BIO 274 1st Edition Exam 3 Study Guide Chapters 15 17 20 25 Chapter 15 second half Microbial Mechanisms of Pathogenicity Invasins surface proteins produced by microbes that rearrange nearby actin filaments Cadherin glycoprotein that bacteria use that bridges the junctions from cell to cell Microbes can damage host cells in 4 basic ways 1 Using the Host s Nutrient s Siderophores proteins secreted by pathogens to obtain free iron Released into medium by pathogen Take iron away from iron transport proteins by binding iron even more tightly 2 Direct Damage Pathogens metabolize multiply cells which causes them to rupture 3 The Production of Toxins Toxins poisonous substances that are produced by certain microbes Toxigenicity capacity of microbes to produce toxins Toxins can be transported by blood or lymph very dangerous Toxins can inhibit protein synthesis destroy blood cells blood vessels disrupt nervous system by causing spasms 2 Types of Toxins Exotoxins produced inside some bacteria as part of their growth metabolism are secreted by the bacterium into the surrounding medium o Proteins many are enzymes so they can be very harmful o Can easily diffuse into blood o Destroy parts of host s cells o Very specific o Among most lethal substances known o Body produces antibodies called antitoxins to fight o 3 types A B toxins made of polypeptides most common A part is the active enzyme component B part is binding component Membrane disrupting toxins cause lysis of host cells by disrupting their plasma membranes Superantigens provoke intense immune response bacterial proteins stimulate proliferation of immune cells called T cells that release huge amounts of cytokines small protein molecules These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Endotoxins part of the outer portion of the cell wall of gramnegative bacteria o Lipopolysaccharides o Released when gram negative bacteria die their cell wall undergoes lysis o Stimulate macrophages to release lots of cytokines which is very toxic o All endotoxins produce same signs symptoms o Cause small blood clots which clog capillaries cause tissue death disseminated intravascular coagulation DIC Shock any life threatening decrease in blood pressure Septic shock shock caused by bacteria Limulus Amebocyte Lysate LAL can detect even minute amounts of endotoxin R factors r means resistance plasmids Inclusion bodies granules found in cytoplasm or nucleus of some infected cells 1 Sometimes viral parts nucleic acids proteins 2 Vary in size shape staining properties 3 Presence can help identify the virus causing an infection Syncytium huge multinucleate cell formed by several adjacent infected cells fused together Interferons substances produced by virus infected cells Contact inhibition normal cells cease growing in vitro when they come close to another cell Trichothecenes fungal toxins that inhibit protein synthesis in eukaryotic cells 1 Cause headaches nausea vomiting etc In general a microbe uses the same portal for entry exit 1 Most common portals of exit respiratory and gastrointestinal tracts Respiratory coughing sneezing Gastrointestinal saliva feces Chapter 16 Innate Immunity Nonspecific Defenses of the Host 2 Types on Immunity o 1 Innate refers to defenses that are present at birth 1st line of defense skin mucous membranes 2nd line of defense NK cells phagocytes inflammation fever antimicrobial substances Innate immune responses show early warning sign Responds rapidly but no memory component Responses are activated by protein receptors in plasma membranes of defensive cells Toll like receptors TLRs are activators that attach to various component commonly found on pathogens called pathogenassociated molecular patterns PAMPs Cytokines proteins that regulate the intensity duration of immune responses recruit other cells macrophages dendritic cells to isolate destroy the microbes o 2 Adaptive based on a specific response to a specific microbe once a microbe has breached the innate immunity defenses Adapts to certain microbe Slower to respond has memory component Involves lymphocytes T cells B cells Physical Defense Factors o Skin largest organ in weight surface area 2 distinct portions 1 Dermis inner thicker portion connective tissue 2 Epidermis outer thinner portion many layers of continuous sheets of epithelial cellstight pack together o Top layer is dead made up of protective protein keratin o Fungi hydrolyze keratin in moist conditions o Endothelial cells epithelial cells that line blood lymphatic vessels aren t closely packed permits defensive cells to move from blood to tissues it permits microbes from moving into out of blood lymph o Mucous membranes consist of an epithelial layer underlying connective tissue layer Line entire gastrointestinal respiratory and genitourinary tracts Secretes mucus slightly viscous glycoprotein produced by goblet cells of a mucous membrane Prevents tract from drying out o Lacrimal apparatus drains tears Tears keep microbes from settling on eye surface o Saliva produced by salivary glands dilutes of microbes washes them form surface of teeth mouth o Cilia cells that cover the mucous membrane of the lower respiratory tract Propel inhaled dust microbes that have become trapped in mucus upward toward the throat which ciliary escalator Epiglottis small lid of cartilage covers the larynx voicebox during swallowing Chemical Defense Factors o Sebaceous oil glands of the skin produce an oily substance called sebum that prevents hair from drying becoming brittle Also forms a protective film over the surface of the skin Sebum is unsaturated fatty acids which inhibit growth of certain pathogenic bacteria fungi Skin is between pH 3 5 because of the fatty acids lactic acids Perspiration helps maintain body temp eliminate certain wastes flush microbes from the surface of the skin contains lysozymes enzyme capable of breaking down cell walls of gram positive bacteria gramnegative bacteria o pH acid of saliva 6 55 6 85 also inhibits some microbes also contains antibody that prevents attachment of microbes o Gastric juice produced by glands of the stomach Mix of HCl enzymes mucus pH 1 2 3 0 o Vaginal secretions glycogen produced by epithelial cells is broken down into lactic acid by Lactobacillus acidophilus creates an acid pH 3 5 that inhibits microbes has some antimicrobial activity Blood consists of fluid called plasma and