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Innate Immune

MIC 205 Exam 3

Our bodies protect themselves with three lines of defense. What are they? Innate, non-specific defenses (1st and 2nd lines of defense) and Adapted, specific defenses (3rd line of defense)
What are the general characteristics of the non-specific immune response? general defenses, response is the same to all stimuli, always present in healthy people, appear rapidly, short term protection (no memory), triggers adaptive, specific response
Which responses are considered first line defenses? dry skin flaking off and taking bacteria with it; cilia in respiratory tract trap and move bacteria so they can’t colonize; chemical barriers, normal bacterial flora
Which responses are considered second line defenses? phagocytosis by macrophages, neutrophils, and dendritic cells
Name several anatomical barriers that help compose the non-specific immune response. skin, mucous, hair, cilia, body fluids, dendritic cells, chemical barriers, normal bacterial flora,
Explain how the skin and mucous membranes form both physical and chemical barriers (sebum) against microorganisms. skin flakes off taking bacteria with it; sebum is a waxy substance on the skin that lowers pH
What are lysozymes and how do they protect the body against pathogens? enzymes that are destructive of bacteria; acts as an antiseptic
What body fluids contain lysozymes? tears, saliva, perspiration, nasal secretions
What is the role of pH in defending against pathogens? low pH is acidic which kills most pathogens
Define dermicidins. broad-spectrum antimicrobials that are active against many Gram-negative and Gram-positive bacteria and fungi; secreted by sweat glands
Define defensins. also called antimicrobial peptides; chains of about 40 amino acids that act against microorganisms
How does the normal flora colonizing our bodies protect us? competes with pathogens for nutrients, stimulates immune response, secretes bacteriocins
What are the steps of phagocytosis? chemotaxis, adherence, ingestion, digestion, and elimination
What happens in chemotaxis? movement of cell toward a chemical stimulus with the use of pseudopodia toward microorganisms at the site of an infection
What happens in adherence? phagocytes attach to microoganisms through the binding of complementary chemicals such as glycoproteins found on the membranes of cells
What happens in ingestion? pseudopodia are extended, surround microbe; microbe is internalized as the pseudopodia fuse to form a phagosome (food vesicle)
What happens in digestion? lysosomes fuse with phagosomes to form phagolysosomes (digestive vesicles), and digest or kill cell
What happens in elimination? phagocytes eliminate remains of microorganisms via exocytosis
How do some bacteria defend themselves against phagocytosis? capsules, leukocidins, some bacteria can live and reproduce in white cells
Give some examples of cells that are capable of phagocytosis. macrophages, neutrophils, dendritic cells
Name three cells that participate in general, extracellular killing of pathogens and explain how they protect us. Eosinophils attach to helminthes and secrete toxins that kill worms; neutrophils produce enzymes that kkill microorganisms and induce inflammation; natural kill lymphocytes secrete perforins and granzyme that kill pathogens
What is a Natural Killer (NK) Cell? type of defensive leukocyte of innate immunity that secretes toxins onto the surfaces of virally infected cells and neoplasms
How do NK cells kill target cells? kill by releasing perforins that penetrate the target cell and granzymes that cause programmed cell death
What kinds of cells are usually killed by NK cells? cancer cells and virus infected cells
What is complement? a set of serum proteins designated numerically according to the order of their discovery
What is the difference between the two main complement pathways? Which is the most efficient? Classic Pathway attaches to antigen-antibody; Alternate Pathway attaches directly to organism. Classic Pathway is most efficient
How does complement work? proteins initially act as opsonins and chemotactic factors, and indirectly trigger inflammation and fever; end result is lysis of foreign cells
What is opsonization? the coating process of complement
What is the role of complement in inflammation? In inflammation, complement causes an increase in histamine release which increases blood vessel dilation (the more histamine released the greater the inflammatory response).
Is inflammation beneficial? yes; dilates and increases permeability of blood vessels; facilitates migration of phagocytes; repairs injured tissues
What are the signs of inflammation? redness, pain, heat, swelling, loss of function
Explain the process of inflammation. Damaged tissue, WBCs, basophils and platelets produce histamine and cytokines. Cytokines call more WBCs to area. Histamines cause blood vessels to dilate. Blood moves to injured area (making it hot and red). Diapedesis.
What causes the blood vessels to dilate? histamines
What happens when the blood vessels dilate? blood moves to injured area—makes area hot and red
What is pus? whitish-yellow liquid formed at the site of inflammation during infection
Is inflammation a localized or systemic response? localized
Is fever beneficial? yes; increases number of T cells; decreases iron available for bacteria (bacteria need iron—competition for iron when fever is present); tissue repair; temp too high for some organisms to grow
Is fever localized or systemic? systemic
Explain what happens when a fever occurs. phagocytes produce pyrogens that stimulate the hypothalamus to release prostaglandins that reset the body temp thermostat higher; nerve impulses cause shivering, increased metabolic rate, sweating, vasoconstriction
What are interferons? protein molecules that inhibit the spread of viral infections
How does gamma interferon differ from alpha and beta interferon? Gamma interferon produced by T cells and NK cells; alpha and beta interferons are produced by viral infected cells
How do interferons protect host cells from viral infection? interfere with viral replication
What is the role of complement in cytolysis? In cytolysis, complement fragments attack foreign cell membranes, making holes in membranes, causing contents of cell to leak out, destroying cell.
Created by: slarmentrout