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53 Cards in this Set
- Front
- Back
What is the first line of defense in the body?
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-skin and mucous membranes or respiratory, digestive, urinary, and reproductive systems
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What are the second line of defense in the body?
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-phagocytosis, complement, interferon, inflammation, fever
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What is the third line of defense in the body?
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-lymphocytes, antibodies
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How are microbes removed from the skin?
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-everytime movement occurs, thousands of dead skin cells are removed along with microorganisms
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What cells can phagocytize pathogens on the epidermis?
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-Langerhans cells (dendritic cells)
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What is collagen for?
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-found in the dermis
-gives skin strength and pliability to resist abrasions that could introduce microorganisms |
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How do the sweat glands play a role in nonspecific cases?
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-perspiration released
-salt inhibits growth of pathogen by drawing water from their cells -lysozyme destroys cell wall of bacteria |
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How do the oil glands play a role in nonspecific cases?
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-sebum secreted by sebaceous (iol) glands
-helps keep skin pliable and less likely to break or tear -lowers the pH of the skin to a level inhibitory to many bacteria |
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What is microbial antagonism?
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-competing of normal flora with potential pathogens making it difficult for them to prosper
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What are some various activities of normal flora that interupts pathogens?
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-secrete antimicrobial substances limiting pathogen growth
-consumption of nutrients -changes environment pH -helps stimulate body's second line of defense -promote overall health by providing vitamins to host |
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Where are some body areas that produce antimicrobial secretions?
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-stomach acid
-bile -urine -saliva |
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How is the eye protected?
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-lacrimal glands secrete tears that bathe the eye
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What are involved in blood defenses?
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-cells (phagocytosis)
-antimicrobial chemicals (interferons) -processes (inflammation, fever) |
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Does plasma or serum contain clotting proteins?
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-plasma (serum is liquid only)
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What cells exist in blood?
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-formed elements: erythrocytes, platelets, and leukocytes
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What are two types of macrophages?
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-wandering macrophages
-fixed macrophages |
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What are wandering macrophages?
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-leave the blood via diapedesis and phagocytize throughout the body
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What are fixed macrophages?
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-do not move throughout the body and often phagocytize within a specific organ
*Langerhans cells, alveolar macrophages, microglia, Kupffer cells |
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What is included in the reticuloendothelial system?
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-all macrophages, plus monocytes attached to endothelial cells
*AKA mononuclear phagocytic system |
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What are components of "innate immunity"?
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-phagocytosis
-extracellular killing by leukocytes (complement and interferons) -inflammation -fever |
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What are the five stages of phagocytosis?
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1) chemotaxis of phagocyte to microbe
2) adherence 3) ingestion of microbe by phagocytes 4) digestion of microbe by enzymes 5) elimination (exocytosis) |
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What blood cells are involved in extracellular killing?
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-eosinophils
-natural killer lymphocytes |
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Describe eosinophils.
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-mainly attack parasitic helminths (worms) by attaching to their surface
-secrete toxins that weaken or kill the helminth -high levels indicative of helminth infection |
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Describe Natural killer cells.
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-secrete toxins onto surface of virally infected cells and tumors
-differentiate normal body cells because of similar membrane proteins to NK cells |
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What are two ways to activate the complement system?
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-classical pathway; augments antibodies
-alternate pathway; before antibodies are made |
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What happens during complement activation?
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-forms membrane attack complex (MAC), which forms holes in membranes leading to lysis of pathogen
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What makes up the complement system?
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-serum proteins
-numbered acording to their discovery |
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What are the three end results of the complement cascade?
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-opsonization
-inflammation -membrane attack complex and cell lysis |
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What are the steps of the complement system (not last step though)?
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1) C1 activates when binding to antibody-antigen complexes
2) enzyme C1 splits C2 and C4 3) C2 and C4 fragments combine forming enzyme which splits C3 into C3a and C3b 4) C3b combines with remaining C2 and C4 to form another enzyme that cleaves C5 into C5a and C5b |
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What is the last step of the complement system?
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5) C5b combines with C6, C7, and several C9 molecules to form a MAC. This drills circular holes in the pathogens cytoplasmic membrane leading to hypotonic lysis of cell
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What does C3a do?
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-causes chemotoxis and inflammation
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What does C3b do (besides combining with other fragments)?
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-acts as opsonin
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What does C5a do?
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-causes chemotaxis and inflammation
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What are interferons?
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-protein molecules released by host cells to nonspecifically inhibit the spread of viral infections, particularly viruses with RNA genomes
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What are the three types of interferons?
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IFN-alpha
IFN-beta IFN-gamma (y) |
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When are IFN-y present?
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-appears later in the course of infection
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When are IFN-a and IFN-B present?
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-present early in the infection
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What is interferon therapy?
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-it was thought that this might be a good antiviral treatment
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What is the problem with the interferon therapy?
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-many viral infections don't respond to interferon therapy at all
-only a slight effect is seen with those viral infections that do respond |
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Describe how interferons work.
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-virus infects cell
-cell produces interferon to neighboring cells and bind to receptors which triggers AVP -AVP remains inactive in neighboring cell, but activates when double-stranded RNA enters and then attacks the RNA *original cell dead, but saved second cell |
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What are the characteristics of inflammation?
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-redness
-heat -swelling -pain |
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What is the effect of acute inflammation?
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-beneficial and short-lived
-dilation and increased permeability of blood vessel -migration of phagocytes |
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What is the effect of chronic inflammation?
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-develops slowly and lasts a long time
-can cause damage to tissues |
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How does inflammation occur (list up to blood clot)?
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-cut/injury
-damaged cells release histamine, protstaglandins, and leukotrienes -vessels more permeable, histidine causes vasodilation -macrophages and neutrophils squeeze through wall -blood clot forms |
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Once a blood clot forms during inflammation, what happens next?
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-more phagocytes migrate to site
-accumulation of damaged tissue forms pus -undifferentiated stem cells repair damaged tissue -blood clot absorbed or falls off as scab |
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What does increased permeability do during inflammation?
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-allows antimicrobial chemicals and clottin gproteins to seep into damaged tissue but also results in swelling, pressure on nerve endings, and pain
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What are pyrogens?
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-chemicals that trigger hypothalamus to increase the body's core temperature over 37 degrees
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What are the different types of pyrogens?
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-bacterial toxins
-antibody-antigen complexes -Interleukin-I (IL-1) |
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What are the benefits of fever?
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-enhances effects of interferons
-inhibits growth of some microorganims -may enhance performance of pahocytes, cells of specific immunity, and the process of tissue repair |
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What does IL-1 cause?
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-causes hypothalamus to secrete prostaglandins that reset the hypothalamic "thermostat"
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How does IL-1 work?
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-travels to hypothalamus
-hypo secretes prostaglandin which resets hypothalamic thermostat -nerve impulses cause shivering, high met rate, sweating inhib, and vasocon. -increased body temp to point set by hypothalamic thermostat |
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What are chills associated to fever due to?
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-reduced blood flow of constricted vessels
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What does a decrease in IL-1 cuase?
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-return of normal temperature of body
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