen presentation.

2% to 8%

Uncommon

Chronic infections, dead tissue, and foreign debris

Tuberculosis, Mono, chronic inflammation, tissue cleanup

Platelets

Small cell fragments in the blood that function in clotting, identified as tiny structures near red blood cells (RBC). They activate upon blood vessel damage to form clots, responding during vascular injury, tissue trauma, and systemic inflammatory responses like sepsis.

Basophil

A granular leukocyte dense with prominent dark purple granules that obscure the underlying nucleus. HISTAMINE/ HEPHREN

INFLAMMATION

Extremely Rare (often reads as 0 on a normal test)

Large allergens or blood-borne parasites

Asthma, anaphylaxis, hay fever, tick bites, early parasite defense

RBC (Red Blood Cell)

Anucleate biconcave blood cell responsible for oxygen transport, surrounding leukocytes and platelets across blood tissue preparations.

Lymphocyte

A type of agranular leukocyte with a large, round nucleus filling most of the cell, depicted near red blood cells and platelets. Viral infection

20% to 40% [1]

Very Common

Viruses, intracellular bacteria, or abnormal cells

Flu, Mono, COVID-19, Tuberculosis, Lymphoma, Autoimmunity

Neutrophil

A granular leukocyte containing a characteristically multi-lobed nucleus, visible in peripheral blood smears. Acute bacteria infection

50% to 70% [1]

Most Common

Free-floating bacteria, fungi, or dead tissue

Strep, Staph, pneumonia, appendicitis, heart attacks, burns

Eosinophil

A granular leukocyte containing prominent reddish-orange granules and a two-lobed nucleus, depicted alongside red blood cells (RBC). Parasitic

Quite Rare

Antibody-coated parasites or chronic tissue allergens

Parasitic worms, eosinophilic asthma, EoE, severe drug rashes