Details

Autor(en) / Beteiligte

• Farrell, A.P.

Titel

BLOOD | Cellular Composition of the Blood

Ist Teil von

• Encyclopedia of Fish Physiology, 2011, p.984-991

Ort / Verlag

Elsevier Inc

Erscheinungsjahr

2011

Link zum Volltext

Beschreibungen/Notizen

• Blood is a tissue contained within the circulatory system. It has three major components: red blood cells (RBCs, erythrocytes), white blood cells (WBCs, leukocytes), and the extracellular space around these cells, the plasma. Blood is primarily a transport medium that serves many functions. Its cellular composition of blood is regulated, dynamic, and multifunctional. The two primary blood cell types can be separated based on differences in cellular density, with hematocrit (Hct) and leucocrit (Lct) referring to the percentages of packed cells occupied by RBCs and WBCs, respectively. Fish RBCs are ovoid, nucleated, and primarily function in gas transport because of their high cellular content of the oxygen-binding protein hemoglobin. Blood viscosity increases with Hct and most fish have an Hct between 10% and 40%. The four major types of WBCs have primary roles in cellular defense and immunity; Iymphocytes and thrombocytes dominate over granulocytes, whereas monocytes are rare.