Leukocytes Quiz

Overview of Leukocytes and their Types

• Leukocytes develop from pluripotential stem cells in the bone marrow.
• Hematopoietic growth factors influence stem cells to mature into terminally differentiated cells.
• Leukocytes circulate for only a few hours in the peripheral blood before migrating to tissues.
• Leukocytes defend the body against foreign invaders and are attracted to sites of inflammation, infection, or tissue injury by chemoattractants.
• There are three main types of hematopoietic cells: stem cells, progenitor cells, and precursor cells.
• Myeloblasts differentiate into promyelocytes, myelocytes, metamyelocytes, and finally, neutrophils.
• The five types of human leukocytes are neutrophils, lymphocytes, monocytes, eosinophils, and basophils.
• Neutrophils constitute 40-60% of circulatory leukocytes and have a segmented nucleus with two to four lobes.
• Eosinophils spend very little time in peripheral blood before migrating to tissues and are associated with allergic reactions, parasite infection, and chronic inflammation.
• Basophils constitute less than 1% of total leukocytes, have a bilobed nucleus, and large purple-black granules containing histamine and heparin.
• Monocytes are the largest cells in peripheral blood and function as phagocytes, ingesting and killing microorganisms.
• Lymphocytes are classified as T and B lymphocytes and are responsible for cell-mediated and humoral immunity, respectively.