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59 Cards in this Set
- Front
- Back
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What are the two host defenses?
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innate, nonspecific; acquired, specific
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Innate houses what two defenses?
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First: surface protection
Second: cellular and chemical system that comes into play right after infectious agents |
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Acquired houses what defense?
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Third: includes specific host defenses: B and T cells
-has memory cells ready to attack |
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What are the three first line of defenses?
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physical: skin- stratified
chemicals: sebum, mucous membranes genetic: mutations to make you more or less susceptible |
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What are the primary physical and chemical defense barriers?
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sebaceous glands (acidic), tears (lysozyme), mucus, saliva (lysozyme), cilia, stomach acid, intestinal enzymes, defecation, intact skin, sweat, wax
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What are resident microbiota?
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-it trains host defenses so that commensals are kept in check and pathogens are eliminated
-interruptions in this process may lead to immunologic disturbances in the gut |
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What is the immune system?
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large, complex, and diffuse network of cells and fluid that permeate every organ and tissue
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What body compartments participate in the immune system?
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-the retiuloendothelial system (RES)- phago/pino -cytic
-the extracellular fluid (ECF)- spaces surrounding tissue cells -the bloodstream -the lymphatic system |
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What does the network of connective tissue surrounding all organs?
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-provides a passageway within and b/w tissues and bodily tissues
-thymus, lymph nodes, tonsils, spleen, MALT/GALT |
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What are marcophages?
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many can attack foreign intruders- good at phagocytosis
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What is the circulatory system?
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body compartments are screened by circulating WBCs in the cardiovascular system
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What is the lymphatic system?
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consists of a branching network of vessels that extend into most body areas; lymph nodes spleen, GALT, thymus gland, tonsils
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What does the lymphatic system do?
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transport lymph through system of vessels and lymph nodes, leading to major vessels that drain back to the circulatory system
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What are the functions of the lymphatic system?
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-to return extracellular fluid to circulatory system
-house most immune responses |
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What does the thymus do?
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thymus cells develop specificity and are released into circulation as mature T cells
-T cells them migrate and settle in lymph nodes and spleen |
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What is the spleen for?
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-serves as a filter for blood
-primarily removes worn-out red blood cells -also filters pathogens from the blood for phagocytosis by macrophages- lymph nodes: filter lymph |
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Gut-associated lymphoid tissue (GALT)
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-discrete bundles of lymphocytes on or just beneath the intestinal mucosa
-provides an effective first strike potential against the constant influx of microbes in food -appendix |
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What are Peyer's patches? (GALT)
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aggregations of lymphocytes in the ileum of the small intestine
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What is the second line of defense for?
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-generalized and nonspecific defenses that support and interact with specific immune responses: phagocytosis, inflammation, fever, antimicrobial proteins
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What is phagocytosis?
What are professional? |
-cell eating- macrophages
-neutrophils: WBC nonspecific -monocytes:WBC turn into--> macrophages -macrophages: become specialized and differentiate |
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What is pathogen associated molecular patterns? (PAMPs)
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signal molecules found on microbial surfaces recognized by phagocytes and other defensive cells
-bacterial PAMPs: peptidoglycan and LPS -viral PAMPs: double-stranded RNA |
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What are pattern recognition receptors (PRRs)?
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-found on phagocytes, dendritic cells, endothelial cells and lymphocytes
-recognize and bind PAMPs |
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What are the steps to phagocytosis?
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1. chemotaxis, 2. adhesion, 3.&4. engulfment and phagosome formation, 5. phagolysosome formation and killing, 6. destruction, 7. elimination
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What is chemotaxis?
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phagocytes migrate into a region of inflammation with a deliberate sense of direction, attracted by a gradient of stimulant products from the parasite and host tissue at the site of injury
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What is adhesion?
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phagocytes use pattern recognition to identify and stick to foreign cells
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What is engulfment and phagosome formation?
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one phagocyte has made contact with its prey, it extends pseudo-pods that enclose the cells or particles in a pocket and internalize them in a vacuole called a phagosome
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What is phagolysosome formation and killing?
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lysosomes fuse with phagocytes; granules containing antimicrobial chemicals are released into the phagolysosome forming a potent brew designed to poison and then dismantle the ingested material
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What is destruction and elimination?
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destructive chemicals destroy the bacterial cells and then small bits of the debris are released from the macrophage by exocytosis
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What is rubor, calor, tumor, dolor?
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rubor: redness
calor: warmth tumor: swelling dolor: pain |
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What are the chief functions of inflammation?
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to mobilize and attract immune components to injury; start to repair tissue damage and localize and clear away harmful substances
-destroy microbes and block their further invasion |
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What are factors that elicit inflammation?
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-trauma from infection
-tissue injury of necrosis due to physical or chemical agents -specific immune reactions |
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Inflammation steps
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injury/immediate reactions; vascular reactions; edema and pus formation; resolution/scar formation
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What is Diapedesis and Chemotaxis of Leukocytes?
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diapedesis: migration of WBCs out of blood vessels into tissues
chemotaxis: the tendency of cells to migrate in response to a specific chemical stimulus given off at a site of injury or infection |
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What is a fever?
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an abnormally elevated body temperature-universal symptom of infection
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What is our temperature maintained by?
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the hypothalamus
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What are pyrogens?
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substances that reset the hypothalamic thermostat to a higher setting
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What are exogenous pyrogens?
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products of microbes such as viruses, bacteria, protozoans, fungi, endotoxin, vaccines
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What are endogenous pyrogens?
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liberated by monocytes, neutrophils, and macrophages during phagocytosis such as IL-1 (interleukin-1) and TNF (tumor necrosis factor)
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What are the benefits of fevers?
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-inhibits multiplication of temperature sensitive microorganisms
-impedes nutrition of bacteria by reducing the availability of iron -increases metabolism and stimulates immune reactions |
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What is an interferon (IFN)?
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a small protein produced naturally by certain white blood and tissue cells
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Are interferons more than just antivirals/what are they involved in?
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they are involved in defenses against microbes; involved in immune regulation and intercommunication
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What are interferon alpha and beta produced by?
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they are produced by lymphocytes, fibroblasts and macrophages
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What are interferon gamma produced by?
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produced by T cells
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What are the biological activities of interferon?
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bind cell surfaces and induce changes in genetic expression
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Three IFNs can inhibit what?
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the expression of cancer genes
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What do IFN alpha and beta stimulate?
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phagocytes
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What does IFN gamma do?
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it is the immune regulator of macrophages and B and T cells
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Describe the antiviral activity of interferon
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when a cell in infected by a virus (and sometimes other microbes), its nucleus is triggered to transcribe and translate the interferon gene. IFN diffuses out of the cell and bind to IFN receptors on nearby uninfected cells where it induces production of proteins that eliminate genes from foreign organisms
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What does the antimicrobial protein: complement consist of?
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it consists of 26 blood proteins that work in concert to destroy bacteria and certain viruses
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What is the cascade reaction?
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sequential physiological response
-has 3 different ways distinguished by how they are activated |
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What are the steps to a classical complement pathway at a single site?
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1. initiation: C1 components bind to antibodies
2. amplification and cascade: C1 leads to C5 being cleaved and bound to the membrane 3. polymerization: C5 product becomes site of assembly of an attack complex made of complement proteins 4. membrane attack: final product leads to cell lysis |
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What do humans and bacteria require for their enzymes?
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iron
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What does it become a factor in?
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becomes a rate-limiting factor in bacterial growth
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What are iron binding proteins?
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they keep available iron bound so tightly that it cannot be used by bacteria
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What are siderophores?
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they are proteins produced by bacteria capable of scavenge iron from iron-binding proteins
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What are antimicrobial peptides?
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short proteins 15-20 amino acids
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What are antimicrobial peptides able to do?
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able to insert themselves into prokaryotic membranes to kill microbes
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What are the three antimicrobial peptides?
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defensin, margainins, protegrins
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Describe the antimicrobial peptides?
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these peptides have various mechanisms, but a very common one is to insert into pathogen membranes using a positive charge plus a hydrophobic tail
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