SG18 - MIBO 3000: Chapter 18 Study Guide Host Defenses...

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MIBO 3000: Chapter 18 Study Guide Host Defenses Against Microbial Infection Host Defenses: Normal Flora List 4 contributions of normal flora to your body: How is coadaptation related to normal flora and their human hosts? Normal flora can occasionally cause disease o This happens when pathogens get to areas where they “don’t belong” o For example, a splinter allows external pathogens to enter the body o Other normal flora can become serious pathogens when their normal niche conditions change to allow them to grow to a greater-than-normal degree Example: Antibiotic diarrhea Microbial Growth Microbial growth is most concentrated on “outside” surfaces of the body containing epithelial cells o These areas include, but are not limited to: skin, the GI tract, and esophagus o What is the MOST heavily colonized area of the body? Other areas of the body, however, are completely sterile (in healthy individuals) o These areas include: deep tissues, deeper lung areas (like the alveoli), the bladder, and uterus Types of Host Defenses There are two types of host defenses: o Constitutive defenses (or innate/nonspecific immunity) o Inducible defenses (or adaptive/specific immunity) What is the difference between these two types of defenses? Nonspecific Immune System Defenses 1. Microbial barriers a. Normal flora compete for space, nutrients 2. Mechanical barriers a. Skin: constantly sloughing off (taking microbes with it) b. Mucous membranes: produce mucous that continuously moves microbes away from particular areas
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c. Activities (like movement of fluid): i. Mediated by cilia in the respiratory tract or ii. Muscle movement in the esophagus and other areas of the body 3. Sequestering nutrients important to microbes a. Free iron (Fe) is EXTREMELY important for microbial biochemical pathways i. This means that microbes are constantly “scouting out” for iron b. Our bodies do two things to prevent microbes from having limitless access to iron: i. Transferrin is a molecule present in our bodies that binds to free iron in the environment and prevents microbes from gaining access to it ii. Our bodies can also house iron within our cells 1. However, some microbes have the ability to lyse host cells to gain access to the free iron contained within them 2. These microbes use the enzyme hemolysin to lyse red blood cells which naturally contain a lot of iron within heme molecules 4. Secretion of antimicrobial proteins
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This note was uploaded on 09/10/2011 for the course MIBO 3000 taught by Professor Shearer during the Spring '11 term at University of Georgia Athens.

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SG18 - MIBO 3000: Chapter 18 Study Guide Host Defenses...

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