Chapter 40 Immunity

Chapter 40 Immunity - Chapter 40 Immunity I. Nonspecific...

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Chapter 40 Immunity I. Nonspecific Defense Responses A. Barriers to Invasion [of pathogens] 1 Intact skin is an important barrier. 2 Ciliated, mucous membranes in the respiratory tract sweep out bacteria and particles. 3 Exocrine glands secrete lysozymes, which degrade the bacterial cell wall. 4 Gastric fluid in the stomach kills many pathogens. 5 The normal microbial inhabitants of the skin, gut, and vagina keep the growth of pathogens in check. B. Phagocytes: The Macrophages and Their Kin 1 White blood cells (neutrophils, eosinophils, monocytes = macrophages) engulf and destroy invading agents. 2 Phagocytes are distributed in blood, tissue spaces, lymph nodes, spleen, and other organs. C. Complement System 1 The complement system is a set of plasma proteins that enhance nonspecific and specific defense responses. 2 These proteins are activated in a cascading fashion when barriers to fungal and microbial infection are breached; the results are as follows: a. Chemical gradients of proteins attract phagocytes to the scene. b. Complement proteins coat the surface of invading cells—attracting phagocytes. c. Other proteins cause the pathogen to lyse and die. D. Inflammation 1 While complement proteins are being activated, basophils and mast cells secrete histamine, which promotes leakage of fluid out of capillaries. 2 Inflammatory response results include: a. Localized warming and redness occur at the site of damage or invasion. b. Fluid seeps from blood vessels causing swelling and delivery of infection-fighting proteins to the tissues. c. Phagocytes engulf foreign invaders and debris. d. Clotting mechanisms help wall off the pathogen and promote repair of tissues. II. Specific Defense Responses: The Immune System A. Introduction 1 Phagocytes summoned to an inflammation site are indiscriminate engulfers and may not be enough to check the spread of an invader. 2 Macrophages and T and B lymphocytes of the vertebrate immune system may be needed.
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Chapter 40 Immunity - Chapter 40 Immunity I. Nonspecific...

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