Notes

White blood cells are usually larger than RBC (8 - 20 µm), have a nucleus, and appear white (if not stained -- when stained, they appear bluish). • Much less numerous than RBC (only 7,000 to 8,000 cells per cubic millimeter). White blood cells, called leukocytes, are outnumbered by the red blood cells 600 to 1. There are two main types of Leukocytes: 1. Granulocytes: have granules in the cytoplasm and a many-lobed nucleus joined by nuclear threads (called "polymorphonuclear"). The granulocytes include Neutrophils (phagocytizes primarily bacteria), Eosinophils (phagocytizes and destroys antigen-antibody complexes), and Basophils (congregates in tissues, releases histamine when stimulated). Formed in the red bone marrow. The granules of a neutrophil are lysosomes. 2. Agranulocytes: Include Lymphocytes and Monocytes.
They don't have granules, and have a circular (lymphocytes) or indented (monocytes) nucleus. They are produced in lymphoid tissue found in the spleen, lymph nodes, and tonsils. Tye B lymphocytes produce antibodies in blood and lymph, Type T lymphocytes kill virus-containing cells. Monocytes become macrophages. • Infection fighting by white cells is primarily dependent on the neutrophils, which comprise 60 to 70% of all leukocytes, and the lymphocytes (which make up 25 to 30%). • Neutrophils, monocytes, and eosinophils are phagocytic. They engulf invaders at the site of infection. • Lymphocytes don't work this way. They secretea class of gamma globulins (proteins) called IMMUNOGLOBULINS (=ANTIBODIES), which combine with foreign substances to inactivate them. • Lymphocytes are the smallest white blood cells. When microbes invade the body
, lymphocytes begin to multiply and they become transformed plasma cells. Each microbe stimulates only one type of lymphocyte to multiply and form one type of plasma cell. The type of plasma cell formed is the type that can make a specific antibody to destroy the particular microbe that has invaded the body.
Red bone marrow continually produces white blood cells, except lymphocytes and monocytes, and keeps a reserve ready in case of need. Lymphocytes and monocytes are produced by lymphatic tissue located in the lymph nodes and spleen. When a parasite or virus invades and begins to colonize, the reserves of white blood cells are released and the manufacturing of large quantities of the appropriate white cells begins.
It is this increased production that causes fever. Because white blood cells are very specific for various illnesses, their count can help doctors diagnose patients
Germ theory- the belief that microorganism did not cause infections would not wash anything