The Immune System - Chapter 20 Notes
Chapter 20: The Immune System
The immune system has two intrinsic systems:
1. Innate (nonspecific) defense system
2. Adaptive (specific) defense system
The immune system is a functional system rather than structural; there are no specific immune system organs
Pathogen: a disease-causing agent; anything foreign in our body that causes disease
Three lines of defense:
1st: external barriers
2nd: several non-specific defense mechanisms
3rd: immunity, specific resistance to disease
I. Innate Defenses (pp. 691–700) A. 1st line of defense - Surface Barriers: Skin and Mucosae • Protective chemicals inhibit or destroy microorganisms • Skin, a highly keratinized epithelial membrane, represents a physical barrier to most microorganisms and their enzymes and toxins (skin acidity = acid mantle) • Mucous membranes line all body cavities open to the exterior and function as an additional physical barrier. • Secretions of the epithelial tissues include acidic secretions (HCl, hydrochloric and protein-digesting enzymes of stomach mucosae), lipids in sebum, dermcidin in sweat, lysosome of saliva, lacrimal fluid in tears, and mucus (produced by goblet cells of mucous membranes). • Respiratory system modifications: mucus-coated hairs in the nose; cilia of upper respiratory tract sweep dust-and-bacteria-laden mucus from lower respiratory passages B. 2nd line of defense - Internal Defenses: Cells and Chemicals The second line of defense is necessary if microbes invade deeper tissues 1. Phagocytes (giant eating cells) confront microorganisms that breach the external barriers. • Mechanisms of phagocytosis: Adherence of phagocyte to pathogen … facilitated by opsonization (coating of pathogen by complement proteins or antibodies); and destruction of pathogens (acidification and digestion by lsysosomal enzymes; respiratory burst with the release of cell-killing free radicals and activation
The immune system has two intrinsic systems:
1. Innate (nonspecific) defense system
2. Adaptive (specific) defense system
The immune system is a functional system rather than structural; there are no specific immune system organs
Pathogen: a disease-causing agent; anything foreign in our body that causes disease
Three lines of defense:
1st: external barriers
2nd: several non-specific defense mechanisms
3rd: immunity, specific resistance to disease
I. Innate Defenses (pp. 691–700) A. 1st line of defense - Surface Barriers: Skin and Mucosae • Protective chemicals inhibit or destroy microorganisms • Skin, a highly keratinized epithelial membrane, represents a physical barrier to most microorganisms and their enzymes and toxins (skin acidity = acid mantle) • Mucous membranes line all body cavities open to the exterior and function as an additional physical barrier. • Secretions of the epithelial tissues include acidic secretions (HCl, hydrochloric and protein-digesting enzymes of stomach mucosae), lipids in sebum, dermcidin in sweat, lysosome of saliva, lacrimal fluid in tears, and mucus (produced by goblet cells of mucous membranes). • Respiratory system modifications: mucus-coated hairs in the nose; cilia of upper respiratory tract sweep dust-and-bacteria-laden mucus from lower respiratory passages B. 2nd line of defense - Internal Defenses: Cells and Chemicals The second line of defense is necessary if microbes invade deeper tissues 1. Phagocytes (giant eating cells) confront microorganisms that breach the external barriers. • Mechanisms of phagocytosis: Adherence of phagocyte to pathogen … facilitated by opsonization (coating of pathogen by complement proteins or antibodies); and destruction of pathogens (acidification and digestion by lsysosomal enzymes; respiratory burst with the release of cell-killing free radicals and activation