Characteristics and Functions of Leukocytes

A collection of vocabulary flashcards covering the classification, types, features, and functions of white blood cells (leukocytes) based on lecture notes.

Diapedesis

The process of a white blood cell oozing out of a blood vessel.

Leukocytes

The scientific term for white cells, derived from the word 'leukos' meaning white, which spend $90\%$ of their time in tissue fluid or lymph.

Granular WBCs

A category of white blood cells characterized by cytoplasm containing granules and nuclei usually constricted into lobes.

Non-granular WBCs

A category of white blood cells characterized by cytoplasm without granules and a single large nucleus.

Neutrophils

The most abundant granular WBC ($62\%$) featuring a nucleus with $3$-$4$ lobes, produced in the bone marrow to engulf bacteria via phagocytosis.

Eosinophils

Granular WBCs ($2.3\%$) with a $2$-lobed nucleus and granules that stain dark red with eosin (acid dye), associated with allergies and antitoxin secretion.

Basophils

Granular WBCs ($0$-$4\%$) with indistinctly lobed nuclei that stain with basic dyes like methylene blue and release histamine to dilate blood vessels during inflammation.

Lymphocytes

The smallest non-granular WBCs ($30\%$) possessing a single large nucleus, produced in the bone marrow and lymph glands (spleen, tonsils) to produce antibodies.

Monocytes

Non-granular WBCs ($5.3\%$) with a large kidney-shaped nucleus that transform into macrophages at infection sites to ingest germs.

Phagocytosis

A defensive mechanism where WBCs, particularly neutrophils, engulf particle-like solid substances such as bacteria.

Inflammation

A tissue reaction to injury or localized germ invasion characterized by increased local heat, redness, swelling, and pain.

Histamine

A chemical released by basophils during inflammation that causes the dilation of blood vessels.

Infection Indicator

An abnormal increase in the white blood cell count up to about $50,000$ or more per cubic $mm$.

Eosin

An acid dye used to stain the large cytoplasmic granules of eosinophils dark red.

Methylene blue

A basic dye used to stain the granules of basophils.