Page 216 - Atlas of Histology with Functional Correlations

FORMED ELEMENTS: MAJOR BLOOD

CELL TYPES

Erythrocytes

Most numerous cells in blood
Erythrocytes are nonnucleated cells that remain in blood

Contain hemoglobin with iron molecules in the cytoplasm
Carry oxygen as oxyhemoglobin and carbon dioxide as
carbaminohemoglobin

Biconcave shape increases the surface area to carry respiratory gases
Life span is about 120 days, after which cells are phagocytosed in the spleen,
liver, and bone marrow

Platelets

Membrane-bound fragments of bone marrow megakaryocytes and are not
blood cells
Function in blood vessels to promote blood clotting when vessel wall is
damaged

In damaged vessels form a plug that increases with adhesive glycoproteins
and fibrin
Fibrin traps more platelets and blood cells and forms a blood clot

Cause clot retraction and pull damaged edges of the blood vessel together
Following vessel repair, the clot is removed by the proteolytic enzyme
plasmin

Leukocytes

Contain nuclei and are subdivided into granulocytes and agranulocytes
Granulocytes with cytoplasmic granules are neutrophils, eosinophils, and
basophils
Agranulocytes without cytoplasmic granules are monocytes and lymphocytes

Granulocytes

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