<p>Chapter 20 Resistance and the Immune System: Innate Immunity</p><p>Chapter Summary and Essay Questions This chapter describes mechanisms used by the host to resist disease. The immune system is described as being composed of two interacting responses, the swift, nonspecific innate and the slower, but specific, adaptive. The cells, molecules and tissues involved in these immune responses are introduced. The rest of the chapter describes the innate response in more detail, including mechanical barriers and chemical defenses and how the pathogen is recognized. Included are descriptions of the phagocytosis process, inflammation, complement, and other effectors. On completing the chapter, you should be able to answer the following essay questions: a. Describe the major fluid and cellular components of the human circulatory system, especially as they relate to the lymphatic system and the defense against disease. b. Describe and compare the six types of leukocytes and how they function. c. Outline the basic components and functions of the lymph and the lymphatic system. d. Compare and state some specific examples of the broad types of nonspecific resistance. e. List the physical and chemical barriers of innate immunity and judge the role of each as a defense against infectious disease. f. Describe the process of phagocytosis, and assess its effectiveness as a second line of body defense against infection. g. Identify the four characteristic signs of inflammation, and describe how an inflammatory response develops from an infection. h. Explain how a fever can provide nonspecific resistance to disease. i. Summarize the role of natural killer (NK) cells in innate immunity. j. Construct a chart showing how complement acts to mark pathogens for destruction. k. Assess the role of pathogen-associated molecular patterns (PAMPs) and toll-like receptors and in innate immunity. l. Describe the role of interferon as a defense mechanism against virus infection.</p>