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Flashcards in Innate immunity Deck (50):
1

immunity

body's ability to resist disease

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innate

non specific

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adaptive

acquired and specific

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innate resistance to infection

-protect humans from most infectious diseases
-natural host resistance
-infection site and tissue specificity

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-protect humans from most infectious disease

-exists at birth and always present
-natural host resistance (no memory)
-can be specific for tissue
-chemical and physical barriers, special immune system cells, physiological processes and molecular defences

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natural host resistance

susceptibility to pathogens varies from species to species
-ex anthrax: fatal blood infection in cattles vs cutaneous in humans

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infection site and tissue specificity

-pathogens prefer a specific body site to initiate infection
-nutritional and metabolic needs
-eg. colstridium tetani: ingested vs deep wounds

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physical and chemical barriers

mucous membranes
skin
respiratory tract
gastrointestinal tract
genitourinary tract

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genitourinary tract

-urine-metabolic waste products, toxic to many microbes
-flushing action-mechanical removal of mircboes
-normal microbiota
-ex. vaginal epithelial cells produce glycogen
-lactobacillus acidophilus ferments the ferments the flucose to lactice acid
-pH~3-5

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gastrointestinal tract

stomach
small intestine
large intsetine

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stomach

-strong acidity (pH~2)
-proteolytic enzymes
-destroys most microbes

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small intestine

-rapid change in pH
-pancreatic enzymes
-bile
-destroy microbes

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large intestine

the normal microbiota
-microbes that already reside in and on the human body
-take up attachement sites
-limit available nutrients
-make antimicrobial compounds

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respiratory tract

-the mucocilliary escalator
*ciliated cells line the mucous membranes of the airways
*sweeping action moves mucous and microbes away from the lungs

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mucous membranes

-mucous traps microbes
-contains antimicrobial secretions
ex.
-lysozyme-cuts B-1,4 glycosidic bonds in peptidoglycan
-defensins-antimicrobial peptides that poke holes in bacterial cell membranes

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skin

-prevents invasion by microbes
-protective protein-keratin
-slightly acidic ~pH 5
-high [NaCl]- periodic drying

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the lymphatic system

a collection of tissues that bring specialized cells (lymphocytes) into contact with foreign material (antigens)

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lymphatic system is made up of

lymphoid organs and lymph vessels that carry fluid (lymph)
-similar to blood containing white blood cells (leukocytes)
-but without red blood cells

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lymphoid organs

-primary lymphoid organs
-secondary lymphoid organs
-mucosa associated lymphoid tissue (MALT)

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primary lymphoid organs

bone marrow and thymus- leukocytes are produces and mature

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secondary associated lymphoid organs

-lymph nodes, spleen, MALT
-contains leukocytes arranged to filter out microbes and antigens

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MALT

leukocytes constantly sample their surroundings by phagocytosis looking for foreign material

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leukocytes (white blood cells)

-cells that circulate in the blood and lymph, and reside in lymphoid organs
-involved in both branches of the immune response (innate and adaptive)

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three types of leukocytes

1. granulocytes
2. monocytes
3. lymphocytes

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granulocytes

-cytoplasm contains granules filled with reactive chemicals
-can kill microbes
-signal other components of immunity
3 types:
basophils and mast cells
eosinophils
neutrophils

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monocytes

-circulate in the blood and then migrate into tissues and differentiate into macrophages and dendritic cells
-strongly phagocytic cells involved in antigen presentation
2 types:
macrophages
dendritic cells

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lymphocytes

-specialized leukocytes involved primarily in the adaptive immune response
-circulate through the blood and reside in lymphoid organs
3 types :
1. B lymphocytes (B cells)
2. T lymphocytes (T cells)
3. Natural Killer cells (NK cells)

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basophils and mast cells

-granules stain with basic dyes
-non phagocytic
-circulate in blood (basophils) or reside in mucosal tissue (mast cells)
-can be triggered to degranulate
-release vasoactive mediators
*trigger inflammation
ex. histamine-involved in the allergic response

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eosinophils

-granules stain with acidic dyes
-non phagocytic
-can leave the blood and enter tissues in areas of inflammation
-attck large parasites: protozoa and parasitic worms
-release reactive oxygen intermediates:
-O2-, H2O2, OH*
-destroy parasite from the outside

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Neutrophils

-granules are filled with digestive enzymes: lysozyme and defensins
-circulate in blood and migrate to infection sites
-highly phagocytic-"eat" invading bacteria
-central component of innate immunity

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macrophages

-reside in tissues- lungs, liver, spleen. connective tissues
-specific surface molecules recognize pathogens-Toll-like receptors:
-LPS, peptidoglycan, fungal cell walls etc.
-induces phagocytosis

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dendritic cells

-reside in tissues that serve as common entry points for pathogens
-skin- "langerhan's cells"
-mucous membranes of the nose, lungs and intestines
-constantly sample surroundings by phagocytosis
-migrate to lymphoid organs
-they then present foreign antigens on their surface to B ant T lymphocytes - trigger the specific (adaptive) immune response

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B lymphocytes

b cells
- antibody producing cells
-involved in the humoral immune response

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T lymphocytes

T cells
-involved in the cell mediated immune response

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natural killer cells (NK cells)

-destroy abnormal body cells:
cancer cells
celles infected by bacteria or viruses

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leukocytes: recap
granulocytes

basophils/ mast cells
eosinophils
neutrophils

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leukocytes: recap
agranulocytes

monocytes
macrophages
dendritic cells
lymphocytes (Band T lymphocytes, NK cells)

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innate immunity

-the innate ability to destroy a pathogen that has never been encountered before

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innate immunity involves phagocytic leukocytes (neutrophils and macrophages) that recognize...

pathogen-associated molecular patterns (PAMPs)
*lipopolysaccharide
*lipoteichoic acid
*flagellin

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phagocytes have ...

toll-like receptors (pattern recognition receptors or PRRs)
*interacts with a PAMP
*triggers phagocytosis
*binding by phagocyte PRR activates phagocytosis to kill pathogen

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innate response mechanism: phagocytosis

-Phagocytes engulf and destroy invading microbes
-engulfs it into a phagosome
-fuses with a lysosome to form a phgolysosome

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phagosomes are filled with

-lysozyme and defensins
-proteases
-lipases
-nuclease
-oxygen independent killing

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proteases

degrade proteins

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lipases

degrade phospholipids

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nuclease

degrade nucleic acids

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oxygen independent killing

-activated phagocytes produce reactive oxygen compounds:
*H2O2, O2-, OH,HOCI,NO
*kill ingested microbes by oxidizing cell components

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once invaders have been killed by phagocytosis

-neutrophils perform exocytosis
-fragments are expelled from the cell
-macrophages and dendritic cells become antigen presenting cells
-fragments of the cell surface to trigger an adaptive immune response

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inflammation

-general, non-specific reaction to pathogens, toxins or tissue damage

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five cardinal signs of inflammation

redness
warmth
pain
swelling
loss of function

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pro-inflammatory cytokines

in response to infection, injured tissue and leukocytes release pro-inflammatory cytokines
-blood vessels dilate
-brings more leukocytes to the area
-vessel walls become permeable
-leukocytes can squeeze into tissues -extravasation
-attack invading pathogens
-temperature increase may slow the growth of pathogens
-blood leaking into tissue spaces can clot
-prevents movement of pathogens