NonSpecific Resistance

Lecture 13 [Notes]

Nonspecific resistance refers to bodily defenses that protect us from almost any kind of 
pathogen. Contributors to nonspecific resistance are the skin and mucous membranes,
phagocytosis, inflammation, fever and the production of antimicrobial substances
other than antibodies. I. Mechanical and Chemical Barriers A. Intact skin & mucous membranes - prevent penetration B. Mucus and cilia - sweep materials from nose and throat C. Tears, Saliva, Urine, Vaginal Secretions - all move materials out of the body in a cleansing action D. Sebum, Lysozyme E. pH 1. Stomach acid 2. bile, duodenal enzymes 3. acidity of vaginal tract F. Interferon - nonspecific viral inhibitor II. Phagocytosis carried out by white blood cells or derivatives of white blood cells such as modified Monocytes (Macrophages) PHAGOCYTOSIS / \ / \ MICROPHAGES MACROPHAGES especially neutrophils wandering macrophages; fixed | macrophage or histiocytes; | Mononuclear Phagocytic System | or Reticuloendothelial System | | phagocytic against microbes phagocytic against dead & dying during the initial phase of microbes and worn out red blood infection cell as infection subsides; also involved in cell-mediated immunity Generally the phagocytic cells are polymorphonucleated cells (PMN) such as neutrophils or agranulocytic monocytes. Macrophages (derived from monocytes) make up the MPS or RES and are specialized as WANDERING (macrophages of spleen, bone marrow, lymph nodes, brain, connective tissue and lungs) or FIXED (Kupffer cells of the liver) cells.
@NCI, NIH "Understanding the Immune System", Click on this link for image
III. Circulatory System Fluid portion of blood is called PLASMA and contains the formed elements (cells and cell fragments). Plasma with fibrin or clotting factors removed is called SERUM. FORMED ELEMENTS are the red blood cells (ERYTHROCYTES), white blood cells (LEUKOCYTES), and platelets (THROMBOCYTES). White blood cells are divided into two categories based on Wright's staining: A. Granulocytes - contain prominent lysosomal granules 1. Neutrophils - make up 60-65% in normal differential count; highly phagocytic; capable of diapedesis 2. Basophils- make up approximately 0-2% of normal differential; non phagocytic; involved in allergic reactions through the release of histamine, heparin, serotonin, leukotrienes 3. Eosinophils - make up approximately 0-4% of normal differential count; somewhat phagocytic; capable of diapedesis; increase in numbers during hypersensitivity reactions and parasitic infections; may be attracted by chemotactic agents released by basophils All three of the above are considered to be Polymorphonucleated cells (PMN). B. Agranulocytes - no obvious granules upon staining 1. Monocytes - make up 5-8% of normal differential; poorly phagocytic until stimulated - in the tissues the monocytes are converted into macrophages when stimulated; the largest and most long-lived WBC's 2. Lymphocytes - make up 25-30% of normal differential; non phagocytic; involved in antibody and T cell formation when stimulated IV. Lymphatic System consists of fluid, vessels, and organs; fluid is known as LYMPH and consists of water, plasma, proteins, electrolytes and white blood cells (Lymphocytes); Lymphocytes migrate between blood and lymph; entry to lymph from the blood is in the lymph nodes examples of lymphatic tissues and organs include: tonsils, adenoids, spleen, Peyer's Patches of the intestinal mesentery, appendix, lymph nodes V. Antimicrobial Substances from Animal Tissues and Fluids A. Complement - found in serum; family of proteins which lyse invading microbes when stimulated or activated; hemolytic when activated; work with various antibodies B. Lysozyme - found in tears, sweat, saliva, mucous secre- tions, white blood cells - lyse Gram + bacteria C. Interferon - released from virus infected cells; activa- tes adjacent cells and interferes with viral replication D. Spermine - found in seminal and pancreatic fluids; bac- tericidal for a variety of Gram + pathogens E. Sebum - produced in sebaceous glands; bactericidal and fungicidal; becomes active after puberty

Back to Homepage
Back to BIOL 2275 Start Page