Microbiology Fundamentals A Clinical Approach, 2nd ed. by Cowan Chapter 12.

Microbiology Fundamentals: A Clinical Approach, 2nd ed. by Cowan Chapter 12 Host defense mechanisms Correct Answer- Multilevel network of innate, nonspecific protections and specific immunities First line of defense Correct Answer- Protective barrier (skin & mucous membranes) Any barrier that blocks invasion at the portal of entry Limits access to the internal tissues of the body Not considered a true immune response because it does not involve recognition of foreign substances, is very general in action Three types of barriers: physical, chemical, genetic Second line of defense Correct Answer- Eater cells (NK cells & macrophages) - innate immunity Internalized system of protective cells & fluids Includes inflammation and phagocytosis Acts rapidly at both the local and systemic levels once the first line of defense has been circumvented Generalized and nonspecific defenses that support and interact with specific immune responses: phagocytosis, inflammation, antimicrobial proteins, fever Third line of defense Correct Answer- Smart cells (antibodies, B-cells, & T-cells) - learned immunity Acquired on an individual basis as each foreign substance is encountered by lymphocytes The reaction with each different microbe produces unique protective substances Provides long-term immunity Skin Correct Answer- Stratum corneum: tough outer layer that is impervious and waterproof Constant sloughing of the outer layers of skin removes microbes Hair shaft is periodically shed and follicle cells are desquamated Flushing effect of swear removes microbes Mucous membranes Correct Answer- Digestive, urinary, and respiratory tracts, and of the eye Mucous coat impedes entry and attachment of bacteria Blinking and tear production flush the eye's surface Constant flow of saliva carries microbes to the stomach Vomiting and defecation evacuate noxious substances from the body Respiratory tract Correct Answer- Nasal hair traps larger particles Copious flow of mucus and fluids provides flushing action Ciliated epithelium conveys particles trapped in mucus toward the pharynx Sneeze reflex expels a large amount of air at high velocity