Ch 21 Lecture Notes a&P
Chapter 21 The Immune System:
Innate and Adaptive Body Defenses
Innate and Adaptive Defenses (Fig. 21.1, pg. 767)
Body Defenses against Infection (Fig. 21.1, pg. 767) * Immunity * Resistance to disease * Pathogen * disease causing agent * bacteria, viruses, etc
* Innate (nonspecific) Defenses * responds quickly * general defenses * protects against many pathogens * First line of defense * skin and mucosae prevent entry of microorganisms * Second line of defense * antimicrobial proteins, phagocytes, and other cells * Inhibit spread of invaders throughout the body * Inflammation is its most important mechanism * Adaptive (specific) Defenses * Third line of defense – mounts attack against specific foreign substances * Takes longer to react than the innate system * Works in conjunction with the innate system * carried out by lymphocytes that recognize a specific invader
* Both defenses work together to protect the body against infection
Innate (Nonspecific) Defenses * 1. First Line of Defense – Surface Barriers: skin and mucous membranes * Skin * Intact epidermis layer of the skin; tough physical barrier * Keratin is resistant to weak acids and bases, bacterial enzymes, and toxins * Mucosae (mucus membranes) provide similar mechanical barriers * Protective chemicals inhibit or destroy microorganisms * Sebum, which has a pH of 3 to 5 due to the presence of unsaturated fatty acids and lactic acid * Gastric juice renders the stomach nearly sterile because its low pH (1.5-3.0) kills many bacteria and destroys most of their toxins * Saliva and lacrimal fluid contain lysozyme that also has antimicrobial properties. * Mucus traps microorganisms that enter the digestive and respiratory systems * Respiratory system modifications * Mucus-coated hairs in the nose trap inhaled
Innate and Adaptive Body Defenses
Innate and Adaptive Defenses (Fig. 21.1, pg. 767)
Body Defenses against Infection (Fig. 21.1, pg. 767) * Immunity * Resistance to disease * Pathogen * disease causing agent * bacteria, viruses, etc
* Innate (nonspecific) Defenses * responds quickly * general defenses * protects against many pathogens * First line of defense * skin and mucosae prevent entry of microorganisms * Second line of defense * antimicrobial proteins, phagocytes, and other cells * Inhibit spread of invaders throughout the body * Inflammation is its most important mechanism * Adaptive (specific) Defenses * Third line of defense – mounts attack against specific foreign substances * Takes longer to react than the innate system * Works in conjunction with the innate system * carried out by lymphocytes that recognize a specific invader
* Both defenses work together to protect the body against infection
Innate (Nonspecific) Defenses * 1. First Line of Defense – Surface Barriers: skin and mucous membranes * Skin * Intact epidermis layer of the skin; tough physical barrier * Keratin is resistant to weak acids and bases, bacterial enzymes, and toxins * Mucosae (mucus membranes) provide similar mechanical barriers * Protective chemicals inhibit or destroy microorganisms * Sebum, which has a pH of 3 to 5 due to the presence of unsaturated fatty acids and lactic acid * Gastric juice renders the stomach nearly sterile because its low pH (1.5-3.0) kills many bacteria and destroys most of their toxins * Saliva and lacrimal fluid contain lysozyme that also has antimicrobial properties. * Mucus traps microorganisms that enter the digestive and respiratory systems * Respiratory system modifications * Mucus-coated hairs in the nose trap inhaled