Chapter 36 Defenses Against Disease Lecture Outlines by Gregory Ahearn University of North Florida Copyright 2011 Pearson Education Inc Chapter 36 At a Glance 36 1 What Are the Mechanisms of Defense Against Disease 36 2 How Do Nonspecific Defenses Function 36 3 What Are the Key Components of the Adaptive Immune Response 36 7 How Does Medical Care Assist the Immune 36 8 What Happens When the Immune System Response Malfunctions 36 9 How Does the Immune System Combat Cancer Biology Life on Earth 9e Copyright 2011 Pearson Education Inc 36 1 What Are the Mechanisms of Defense Against Disease The world is teeming with microscopic living organisms called microbes which include bacteria protists and fungi and viruses which are not considered to be alive Most microbes live in water or the soil most that live in animal bodies do not harm them and may be beneficial When microbes cause disease they are called pathogens Most microbial diseases such as cholera measles plague tetanus and chicken pox have been with humans for thousands of years New more deadly strains of familiar pathogens are called emerging infectious diseases Biology Life on Earth 9e Copyright 2011 Pearson Education Inc 36 1 What Are the Mechanisms of Defense Against Disease Emerging infectious diseases Since the early 1980s several viruses have emerged as serious threats to human health including HIV Ebola virus West Nile virus SARS swine flu and bird flu One strain of the common intestinal bacterium E coli which is normally harmless can cause food poisoning Some Staphylococcus bacteria that normally cannot penetrate the skin will cause severe infections or fatal toxic shock syndrome when they enter the body Biology Life on Earth 9e Copyright 2011 Pearson Education Inc 36 1 What Are the Mechanisms of Defense Against Disease Vertebrate animals have three major lines of defense against disease Nonspecific external barriers Nonspecific internal defenses Specific internal defenses Figure 36 1 Biology Life on Earth 9e Copyright 2011 Pearson Education Inc 36 1 What Are the Mechanisms of Defense Against Disease Vertebrate animals have three major lines of defense against disease continued Nonspecific external barriers These barriers prevent most disease causing microbes from entering the body They are primarily anatomical structures such as skin and cilia and secretions such as tears saliva and mucus These barriers cover the external surfaces of the body and line the body cavities that come in contact with the external environment such as the surfaces of the respiratory digestive and urogenital tracts Biology Life on Earth 9e Copyright 2011 Pearson Education Inc 36 1 What Are the Mechanisms of Defense Against Disease Vertebrate animals have three major lines of defense against disease continued Nonspecific internal defenses If the external barriers are breached a variety of nonspecific internal defenses collectively called the innate immune response swing into action Components of this response include White blood cells which engulf foreign particles or destroy infected cells Chemicals released by damaged cells and proteins released by white blood cells that trigger inflammation and fever These responses operate regardless of the exact nature of the invader neutralizing the threat Biology Life on Earth 9e Copyright 2011 Pearson Education Inc 36 1 What Are the Mechanisms of Defense Against Disease Vertebrate animals have three major lines of defense against disease continued Specific internal defenses The final line of defense is the adaptive immune response in which immune cells selectively destroy specific invading microbes and toxins and then remember the invader This allows for a rapid response to the invader if it reappears in the future Biology Life on Earth 9e Copyright 2011 Pearson Education Inc 36 1 What Are the Mechanisms of Defense Against Disease Invertebrate animals possess the first two lines of defense Invertebrates lack adaptive immune responses and must rely on the two nonspecific defenses that include External skeletons Slimy secretions White blood cells that attack pathogens and secrete proteins to neutralize the invaders or the toxins they release Defensive proteins such as lysosome are similar in vertebrates and invertebrates suggesting a common ancestor among most of today s animal species Biology Life on Earth 9e Copyright 2011 Pearson Education Inc 36 2 How Do Nonspecific Defenses Function The ideal defenses are barriers that prevent invaders from entering the body in the first place If these barriers are breached however the body has several nonspecific methods of killing a wide variety of invading microbes Biology Life on Earth 9e Copyright 2011 Pearson Education Inc 36 2 How Do Nonspecific Defenses Function The skin and mucous membranes form external barriers to invasion The first line of defense consists of two surfaces with direct exposure to the environment The skin The mucous membranes of the digestive respiratory and urogenital tracts Biology Life on Earth 9e Copyright 2011 Pearson Education Inc 36 2 How Do Nonspecific Defenses Function The skin and its secretions block entry and provide an inhospitable environment for microbial growth The skin is a barrier to microbes The outer surface of the skin consists of dry dead cells filled with tough proteins that do not allow the microbes to obtain the water and nutrients they need to survive The secretions from sweat and sebaceous glands contain natural antibiotics such as lactic acid that inhibit the growth of many bacteria and fungi Biology Life on Earth 9e Copyright 2011 Pearson Education Inc 36 2 How Do Nonspecific Defenses Function Antimicrobial secretions mucus and ciliary action defend the mucous membranes against microbes Mucous membrane secretions trap microbes entering the nose or mouth They contain antibacterial proteins including lysozyme which kills bacteria by digesting their cell walls and defensin which makes holes in bacterial plasma membranes Cilia on the membranes sweep up the mucus so it is swallowed or coughed or sneezed out of the body Biology Life on Earth 9e Copyright 2011 Pearson Education Inc 36 2 How Do Nonspecific Defenses Function If the microbes are swallowed they enter the stomach where protein digesting enzymes and extreme acidity is lethal to them The intestines contain bacteria that while harmless to humans secrete substances that destroy invading bacteria or fungi In the urinary tract the slight acidity of urine inhibits
View Full Document
Unlocking...