Chapter 43 - CR97-03

Chapter 43 - CR97-03 - Chapter 43 The Immune System 1 of 21...

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Chapter 43 Chapter 43 The Immune System 1 of 21 of 21
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Overview: Reconnaissance, Recognition, Overview: Reconnaissance, Recognition, and Response and Response Two major kinds of defense have evolved that counter the many dangerous pathogens it may encounter in the Innate immunity is present before any exposure to pathogens and is effective from the time of birth Involves nonspecific responses to pathogens Acquired immunity , also called adaptive immunity develops only after exposure to inducing agents such as microbes, toxins, or other foreign substances Involves a very specific response to pathogens 3 m Figure 43.1 2 of 21 of 21
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A summary of innate and acquired immunity INNATE IMMUNITY Rapid responses to a broad range of microbes ACQUIRED IMMUNITY Slower responses to specific microbes External defenses Internal defenses Skin Mucous membranes Secretions Phagocytic cells Antimicrobial proteins Inflammatory response Natural killer cells Humoral response (antibodies) Cell-mediated response (cytotoxic lymphocytes) Invading microbes (pathogens) Figure 43.2 3 of 21 of 21
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43.1: Innate immunity provides broad 43.1: Innate immunity provides broad defenses against infection defenses against infection External Defenses : Intact skin and mucous membranes form physical barriers that bar the entry of microorganisms and viruses Certain cells of the mucous membranes produce mucus , a viscous fluid that traps microbes and other particles In the trachea, ciliated epithelial cells sweep mucus and any entrapped microbes upward, preventing the microbes from entering the lungs Secretions from the skin give the skin a pH between 3 and 5 and also include proteins such as lysozyme 10 m Figure 43.3 4 of 21 of 21
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Internal Cellular and Chemical Defenses Depend mainly on phagocytosis Phagocytes , types of white blood cells, ingest invading microorganisms and initiate the inflammatory response Phagocytes attach to their prey via surface receptors and engulf them, forming a vacuole that fuses with a lysosome (SEE figure 43.4) Macrophages , a specific type of phagocyte, can be found either migrating through the body or residing in various organs of the lymph system In the lymph system, pathogens are brought to lymph nodes, which have high concentrations of phagocytes Natural killer (NK) cells trigger apoptosis in infected/cancerous body cells Microbes MACROPHAGE Vacuole Lysosome containing enzymes 1 2 3 4 5 6 Figure 43.4 5 of 21 of 21
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Antimicrobial Proteins Numerous proteins function in innate defense by attacking microbes directly of by impeding their reproduction About 30 proteins make up the complement system which can cause lysis of invading cells and help trigger inflammation Interferons provide innate defense against viruses and help activate macrophages Inflammatory Response (SEE figure 43.6) Histamine and other chemicals released from injured cells promote changes in blood vessels that
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This note was uploaded on 04/07/2008 for the course BIO 103 taught by Professor Mannino during the Fall '08 term at Long Island U..

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Chapter 43 - CR97-03 - Chapter 43 The Immune System 1 of 21...

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