White Blood Cells

White Blood Cells

• Are spherical cells that lack hemoglobin

• Form a thin, white layer of cells between plasma and red blood cells when the components of blood are separated from each other

Two functions of white blood cells

1. To protect the body against invading microorganisms

2. To remove dead cells and debris from the tissues by phagocytosis

A. Granulocytes- those containing large cytoplasmic granules

1. Neutrophil2. Basophil3. Eosinophil

B. Agranulocytes- those with very small granules that cannot be seen easily with the light microscope

1. Lymphocyte2. Monocyte

White blood cells are classified into two groups:

Neutrophils• The most common type

of white blood cells• Usually remain the blood

for a short time (10-12 hours)

• Move into other tissues, phagocytize microorganisms and other foreign substances

Basophils• Least common of all

white blood cells• Release histamine and

other chemicals that promote inflammation

• Also release heparin, which prevents the formation of clots

Eosinophils

• Involved in inflammatory responses associated with allergies and asthma

• Also involved in destroying certain worm parasites

Lymphocytes• Are the smallest of the

white blood cells• Their diverse activities

include the following:• Production of antibodies and

other chemicals that destroy microorganisms, contribute to allergic reactions, reject grafts, control tumors, and regulate the immune system.

Monocytes

• Are the largest of the white blood cells

• After they leave the blood and enter tissues, they enlarge and become macrophages, which phagocytize bacteria, dead cells, cell fragments, and any other debris within the tissues.